another emc resource from emc standards...helping you solve your emc problems 9 bracken view,...

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Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:[email protected] Another EMC resource from EMC Standards Complying with IEC/EN 61800-3 Good EMC Engineering Practices in the Installation of Power Drive Syst

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Page 1: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

Helping you solve your EMC problems

9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:[email protected]

Another EMC resourcefrom EMC Standards

Complying with IEC/EN 61800-3 Good EMCEngineering Practices in the Installation of PowerDrive Syst

Page 2: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

Com

plyi

ng w

ith IE

C/E

N 6

1800

-3G

ood

EMC

Eng

inee

ring

Prac

tices

in th

eIn

stal

latio

n of

Pow

er D

rive

Syst

ems

REO

UK

LTD

Page 3: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

RE

O (U

K) L

TD, U

nits

2 -

4 C

allo

w H

ill R

oad,

Cra

ven

Arm

s B

usin

ess

Par

k, C

rave

n A

rms

Shr

opsh

ire S

Y7

8NT

Tel:

0158

8 67

3411

Fax

: 015

88 6

7271

8E

mai

l: sa

les@

reo.

co.u

k W

ebsi

te: w

ww

.reo.

co.u

k

Page 4: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

11

Con

tent

s1.

Intro

duct

ion

22.

Wha

t is

not c

over

ed in

this

Gui

de7

3. C

ost i

mpl

icat

ions

94.

Em

issi

ons

175.

Imm

unity

546.

EM

C s

uppr

essi

on p

rodu

cts

from

RE

O56

7. R

efer

ence

s an

d fu

rther

read

ing

57

Com

plyi

ng w

ith IE

C/E

N 6

1800

-3—

Goo

d EM

C E

ngin

eerin

g Pr

actic

es in

the

Inst

alla

tion

of P

ower

Driv

e Sy

stem

s—

Kei

th A

rmst

rong

Che

rry

Clo

ugh

Con

sulta

nts,

ww

w.c

herr

yclo

ugh.

com

Fron

t and

bac

k co

ver p

ictu

res

© J

orge

n U

dvan

g - i

stoc

kpho

to.c

om

Page 5: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

23

IEC

924

/04

Cop

ied

from

Fig

ure

2 of

EN

/IEC

618

00-3

:200

4Fi

gure

2:

Defi

niti

ons

of P

DS,

CD

M a

nd B

DM

, sho

win

g th

e PD

S’s

“por

ts”

1. In

trod

uctio

nTh

is G

uide

is fo

r wha

t EN

/IEC

618

00-

3 [1

] cal

ls “P

ower

Driv

e S

yste

ms”

(P

DS

s), w

hich

are

AC

or D

C m

otor

sp

eed

cont

rol u

nits

mor

e us

ually

ca

lled

varia

ble

spee

d dr

ives

(VS

Ds)

or

adj

usta

ble

spee

d dr

ives

(AS

Ds)

. V

SD

s fo

r AC

mot

ors

only

are

ofte

n ca

lled

varia

ble

frequ

ency

driv

es

(VFD

s), a

djus

tabl

e fre

quen

cy d

rives

(A

FDs)

, or j

ust i

nver

ter d

rives

.

EN

618

00-3

is li

sted

und

er th

e E

MC

D

irect

ive

[2],

and

so m

ay b

e us

ed fo

r de

clar

ing

PD

Ss

in c

onfo

rmity

with

it.

At t

he ti

me

of w

ritin

g, th

e E

MC

D

irect

ive

has

been

app

lyin

g its

200

4 ve

rsio

n [1

] sin

ce th

e 1s

t Oct

ober

20

07, w

hich

mea

ns th

at a

ll P

DS

s su

pplie

d in

the

EU

sin

ce th

en s

houl

d lis

t EN

618

00-3

:200

4 on

thei

r EU

D

ecla

ratio

ns o

f Con

form

ity, a

nd

prov

ide

the

appr

opria

te te

st e

vide

nce

in th

eir “

Tech

nica

l Doc

umen

tatio

n Fi

le”

– if

they

are

follo

win

g th

e “s

tand

ards

ro

ute

to c

onfo

rmity

” (se

e [3

]).

EN

618

00-3

:200

4 is

iden

tical

to IE

C

6180

0-3:

2004

, so

this

Gui

de is

equ

ally

ap

plic

able

out

side

of t

he E

urop

ean

Uni

on (E

U) w

here

the

IEC

ver

sion

or s

ome

natio

nal s

tand

ard

base

d up

on it

– is

app

lied.

Eve

n w

here

ther

e ar

e no

lega

l EM

C

requ

irem

ents

, com

plyi

ng w

ith E

N/IE

C

6180

0-3

is g

ood

engi

neer

ing

prac

tice

that

will

hel

p im

prov

e pr

ofi ts

ove

rall,

ov

er th

e m

ediu

m a

nd lo

ng te

rm,

Inst

alla

tion

or p

art o

f ins

talla

tion

Pow

er D

rive

Sys

tem

s (P

DS

)

CD

M (C

ompl

ete

Driv

e M

odul

e)

Mot

or a

nd S

enso

rs

Driv

en e

quip

men

t

Sys

tem

con

trol

and

sequ

enci

ngB

DM

(Bas

ic D

rive

Mod

ule)

Con

trol

conv

erte

ran

d pr

otec

tion

Feed

ing

sect

ion

Fiel

d su

pply

dyna

mic

bra

king

Aux

illia

ries,

oth

ers

.....

IEC

923

/04

e.g.

a s

yste

m w

ithin

an in

stal

latio

n

Cop

ied

from

Fig

ure

1of

EN

/IEC

618

00-3

:200

4

Figu

re 1

: D

efi n

ition

s of

PD

S, C

DM

and

BD

M

and

will

als

o he

lp in

crea

se c

usto

mer

co

nfi d

ence

and

mar

ket s

hare

.

1.1.

The

defi

niti

on o

f a P

DS

Acc

ordi

ng to

EN

/IEC

618

00-3

[1],

a P

DS

is a

n ad

just

able

spe

ed A

C o

r D

C m

otor

driv

e, c

onsi

stin

g of

a b

asic

dr

ive

mod

ule

(BD

M),

whi

ch is

par

t of

the

com

plet

e dr

ive

mod

ule

(CD

M),

whi

ch –

whe

n co

nnec

ted

to it

s m

otor

beco

mes

a P

DS

, whi

ch in

turn

is

part

of a

sys

tem

or i

nsta

llatio

n, a

s sh

own

in F

igur

e 1.

IEC

618

00-1

, IE

C 6

1800

-2 a

nd IE

C

6180

0-4

prov

ide

the

deta

ils fo

r the

de

fi niti

ons

used

in F

igur

es 1

and

2.

If th

e P

DS

has

its

own

dedi

cate

d tra

nsfo

rmer

, thi

s tra

nsfo

rmer

is

incl

uded

as

a pa

rt of

its

CD

M.

A no

n-ex

haus

tive

list o

f PD

S

appl

icat

ions

incl

udes

:

Mac

hine

tool

s, ro

bots

, tes

t eq

uipm

ent i

n pr

oduc

tion,

test

be

nche

s;P

aper

mac

hine

s, te

xtile

pro

duct

ion

mac

hine

, cal

ende

rs in

the

rubb

er

indu

stry

;P

roce

ss li

nes

in p

last

ic in

dust

ries

or in

met

al in

dust

ries,

rolli

ng m

ills;

Cem

ent c

rush

ing

mac

hine

s,

cem

ent k

ilns,

mix

ers,

cen

trifu

ges,

ex

trusi

on m

achi

nes;

Dril

ling

mac

hine

s;C

onve

yors

, mat

eria

l han

dlin

g m

achi

nes,

hoi

stin

g eq

uipm

ent

(cra

nes,

gan

tries

, etc

.);

Pro

puls

ion

of s

hips

, etc

. (bu

t not

tra

ctio

n dr

ives

or e

lect

ric v

ehic

les)

;P

umps

, fan

s, e

tc.

The

PD

Ss

may

be

conn

ecte

d to

ei

ther

indu

stria

l or p

ublic

mai

ns p

ower

di

strib

utio

n ne

twor

ks. A

n “in

dust

rial

netw

ork”

is c

onsi

dere

d to

be

one

that

is s

uppl

ied

by a

ded

icat

ed h

igh

volta

ge (H

V) d

istri

butio

n tra

nsfo

rmer

, or

its

own

gene

rato

r, w

hich

sup

plie

s on

ly in

dust

rial c

usto

mer

s or

, for

ex

ampl

e a

ship

or o

ffsho

re d

rillin

g rig

.

A pu

blic

pow

er d

istri

butio

n ne

twor

k is

on

e th

at o

pera

tes

at lo

w v

olta

ges

(e.g

. 11

5/23

0/40

0V) a

nd s

uppl

ies

dom

estic

pr

emis

es. T

hese

net

wor

ks u

sual

ly

have

an

earth

ed (g

roun

ded)

neu

tral.

Whe

re a

n in

dust

rial s

ite is

pow

ered

fro

m a

low

vol

tage

mai

ns p

ower

di

strib

utio

n, a

s so

met

imes

hap

pens

, th

e m

ains

dis

tribu

tion

netw

ork

on th

at

site

is tr

eate

d as

a p

ublic

net

wor

k.

As

Figu

re 1

sho

ws,

a P

DS

may

driv

e so

me

equi

pmen

t (e.

g. a

win

ch, p

ump,

Figu

re 2

sho

ws

anot

her v

iew

of a

P

DS

, thi

s tim

e id

entif

ying

the

vario

us

“por

ts” t

hat a

re te

sted

by

[1].

Page 6: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

45

fan,

etc

.), a

nd/o

r be

part

of a

sys

tem

, an

d/or

be

part

of a

n in

stal

latio

n, b

ut

only

the

PD

S is

cov

ered

by

EN

/IEC

61

800-

3 (s

ee 1

.3).

1.2.

Th

e re

quire

men

ts o

f EN

/IEC

618

00-3

[1] i

nclu

des

requ

irem

ents

for P

DS

s w

ith B

DM

inp

ut a

nd/o

r out

put

volta

ges

(line

-to-li

ne) o

f up

to 3

5 kV

A

C rm

s, ra

ted

from

a fe

w h

undr

ed

wat

ts to

hun

dred

s of

MW

, ins

talle

d in

re

side

ntia

l, co

mm

erci

al o

r ind

ustri

al

loca

tions

.

It cl

aim

s to

ach

ieve

EM

C fo

r suc

h ap

plic

atio

ns (b

ut s

ee 1

.3) b

ut w

arns

th

at it

can

not c

over

ext

rem

e ca

ses

that

cou

ld o

ccur

(but

whi

ch a

re

assu

med

to h

ave

an e

xtre

mel

y lo

w

prob

abili

ty).

It al

so w

arns

that

it d

oes

not c

over

the

EM

C p

erfo

rman

ce in

the

case

of f

aults

occ

urrin

g, w

hich

is v

ery

rele

vant

for s

ectio

n 2.

4 la

ter i

n th

is

Gui

de.

[1] s

peci

fi es

emis

sion

s lim

its,

imm

unity

leve

ls, a

nd te

st m

etho

ds

for a

PD

S a

ccor

ding

to it

s in

tend

ed

appl

icat

ion

and

the

com

pete

ncy

of

its in

stal

ler.

It do

es th

is b

y de

fi nin

g tw

o di

ffere

nt e

lect

rom

agne

tic

“env

ironm

ents

” or l

ocat

ions

, and

fo

ur d

iffer

ent “

Cat

egor

ies”

of i

nsta

ller

com

pete

ncy,

as

disc

usse

d be

low

.

1.2.

1. T

he F

irst E

nviro

nmen

tTh

is e

nviro

nmen

t inc

lude

s do

mes

tic

prem

ises

, and

est

ablis

hmen

ts d

irect

ly

conn

ecte

d w

ithou

t int

erm

edia

te

trans

form

ers

to a

low

-vol

tage

pow

er

supp

ly n

etw

ork

whi

ch s

uppl

ies

build

ings

use

d fo

r dom

estic

pur

pose

s.

Hou

ses,

apa

rtmen

ts, c

omm

erci

al

prem

ises

or o

ffi ce

s in

a re

side

ntia

l bu

ildin

g ar

e ex

ampl

es o

f Firs

t E

nviro

nmen

t loc

atio

ns.

1.2.

2. T

he S

econ

d En

viro

nmen

tTh

is e

nviro

nmen

t inc

lude

s al

l es

tabl

ishm

ents

oth

er th

an th

ose

dire

ctly

con

nect

ed to

a lo

w v

olta

ge

mai

ns p

ower

sup

ply

netw

ork

whi

ch

supp

lies

build

ings

use

d fo

r dom

estic

pu

rpos

es.

Indu

stria

l are

as, a

nd te

chni

cal a

reas

of

any

bui

ldin

g th

at a

re fe

d fro

m

thei

r ow

n de

dica

ted

trans

form

er a

re

exam

ples

of S

econ

d E

nviro

nmen

t lo

catio

ns.

1.2.

3. C

ateg

ory

C1

This

cat

egor

y is

for P

DS

s w

ith ra

ted

volta

ge le

ss th

an 1

,000

V, in

tend

ed

for u

se in

the

Firs

t Env

ironm

ent,

perm

itted

to b

e in

stal

led

by a

nyon

e.

1.2.

4. C

ateg

ory

C2

This

cat

egor

y is

for P

DS

s w

ith ra

ted

volta

ge le

ss th

an 1

,000

V, w

hich

is

neith

er a

plu

g-in

dev

ice

nor a

mov

able

de

vice

and

, whe

n us

ed in

the

Firs

t

Env

ironm

ent,

is in

tend

ed to

be

inst

alle

d an

d co

mm

issi

oned

onl

y by

a

“pro

fess

iona

l”.

A pr

ofes

sion

al is

defi

ned

as

a pe

rson

or a

n or

gani

satio

n ha

ving

ne

cess

ary

skill

s in

inst

allin

g an

d/or

co

mm

issi

onin

g P

DS

s, in

clud

ing

thei

r E

MC

asp

ects

.

1.2.

5. C

ateg

ory

C3

This

app

lies

to P

DS

s of

rate

d vo

ltage

le

ss th

an 1

,000

V, i

nten

ded

for u

se

in th

e S

econ

d E

nviro

nmen

t and

no

t int

ende

d fo

r use

in th

e Fi

rst

Env

ironm

ent,

perm

itted

to b

e in

stal

led

by a

nyon

e.

1.2.

6. C

ateg

ory

C4

This

app

lies

to P

DS

s of

rate

d vo

ltage

eq

ual t

o or

abo

ve 1

,000

V, o

r rat

ed

curr

ent e

qual

to o

r abo

ve 4

00A

, or

inte

nded

for u

se in

com

plex

sys

tem

s in

the

Sec

ond

Env

ironm

ent,

perm

itted

to

be

inst

alle

d by

any

one.

1.3.

Em

issi

ons

and

imm

unity

of

PD

Ss a

s pa

rt o

f sys

tem

s or

in

stal

latio

nsA

s m

entio

ned

abov

e, a

PD

S m

ay

be a

par

t of a

sys

tem

, or p

art o

f an

inst

alla

tion,

but

EN

/IEC

618

00-3

[1]

only

cov

ers

the

PD

S it

self.

How

ever

, for

com

plia

nce

with

th

e E

MC

Dire

ctiv

e, c

usto

mer

sp

ecifi

catio

ns, o

r jus

t goo

d E

MC

engi

neer

ing

prac

tices

, the

ent

ire

syst

em o

r par

t of a

n in

stal

latio

n m

ay

be c

over

ed b

y ot

her E

MC

sta

ndar

ds

– m

ost l

ikel

y th

e ge

neric

sta

ndar

ds:

EN

/IEC

610

00-6

-1, i

mm

unity

re

quire

men

ts fo

r res

iden

tial,

com

mer

cial

and

ligh

t ind

ustri

al

envi

ronm

ents

EN

/IEC

610

00-6

-2, i

mm

unity

re

quire

men

ts fo

r the

indu

stria

l en

viro

nmen

tE

N/IE

C 6

1000

-6-3

, em

issi

ons

requ

irem

ents

for r

esid

entia

l, co

mm

erci

al a

nd li

ght i

ndus

trial

en

viro

nmen

tsE

N/IE

C 6

1000

-6-4

, em

issi

ons

requ

irem

ents

for t

he in

dust

rial

envi

ronm

ent

In th

is c

ase,

it is

pos

sibl

e fo

r a P

DS

th

at is

com

plia

nt w

ith [1

] to

caus

e th

e sy

stem

or i

nsta

llatio

n th

at it

is

part

of to

fail

to c

ompl

y w

ith th

e E

MC

st

anda

rds

that

app

ly to

it. T

here

are

tw

o re

ason

s w

hy th

is c

ould

occ

ur:

a) T

he e

mis

sion

s pe

rmitt

ed b

y [1

] for

th

e P

DS

mig

ht e

xcee

d th

e em

issi

ons

limits

per

mitt

ed b

y ot

her s

tand

ards

for

the

syst

em o

r ins

talla

tion

cont

aini

ng

the

PD

S. F

or e

xam

ple,

som

e lim

its

that

are

per

mitt

ed b

y [1

] for

som

e P

DS

Cat

egor

ies

exce

ed th

e lim

its

perm

itted

by

the

appr

opria

te g

ener

ic

stan

dard

for t

he s

ame

type

of

envi

ronm

ent b

y m

ore

than

20d

B.

b) T

here

may

be

seve

ral P

DS

s in

one

sy

stem

(e.g

. the

sau

sage

mac

hine

in

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67

2. W

hat i

s no

t cov

ered

in th

is G

uide

2.1.

Tes

ting

toEN

/IEC

618

00-3

This

Gui

de is

onl

y co

ncer

ned

with

th

e us

e of

goo

d E

MC

eng

inee

ring

inst

alla

tion

prac

tices

to h

elp

PD

Ss

com

ply

with

EN

/IEC

618

00-3

[1],

it do

es n

ot c

over

the

actu

al te

stin

g te

chni

ques

that

are

use

d by

[1].

RE

O h

ave

seve

ntee

n G

uide

s [4

] tha

t de

tail

how

to a

ctua

lly p

erfo

rm th

e va

rious

test

s re

quire

d by

[1],

incl

udin

g th

e si

tuat

ion

whe

re th

e te

st c

anno

t be

car

ried

out a

t a “c

ontro

lled

EM

C

site

”, su

ch a

s in

side

a te

st la

bora

tory

’s

anec

hoic

cha

mbe

r.

[1] a

lso

incl

udes

gui

danc

e on

wha

t to

do

whe

n te

stin

g ha

s to

be

done

on

-site

, or w

hen

the

mai

ns c

urre

nt

requ

ired

by a

PD

S e

xcee

ds 1

00A

. If

furth

er g

uida

nce

is re

quire

d on

on-

site

te

stin

g, [5

] may

pro

ve u

sefu

l.

2.2.

Com

plyi

ng w

ith th

e EM

C

Dire

ctiv

eIt

is n

ot th

e ai

m o

f thi

s G

uide

to

disc

uss

how

a m

anuf

actu

rer s

houl

d go

ab

out l

egal

ly c

ompl

ying

with

the

EM

C

Dire

ctiv

e [2

] [6]

, as

impl

emen

ted

in th

e va

rious

nat

iona

l law

s of

the

Eur

opea

n U

nion

’s (E

U’s

) Mem

ber S

tate

s, s

uch

as [7

] [8]

for t

he U

nite

d K

ingd

om (U

K).

The

com

plia

nce

met

hods

that

are

av

aila

ble

are

disc

usse

d in

[3].

2.3.

Hum

an H

ealth

and

Sa

fety

The

very

hig

h vo

ltage

s an

d cu

rren

ts

asso

ciat

ed w

ith h

igh-

pow

er P

DS

s ca

n ca

use

a va

riety

of p

robl

ems

for

heal

th a

nd s

afet

y. E

N 6

1800

-5-1

[l]

cove

rs e

lect

rical

, the

rmal

and

ene

rgy

haza

rds

of P

DS

s, b

ut d

oes

not c

over

hu

man

hea

lth e

ffect

s du

e to

exp

osur

e to

ele

ctric

and

/or m

agne

tic fi

elds

(E

MFs

).

All

PD

Ss

that

dec

lare

com

plia

nce

with

th

e Lo

w V

olta

ge D

irect

ive

[9] m

ust

also

now

dec

lare

com

plia

nce

with

the

EM

F R

egul

atio

ns [1

0]. W

hile

ther

e ar

e no

EM

F st

anda

rds

spec

ifi ca

lly fo

r P

DS

s, it

will

pro

babl

y be

bes

t to

appl

y th

e “g

ener

ic E

MF

stan

dard

” EN

623

11

[11]

.

A w

orkp

lace

Hea

lth a

nd S

afet

y D

irect

ive

on E

MF

also

exi

sts

[12]

, bu

t at t

he ti

me

of w

ritin

g is

not

fully

in

forc

e. L

ike

all H

ealth

and

Saf

ety

dire

ctiv

es, i

t app

lies

to th

e ow

ners

/us

ers

of a

site

or t

he e

quip

men

t on

it,

and

not t

o m

anuf

actu

rers

who

sup

ply

them

with

equ

ipm

ent.

Nei

ther

of t

hese

issu

es a

re d

iscu

ssed

fu

rther

in th

is G

uide

.

Figu

re 3

), an

d si

nce

thei

r em

issi

ons

will

add

up

they

cou

ld e

xcee

d th

e lim

its fo

r the

ove

rall

syst

em o

r in

stal

latio

n.

It w

as b

ecau

se o

f a) t

hat t

he

Eur

opea

n A

ssoc

iatio

n of

Com

pete

nt

Bod

ies

(EC

AC

B, d

isba

nded

si

nce

2004

/108

/EC

, has

repl

aced

C

ompe

tent

Bod

ies

with

Not

ifi ed

Bod

ies

and

chan

ged

the

com

plia

nce

met

hods

, see

[3])

com

plai

ned

to th

e E

urop

ean

Com

mis

sion

(EC

) abo

ut

the

listin

g of

EN

618

00-3

und

er th

e E

MC

Dire

ctiv

e, a

nd a

sked

that

it b

e re

mov

ed fr

om th

at li

st. I

t was

not

re

mov

ed, b

ut s

hortl

y af

terw

ards

the

EC

em

ploy

ed a

n E

MC

Con

sulta

nt w

ith

the

aim

of e

nsur

ing

they

did

not

mak

e su

ch e

mba

rras

sing

mis

take

s ag

ain.

Figu

re 3

: Exa

mpl

e of

a m

achi

ne w

ith a

num

ber o

f PD

SsPa

rt o

f a c

ompl

ex in

stal

latio

n....

The

cont

rol c

ubic

le fo

r the

sau

sage

mac

hine

inst

alle

d at

Sto

rk T

owns

end

B.V

., Th

e N

ethe

rland

s, in

200

6. 1

0 m

etre

s lo

ng; 6

0 va

riabl

e sp

eed

driv

es 1

8 m

ulti-

axis

ser

vo d

rives

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89

3. C

ost i

mpl

icat

ions

3.1.

The

EM

C o

f PD

Ss,

fi nan

cial

risk

s, a

nd th

e pe

rils

of s

hort

-term

ism

It is

qui

te p

ract

ical

to d

esig

n a

BD

M

(see

2.6

) so

that

any

PD

S u

sing

it is

gu

aran

teed

to c

ompl

y w

ith E

N/IE

C

6180

0-3

(and

the

EM

C D

irect

ive)

re

gard

less

of h

ow it

is in

stal

led

and

how

the

PD

S th

at e

mpl

oys

it is

co

nfi g

ured

. How

ever

, suc

h B

DM

s w

ill

alm

ost c

erta

inly

cos

t mor

e.

Whe

n us

ing

such

a B

DM

, a

man

ufac

ture

r who

inte

grat

es it

into

a

PD

S th

at h

e se

lls to

an

end-

user

(o

r the

ir m

ain

cont

ract

or) w

ill b

e ab

le

to d

emon

stra

te c

ompl

ianc

e w

ith th

e E

MC

Dire

ctiv

e [2

] [7]

with

out h

avin

g to

test

to E

N/IE

C 6

1800

-3. A

ll th

ey

will

nee

d to

do

is to

incl

ude

a fe

w

verifi

ed

EM

C d

ocum

ents

from

the

BD

M m

anuf

actu

rer,

in th

eir T

echn

ical

D

ocum

enta

tion

File

[3].

Suc

h P

DS

s w

ill b

e la

rgel

y un

affe

cted

by

EM

I in

thei

r ope

ratio

nal

envi

ronm

ent,

and

so w

ill g

ener

ally

op

erat

e w

ith g

reat

er p

reci

sion

. Whe

n us

ed in

man

ufac

turin

g pr

oces

ses

they

of

ten

impr

ove

yiel

ds a

nd q

ualit

y, a

nd

they

ofte

n pr

ove

to b

e m

ore

relia

ble.

A

ll th

is w

ill re

duce

thei

r ove

rall

cost

-of

-ow

ners

hip

for t

heir

user

s, a

nd a

lso

gene

rally

redu

ce th

e w

arra

nty

cost

s fo

r the

ir m

anuf

actu

rers

, som

etim

es

very

sig

nifi c

antly

.

Suc

h go

od E

MC

des

ign

incr

ease

s th

e bi

ll-of

-mat

eria

ls (B

OM

) cos

t of t

he

BD

M, a

nd m

ost m

anuf

actu

rers

wou

ld

assu

me

that

they

mus

t the

refo

re s

ell

it fo

r a h

ighe

r pric

e. B

ut th

is is

not

ne

cess

arily

the

case

, bec

ause

(for

ex

ampl

e) th

eir p

rodu

ct c

ould

hav

e lo

wer

war

rant

y co

sts,

and

/or m

ight

win

a

muc

h la

rger

mar

ket s

hare

bec

ause

of

its

ease

of u

se [2

3]. S

o th

ey m

ight

m

ake

as m

uch

or m

ore

profi

t ev

en

whe

n se

lling

it fo

r the

sam

e pr

ice

as

a m

ore

typi

cal B

DM

that

doe

s no

t co

ntro

l EM

C s

o w

ell a

nd s

o re

quire

s an

y P

DS

it is

use

d in

to g

o th

roug

h co

stly

test

s to

EN

/IEC

618

00-3

, to

be a

ble

to s

how

due

dili

genc

e in

co

mpl

ying

with

the

EM

C D

irect

ive.

This

all

soun

ds g

ood,

but

it ra

rely

ha

ppen

s in

real

life

bec

ause

of s

hort-

term

ism

– m

anag

ers

usua

lly o

nly

look

ah

ead

as fa

r as

the

next

qua

rter’s

fi n

anci

al fi

gure

s –

so e

ven

very

si

gnifi

cant

pos

sibi

litie

s fo

r med

ium

and

lo

ng-te

rm fi

nanc

ial g

ains

, im

prov

ing

profi

tabi

lity

and

retu

rn-o

n-in

vest

men

t (R

OI)

are

igno

red.

Som

etim

es th

e be

nefi t

s of

inve

stin

g in

goo

d E

MC

en

gine

erin

g ar

e di

scou

nted

bec

ause

of

a la

ck o

f app

reci

atio

n of

EM

C

issu

es.

Sho

rt-te

rmis

m m

eans

that

buy

ers

are

look

ing

for t

he c

heap

est B

DM

, and

of

ten

deci

de s

olel

y on

the

basi

s of

cr

ude

“kW

ver

sus

£” c

ompa

rison

s.

For t

his

reas

on, a

nd o

ther

s, m

ost

BD

M m

anuf

actu

rers

’ sal

esm

en fe

el

2.4.

Fun

ctio

nal S

afet

yIt

is a

lso

not t

he a

im o

f thi

s G

uide

to

dis

cuss

the

Func

tiona

l Saf

ety

issu

es o

f PD

Ss,

oth

er th

an to

sa

y th

at s

ince

ele

ctro

mag

netic

in

terfe

renc

e (E

MI)

can

caus

e P

DS

s to

suf

fer e

rror

s or

mal

func

tions

(e.g

. un

com

man

ded

chan

ges

in s

peed

, to

rque

, dire

ctio

n, e

tc.)

– w

here

thes

e co

uld

have

con

sequ

ence

s fo

r saf

ety

risks

, com

plyi

ng w

ith E

N 6

1800

-3

or a

ny o

ther

EM

C te

st s

tand

ards

, ev

en m

ilita

ry o

r aer

ospa

ce o

nes,

is

insu

ffi ci

ent f

or e

stab

lishi

ng a

def

ence

of

due

dili

genc

e.

EN

618

00-5

-2 [1

3] a

pplie

s th

e ba

sic

stan

dard

on

Func

tiona

l Saf

ety

EN

61

508

[14]

to P

DS

s, b

ut –

like

[14]

does

not

pre

scrib

e w

hat t

o do

abo

ut

the

poss

ibili

ty o

f EM

I. E

MI c

an c

ause

a

varie

ty o

f pro

blem

s fo

r mot

or d

rives

, w

hich

mig

ht b

e co

stly

(e.g

. dow

ntim

e)

or h

ave

safe

ty ri

sks,

as

show

n by

so

me

of th

e re

al-li

fe a

necd

otes

in [1

5].

To c

over

EM

I it i

s ne

cess

ary

to

appl

y th

e ba

sic

stan

dard

on

EM

C

for F

unct

iona

l Saf

ety

[16]

, for

whi

ch

the

IET

have

pro

duce

d a

help

ful

and

prac

tical

9-s

tep

man

agem

ent

proc

edur

e [1

7]. E

MC

test

s ha

ve a

role

to

pla

y in

due

dili

genc

e fo

r saf

ety,

but

th

ey c

anno

t be

suffi

cien

t on

thei

r ow

n.

2.5.

Mac

hine

ry S

afet

yA

PD

S a

s de

fi ned

by

the

EN

618

00

serie

s of

sta

ndar

ds is

not

a m

achi

ne

as d

efi n

ed b

y th

e M

achi

nery

Saf

ety

Dire

ctiv

e [1

8], a

nd s

o th

is d

irect

ive

does

not

app

ly to

PD

Ss.

Of c

ours

e, s

yste

m in

tegr

ator

s an

d ow

ners

of fi

xed

inst

alla

tions

(usi

ng th

e de

fi niti

on in

[2] a

nd [7

]) w

ill o

ften

use

a P

DS

to p

rovi

de th

e m

otiv

e po

wer

fo

r a m

achi

ne th

at d

oes

com

e un

der

the

Mac

hine

ry D

irect

ive,

or o

ne o

f the

H

ealth

and

Saf

ety

at W

ork

Dire

ctiv

es,

in w

hich

cas

e it

is im

porta

nt th

at th

ey

unde

rsta

nd th

e po

ints

mad

e in

2.3

and

2.

4. T

hey

will

fi nd

hel

pful

info

rmat

ion

on E

MC

in [1

9] [2

0] a

nd [1

7].

2.6.

Ele

ctro

nic

and

mec

hani

cal d

esig

n of

bas

ic

driv

e m

odul

es (B

DM

s)Th

is G

uide

doe

s no

t cov

er th

e el

ectro

nic

and

mec

hani

cal d

esig

n an

d as

sem

bly

of th

e B

DM

sec

tion

of P

DS

s, o

r its

cab

inet

or o

ther

en

clos

ure.

But

wel

l-pro

ven

tech

niqu

es

do e

xist

for t

hese

EM

C a

spec

ts o

f B

DM

s, s

ee [2

1] [2

2] a

nd [2

0].

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1011

reck

on th

at a

s m

any

as o

ne-th

ird o

f all

PC

sof

twar

e “c

rash

es” a

re c

ause

d by

E

MI.

We

have

all

expe

rienc

ed th

ese

reco

vera

ble

cras

hes

on o

ur P

Cs

but

how

man

y of

us

have

iden

tifi e

d th

e cr

ash

as a

n E

MI i

ncid

ent a

nd b

roug

ht

it to

the

atte

ntio

n of

the

peop

le w

ho

sit o

n th

e IE

C c

omm

ittee

for c

ompu

ter

EM

C s

tand

ards

?

Ano

ther

issu

e is

that

ther

e is

a ra

pid

incr

ease

in e

lect

roni

c in

stru

men

tatio

n,

cont

rol a

nd c

omm

unic

atio

ns in

all

area

s of

hum

an a

ctiv

ity, i

nclu

ding

sa

fety

-rel

ated

sys

tem

s, a

ll br

ough

t ab

out b

y th

e co

ntin

ual r

educ

tion

in th

e co

sts

of s

emic

ondu

ctor

s (tr

ansi

stor

s).

Als

o, th

e re

duct

ion

in c

osts

of

sem

icon

duct

ors

is b

roug

ht a

bout

by

mak

ing

them

phy

sica

lly s

mal

ler a

nd

oper

atin

g th

em o

n lo

wer

vol

tage

s.

A st

ate-

of-th

e-ar

t mic

ropr

oces

sor

(a “s

ilico

n ch

ip” o

n a

prin

ted

circ

uit b

oard

) at t

he e

nd o

f 200

8 co

uld

cont

ain

as m

any

as 1

bill

ion

sem

icon

duct

ors

and

oper

ate

from

0.

9V D

C p

ower

. It i

s un

fortu

nate

bu

t una

void

able

that

thes

e tre

nds

inev

itabl

y m

ake

them

mor

e su

scep

tible

to E

MI.

This

rapi

d in

crea

se in

ele

ctro

nic

com

plex

ity, p

lus

the

wor

seni

ng o

f el

ectro

nic

imm

unity

, mig

ht re

veal

that

P

DS

s pr

evio

usly

thou

ght t

o be

EM

C

com

plia

nt (b

ecau

se o

f no

com

plai

nts)

w

ere

not s

o, in

fact

. It w

ould

be

a gr

eat p

ity if

the

fi rst

tim

e th

is w

as

disc

over

ed w

as a

n in

cide

nt th

at

invo

lved

a s

erio

us in

jury

or d

eath

(see

2.

4).

In a

ny a

rea

whe

re e

lect

roni

c te

chno

logi

es a

re u

sed,

the

past

is n

ot

a re

liabl

e gu

ide

to th

e fu

ture

.

The

fact

that

ther

e is

no

evid

ence

of

a p

robl

em s

houl

d ne

ver b

e ta

ken

as p

rovi

ng th

at th

eref

ore

ther

e is

no

pro

blem

. Alth

ough

it s

ound

s at

fi r

st li

ke a

reas

onab

le a

rgum

ent,

it ha

s be

en k

now

n si

nce

the

late

18t

h ce

ntur

y th

at is

not

a lo

gica

l con

clus

ion

to m

ake

(see

[25]

). It

is v

ery

disa

ppoi

ntin

g to

fi nd

suc

h an

obv

ious

er

ror i

n an

IEC

sta

ndar

d.

3.3.

Out

put fi

lter

s an

d in

dust

rial P

DSs

Very

few

PD

Ss

use

outp

ut fi

lters

be

caus

e of

thei

r cos

t, bu

t eve

n if

we

igno

re E

MC

issu

es, w

e ha

ve to

ac

know

ledg

e th

at –

with

out o

utpu

t fi l

ters

– h

igh-

pow

er V

SD

s su

ffer f

rom

hi

gh le

vels

of c

omm

on-m

ode

(CM

) cu

rren

t (se

e 4.

2) fl

owin

g th

roug

h th

eir

bear

ings

, whi

ch c

an s

horte

n th

eir l

ife

by a

s m

uch

as te

nfol

d.

Ano

ther

pro

blem

is th

at w

here

long

m

otor

cab

les

are

used

, the

“Far

aday

E

ffect

” cau

ses

the

mot

or’s

driv

e vo

ltage

s to

rise

sig

nifi c

antly

hig

her

than

thos

e ou

tput

by

the

VS

D, w

hich

ca

n de

grad

e th

e in

sula

tion

mat

eria

ls

in th

e ca

bles

and

mot

or w

indi

ngs,

ag

ain

lead

ing

to e

arly

failu

re a

nd

incr

ease

d do

wnt

ime.

may

be

unw

illin

g or

una

ble

to s

ell

a m

ore

cost

ly p

rodu

ct o

n th

e ba

sis

of lo

wer

ove

rall

cost

-of-o

wne

rshi

p,

espe

cial

ly in

regi

ons

of th

e w

orld

w

here

EM

C re

gula

tions

are

not

m

anda

tory

or s

trict

ly e

nfor

ced.

It i

sn’t

help

ed b

y th

e fa

ct th

at m

ost e

ngin

eers

ha

ve d

iffi c

ulty

in p

rese

ntin

g te

chni

cal

argu

men

ts fo

r im

prov

ed p

rofi t

abili

ty

and

RO

I in

a fi n

anci

al m

anne

r tha

t ca

n be

und

erst

ood

by th

e pe

ople

who

ru

n th

eir c

ompa

nies

. Som

e re

med

ies

for t

his

latte

r pro

blem

will

be

foun

d in

[2

4].

The

inev

itabl

e re

sult

of th

is is

that

, in

gen

eral

, BD

M m

anuf

actu

rers

ai

m to

mak

e th

e ch

eape

st p

rodu

cts

they

pos

sibl

y ca

n, w

hich

incr

ease

s th

e co

st a

nd ti

me

burd

ens

for t

he

syst

em in

tegr

ator

s an

d ow

ners

of

fi xed

inst

alla

tions

(as

defi n

ed in

[2],

see

[3]),

who

use

thei

r pro

duct

s to

co

nstru

ct P

DS

s. T

hese

com

pani

es

have

to u

se d

esig

n an

d in

stal

latio

n te

chni

ques

as

desc

ribed

in th

is G

uide

, an

d pe

rform

cos

tly te

stin

g to

EN

/IEC

61

800-

3 on

eac

h P

DS

they

mak

e (s

omet

imes

test

ing

on-s

ite),

to b

e ab

le

to d

ecla

re c

ompl

ianc

e to

the

EM

C

Dire

ctiv

e. T

his

incr

ease

s th

eir o

vera

ll co

sts

and

so s

igni

fi can

tly in

crea

ses

the

pric

e th

at th

ey h

ave

to c

harg

e to

thei

r cus

tom

ers,

abo

ve w

hat t

hey

wou

ld h

ave

to c

harg

e if

they

cou

ld

buy

BD

Ms

that

had

bee

n de

sign

ed

appr

opria

tely.

3.2.

Mai

ns fi

lters

and

in

dust

rial P

DSs

Acc

ordi

ng to

cla

use

D.1

.2.2

in A

nnex

D

of [

1], t

he c

omm

on p

ract

ice

for

man

y ye

ars

has

been

to in

stal

l PD

Ss

with

out m

ains

fi lte

rs. I

t cla

ims

that

the

gene

ral l

ack

of c

ompl

aint

s ab

out r

adio

in

terfe

renc

e fro

m s

uch

inst

alla

tions

in

dica

tes

that

they

ach

ieve

EM

C –

but

th

is is

a v

ery

risky

ass

umpt

ion

to

mak

e.

Ther

e ar

e m

any

reas

ons

why

peo

ple

mig

ht n

ot c

ompl

ain

abou

t int

erfe

renc

e,

why

they

mig

ht n

ot b

e ab

le to

iden

tify

whe

re it

cam

e fro

m, w

hy e

nfor

cem

ent

auth

oriti

es m

ight

not

hav

e th

e re

sour

ces

or e

xper

tise

to in

vest

igat

e,

or w

hy s

uch

inve

stig

atio

ns w

ere

not

repo

rted

to (o

r rem

embe

red

by) t

he

peop

le w

ho w

rote

[1].

Als

o, th

ere

is

ofte

n an

ele

men

t of (

bad)

luck

in m

any

EM

I inc

iden

ts, w

hich

tend

s to

mak

e th

em h

ard

to re

prod

uce

at w

ill, o

ften

mak

ing

EM

I har

d to

“pro

ve” a

fter a

n in

cide

nt.

I fi n

d th

at m

any

peop

le w

ho c

laim

th

eir s

yste

ms

or in

stal

latio

ns d

on’t

have

EM

I pro

blem

s, a

ctua

lly d

on’t

unde

rsta

nd h

ow to

iden

tify

an E

MI

prob

lem

any

way

(if t

hey

have

eve

n he

ard

of it

). Th

ey m

ay h

ave

suffe

red

(or b

e su

fferin

g) fr

om p

robl

ems

that

ar

e de

crea

sing

yie

lds

or in

crea

sing

do

wnt

ime

– bu

t the

y ne

ver r

ecog

nise

d th

em a

s be

ing

caus

ed b

y E

MI.

For e

xam

ple,

som

e co

mpu

ter e

xper

ts

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1213

EN

/IEC

618

00-3

onl

y sp

ecifi

es

limits

for c

ondu

cted

em

issi

ons

over

th

e fre

quen

cy ra

nge

150k

Hz

to

30M

Hz,

and

the

mac

hini

ng c

entre

m

et th

ese

limits

, but

sin

ce it

s dr

ive’

s sw

itchi

ng fr

eque

ncy

was

2kH

z it

emitt

ed s

igni

fi can

t lev

els

of s

witc

hing

ha

rmon

ic n

oise

into

its

mai

ns s

uppl

y fro

m 2

kHz

at 2

kHz

inte

rval

s al

l the

w

ay u

p to

150

kHz

and

beyo

nd. A

t 15

0kH

z an

d ab

ove

the

mai

ns fi

lter

fi tte

d to

the

PD

S a

ttenu

ated

the

nois

e em

issi

ons

to m

eet t

he s

peci

fi cat

ion,

bu

t it d

id n

ot p

rovi

de s

igni

fi can

t at

tenu

atio

n be

low

150

kHz.

All

mai

ns fi

lters

reso

nate

at s

ome

frequ

ency

(see

3.2

.9 o

f [21

], 8.

1.3.

1 of

[26]

or 5

.10

of [1

9]) a

nd s

o do

all

mai

ns d

istri

butio

n ne

twor

ks, d

ue to

th

e co

mbi

natio

n of

pre

dom

inan

tly

indu

ctiv

e w

iring

with

pre

dom

inan

tly

capa

citiv

e el

ectro

nic

load

s (e

.g.

due

to th

e ca

paci

tors

in th

eir E

MI

fi lte

rs o

f pow

er fa

ctor

cor

rect

ion

bank

s, s

ee C

.1.3

.4 o

f [1]

). N

oise

cu

rren

ts fl

owin

g in

them

will

cau

se

ampl

ifi ed

vol

tage

s at

thes

e re

sona

nt

frequ

enci

es, s

omet

imes

as

muc

h as

te

n tim

es h

ighe

r tha

n w

ould

nor

mal

ly

be e

xpec

ted.

[15]

incl

udes

som

e ex

ampl

es o

f ser

ious

pro

blem

s th

at

occu

rred

bec

ause

noi

se w

as a

mpl

ifi ed

in

mai

ns fi

lters

or m

ains

dis

tribu

tion

netw

orks

.

It ca

n co

me

as a

big

sur

pris

e to

fi n

d th

at a

mai

ns fi

lter i

s gi

ving

ga

in in

stea

d of

atte

nuat

ion,

ofte

n in

con

tradi

ctio

n to

the

supp

liers

at

tenu

atio

n ve

rsus

freq

uenc

y cu

rves

! Th

is is

due

to th

e fa

ct th

at m

ains

fi l

ters

are

not

test

ed in

situ

atio

ns th

at

corr

espo

nd to

real

-life

ope

ratio

n.

How

ever

, in

this

exa

mpl

e, if

the

mai

ns fi

lter w

as re

sona

ting

and

givi

ng

ampl

ifi ca

tion,

it w

as b

elow

150

kHz.

The

solu

tion

was

ver

y si

mpl

e –

the

mac

hini

ng c

entre

man

ufac

ture

r re

plac

ed th

e or

igin

al m

ains

fi lte

r on

thei

r PD

S w

ith o

ne th

at p

rovi

ded

relia

ble

atte

nuat

ion

dow

n to

bel

ow

10kH

z. T

his

fi lte

r was

muc

h th

e sa

me

size

as

the

orig

inal

, but

wei

ghed

a lo

t m

ore

and

was

mor

e co

stly.

It w

as a

lso

less

effi

cien

t, dr

oppe

d a

few

mor

e

Figu

re 5

: A

clos

er v

iew

of t

he

10-3

0kH

z no

ise,

abo

ut 1

5V

peak

-to-p

eak

Pha

se-n

eutra

l noi

se is

app

rox.

15V

p-p

at b

etw

een

10 a

nd 3

0 kH

z(P

hase

-ear

th is

sam

e, b

ut o

nly

4Vp-

p)

So

fi lte

ring

a V

SD

’s m

otor

out

put c

an

be a

n ex

celle

nt fi

nanc

ial i

nves

tmen

t!

For e

xam

ple,

the

maj

ority

of e

lect

rical

su

bmer

sibl

e pu

mps

(ES

Ps)

rate

d up

to

aro

und

900-

1100

kW s

ervi

ng th

e oi

l in

dust

ry o

ffsho

re, w

ould

not

func

tion

unle

ss o

utpu

t fi lt

ers

wer

e in

stal

led.

3.4

An

exam

ple

of th

e fi n

anci

al ri

sks

of in

adeq

uate

EM

C e

ngin

eerin

g[1

5] h

as m

any

exam

ples

of c

ostly

pr

oble

ms

caus

ed b

y E

MI f

rom

, or

to, P

DS

s, in

clud

ing

indu

stria

l one

s,

and

I mus

t say

that

ove

r the

last

20

yea

rs, a

lmos

t all

of m

y w

ork

as

in in

depe

nden

t EM

C c

onsu

ltant

in

solv

ing

EM

I pro

blem

s in

indu

stria

l si

tes

has

been

cau

sed

by tw

o el

ectro

nic

tech

nolo

gies

– v

aria

ble

spee

d m

otor

driv

es (i

.e. P

DS

s) a

nd

pers

onal

wire

less

com

mun

icat

ions

(e

.g. p

rivat

e m

obile

radi

o, W

alki

e-ta

lkie

s, c

ellp

hone

s). H

ere

and

in

3.5

are

just

two

exam

ples

of c

ostly

E

MI c

once

rnin

g P

DS

s, w

hich

do

not

appe

ar in

[15]

. [37

] is

anot

her c

ase

stud

y of

sol

ving

a h

igh-

pow

er V

SD

E

MI p

robl

em th

at h

ad b

een

very

co

stly

for t

he d

rive

user

.

This

fi rs

t exa

mpl

e al

so s

how

s th

at

actu

al c

ompl

ianc

e w

ith th

e te

st li

mits

an

d le

vels

in E

N/IE

C 6

1800

-3 d

oes

not a

utom

atic

ally

ens

ure

com

plia

nce

with

the

EM

C D

irect

ive

[2] [

7], o

r en

sure

low

fi na

ncia

l ris

ks.

It co

ncer

ns a

UK

fact

ory

that

had

a

new

(and

ver

y la

rge

and

cost

ly)

prog

ram

mab

le m

achi

ning

cen

tre

inst

alle

d. T

his

used

a 5

0kW

PD

S

(act

ually

a V

FD) t

hat c

ompl

ied

with

E

N/IE

C 6

1800

-3, s

o w

as a

ssum

ed

to c

ompl

y w

ith th

e E

MC

Dire

ctiv

e [2

] [7

]. B

ut w

hen

it w

as o

pera

ted

it pu

t ab

out 1

5V p

eak-

to-p

eak

at b

etw

een

10 a

nd 3

0kH

z on

the

fact

ory’

s m

ains

su

pply,

cau

sing

som

e pa

ckag

ing

mac

hine

s to

mal

func

tion

else

whe

re

on th

e si

te. F

igur

es 4

and

5 s

how

th

e m

ains

vol

tage

I m

easu

red

on th

e si

te w

hen

the

mac

hini

ng c

entre

was

ru

nnin

g. W

hen

it w

as n

ot ru

nnin

g, th

e m

ains

sup

ply

was

a n

ice

clea

n 50

Hz

sine

wav

e.

Figu

re 4

:O

ne p

eak

of th

e m

ains

cyc

le,

show

ing

the

10-3

0kH

z no

ise

Pea

k of

mai

ns w

avef

orm

, sho

win

g

nois

e ca

used

by

oper

atio

n of

new

m

achi

ning

cen

tre

Page 11: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

1415

safe

ty s

tand

ards

. The

site

cou

ld n

ot

be o

pera

ted

until

the

prob

lem

was

fi x

ed, w

hich

took

sev

eral

mon

ths

with

th

e co

st o

f los

t pro

duct

ion

runn

ing

at

abou

t £10

0,00

0 pe

r wee

k.

Figu

re 6

sho

ws

som

e of

the

nois

es

crea

ted

by th

ese

pow

erfu

l driv

es,

befo

re th

eir m

ains

em

issi

ons

wer

e su

ppre

ssed

.

0.00

0

-200

.0

-400

.0

-600

.0

200.

0

400.

0

600.

0

V

40 30 20

V1 W

avef

orm

346.

38 V

rms,

13.

35%

TH

D

Red

, blu

e an

d bl

ack

are

the

thre

e ph

ases

,an

d th

e gr

een

trac

e is

the

eart

h/gr

ound

All

of th

em s

uffe

ring

over

100

V p-

p of

nois

e at

the

2kH

z ch

oppi

ng fr

eque

ncy

of th

e ne

arly

1M

W V

FD10 0

15

1015

2025

3035

4045

50

Figu

re 6

: Vo

ltage

noi

ses

on th

e si

te’s

3-p

hase

mai

ns s

uppl

y, d

ue to

one

PD

S

volts

and

ran

hotte

r. (In

cide

ntal

ly,

the

repl

acem

ent fi

lter

was

the

one

reco

mm

ende

d by

the

VFD

m

anuf

actu

rer,

so th

e fa

ult l

ay w

ith th

e m

achi

ning

cen

tre m

anuf

actu

rer,

not

the

VFD

man

ufac

ture

r.)

The

man

ufac

ture

r of t

he m

achi

ning

ce

ntre

had

sav

ed a

few

£ b

y us

ing

a ch

eape

r fi lt

er th

an th

e on

e re

com

men

ded,

but

this

cau

sed

sign

ifi ca

nt fi

nanc

ial l

osse

s fo

r the

ir cu

stom

er, a

nd th

ey a

lso

had

to s

pend

a

cons

ider

able

am

ount

them

selv

es

on fi

eld

serv

ice

visi

ts to

dea

l with

th

e cu

stom

er’s

com

plai

nts

over

se

vera

l mon

ths,

and

eve

ntua

lly fi

x th

e pr

oble

m w

hen

I sho

wed

them

wha

t it

was

. Ove

rall,

it w

ould

hav

e be

en

muc

h m

ore

cost

-effe

ctiv

e to

hav

e sh

ippe

d th

e pr

oduc

t with

the

bette

r fi l

ter.

Sin

ce th

e m

achi

ning

cen

tre it

self

sold

for o

ver £

1 m

illio

n, w

hy ta

ke

such

a ri

sk ju

st to

sav

e on

e or

two

hund

red

£ on

the

chea

per m

ains

fi l

ter?

Unf

ortu

nate

ly, th

at is

how

m

ost m

anuf

actu

ring

com

pani

es

are

man

aged

thes

e da

ys, w

ith

good

eng

inee

ring

prac

tices

mad

e su

bser

vien

t to

crud

e an

alys

es o

f BO

M

cost

[23]

, ofte

n re

sulti

ng in

sig

nifi c

ant

fi nan

cial

risk

s, a

s pr

oved

by

this

ex

ampl

e.

It is

inte

rest

ing

to n

ote

that

alth

ough

th

e m

achi

ning

cen

tre w

ith th

e or

igin

al fi

lter m

et th

e em

issi

ons

limits

w

hen

test

ed to

EN

/IEC

618

00-3

,

it di

d no

t act

ually

com

ply

with

the

EM

C D

irect

ive

[2] [

7] b

ecau

se it

ca

used

una

ccep

tabl

e in

terfe

renc

e to

ot

her e

quip

men

t whe

n in

stal

led

as

reco

mm

ende

d by

its

man

ufac

ture

r, an

d so

did

not

com

ply

with

the

Dire

ctiv

e’s

Ess

entia

l Req

uire

men

ts,

see

[3].

3.5.

A s

econ

d ex

ampl

e of

the

fi nan

cial

risk

s of

inad

equa

te

EMC

eng

inee

ring

This

exa

mpl

e co

ncer

ns h

eavy

in

dust

ry, w

ith a

com

pany

that

bui

lt,

owne

d an

d op

erat

ed in

stal

latio

ns th

at

used

PD

Ss

rate

d at

nea

rly 1

MW

. The

B

DM

s th

ey p

urch

ased

wer

e no

t fi tt

ed

with

mai

ns fi

lters

, and

sin

ce th

ey h

ad

neve

r suf

fere

d fro

m a

ny s

igni

fi can

t pr

oble

ms,

whi

ch w

ere

iden

tifi e

d as

bei

ng c

ause

d by

EM

I, in

thei

r in

stal

latio

ns, t

hey

felt

that

igno

ring

the

cost

s of

sup

pres

sing

the

emis

sion

s fro

m th

ese

very

pow

erfu

l mot

or d

rives

w

as ju

stifi

ed.

If th

ey e

ven

knew

that

this

was

not

go

od E

MC

eng

inee

ring

prac

tice,

they

ne

verth

eles

s ig

nore

d it

beca

use

it w

as

appa

rent

ly s

avin

g th

em m

oney

.

But

rece

ntly

(at t

he ti

me

of w

ritin

g),

one

of th

eir n

ew in

stal

latio

ns d

id s

uffe

r fro

m E

MI w

ith it

s co

ntro

l ele

ctro

nics

, w

ith p

oten

tially

leth

al s

afet

y ris

ks fo

r an

yone

nea

r to

the

mac

hine

ry b

eing

co

ntro

lled.

Als

o, th

e gr

ound

noi

se

volta

ges

exce

eded

thos

e al

low

ed b

y

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1617

4. E

mis

sion

s

4.1.

The

bas

ic s

truc

ture

of a

B

DM

Figu

re 7

sho

ws

the

basi

c “b

lock

di

agra

m” o

f the

BD

M fo

r a V

FD fo

r an

AC

mot

or. I

t is

basi

cally

just

a m

ains

re

ctifi

er th

at p

rodu

ces

a D

C s

uppl

y (o

ften

calle

d a

“DC

-Lin

k”),

follo

wed

by

a p

ulse

-wid

th-m

odul

ated

(PW

M)

pow

er s

witc

hing

circ

uit (

ofte

n ca

lled

a ch

oppe

r, sw

itche

r or i

nver

ter)

. S

omet

imes

the

term

s ch

oppe

r, sw

itche

r or i

nver

ter a

re a

pplie

d to

the

who

le B

DM

incl

udin

g th

e re

ctifi

er. I

n a

low

-pow

er V

FD (<

10kW

), th

e ch

oppe

r m

ight

use

“Pow

erFE

T” d

evic

es, b

ut

alm

ost a

ll hi

gher

pow

er c

hopp

ers

use

IGB

Ts (I

nsul

ated

Gat

e B

ipol

ar

Tran

sist

ors)

inst

ead.

Any

DC

or A

C w

avef

orm

can

be

synt

hesi

sed

by c

hopp

ing

at a

hig

her

frequ

ency

(mus

t be

at le

ast t

wic

e th

e w

ante

d fre

quen

cy) b

y va

ryin

g its

mar

k:sp

ace

(i.e.

on:

off)

ratio

. C

hopp

ing

does

n’t w

aste

muc

h en

ergy

as

hea

t, w

hich

is w

hy P

WM

driv

es

are

muc

h sm

alle

r and

less

cos

tly, a

nd

mor

e ef

fi cie

nt, t

han

prev

ious

mot

or

spee

d co

ntro

l tec

hnol

ogie

s, a

nd w

hy it

is

so

popu

lar.

L1 L2 L3

M 3

Cho

pper

also

cal

led

switc

her

or in

verte

r

DC

Link

Rec

tifi

er6-

Pul

se ty

pesh

own

here

AC

Mot

orM

ains

Sup

ply

Figu

re 7

: B

lock

dia

gram

of a

VFD

for a

n A

C m

otor

It tu

rned

out

that

the

cost

of t

he

lost

pro

duct

ion

on th

is o

ne n

ew s

ite

was

man

y tim

es la

rger

than

the

com

pany

wou

ld h

ave

incu

rred

if it

had

al

way

s in

stal

led

PD

Ss

usin

g go

od

EM

C e

ngin

eerin

g pr

actic

es (w

hich

m

eans

usi

ng m

ains

fi lte

rs, s

ee la

ter)

. Th

is is

stil

l tru

e ev

en w

hen

usin

g a

disc

ount

ed c

ash-

fl ow

ana

lysi

s th

at

take

s th

e co

st o

f bor

row

ing

the

extra

m

oney

for t

he e

arlie

r, ap

pare

ntly

tro

uble

-free

inst

alla

tions

into

acc

ount

.

This

just

goe

s to

sho

w th

at w

e ca

n’t

beat

Mur

phy’

s La

w –

“If a

thin

g ca

n go

w

rong

, it w

ill”.

We

mig

ht th

ink

we

are

getti

ng a

way

with

poo

r eng

inee

ring

and

savi

ng m

oney

as

a re

sult,

but

(ju

st li

ke g

ambl

ing)

our

luck

can

not

hold

for e

ver.

In th

e en

d w

e w

ill b

e w

orse

off

than

if w

e ha

d al

way

s do

ne

good

eng

inee

ring.

For

mor

e on

why

M

urph

y’s

Law

is a

ctua

lly tr

ue (a

t lea

st

in p

art),

see

[27]

.

The

only

situ

atio

n w

here

this

“rul

e”

does

n’t a

pply,

is if

you

r com

pany

ha

s no

bra

nd im

age

and

is h

appy

to

sup

ply

peop

le w

ith ru

bbis

h an

d th

en “d

isap

pear

” (e.

g. b

y ch

angi

ng

nam

es) s

o as

not

to h

ave

to d

eal w

ith

the

resu

lting

hig

h w

arra

nty

cost

s.

Ther

e is

alw

ays

som

eone

will

ing

to

buy

from

an

unkn

own

man

ufac

ture

r, if

they

hav

e th

e lo

wes

t pric

e, s

o th

ere

is a

lway

s a

mar

ket f

or s

uch

man

ufac

ture

rs. I

’m s

ure

it w

ill c

ome

as n

o su

rpris

e th

at th

is G

uide

is n

ot

inte

nded

for u

se b

y su

ch c

ompa

nies

.

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1819

The

shar

per t

he e

dges

of t

he P

WM

, th

e hi

gher

the

frequ

ency

rang

e of

th

e em

issi

ons.

Fig

ure

10 s

how

s an

exa

mpl

e of

the

wav

efor

m a

nd

frequ

ency

spe

ctru

m o

f a 1

6kH

z sq

uare

wav

e (i.

e. a

ver

y si

mpl

e, 1

:1

mar

k-sp

ace

ratio

PW

M) w

ith 2

μs ri

se

and

fall

times

. The

ana

lysi

s of

the

squa

rew

ave

in te

rms

of fr

eque

ncy

show

s th

at m

ost o

f its

ene

rgy

is a

t the

16

kHz

switc

hing

rate

, and

that

it a

lso

has

sign

ifi ca

nt e

nerg

y at

all

the

odd-

16kH

z sq

uare

-wav

e P

WM

with

2μs

rise

/fall

times

(whe

n m

easu

red

with

an

osci

llosc

ope)

2050

100

200

500

1,00

02,

000

kHz

dB0

-10

-20

-30

-40

-50

-60

Fundamental (16kHz)

3rd Harmonic of 16kHz

5th Harmonic of 16kHz

7th Harmonic

11th Harmonic9th Harmonic

etc...

The

sam

e w

avef

orm

whe

n m

easu

red

with

a s

pect

rum

ana

lyse

r

Figu

re 1

0:

Exam

ple

of fr

eque

ncy

cont

ent o

f a 1

6kH

z sq

uare

wav

e PW

M w

ith

2μs

rise

and

fall

times

A sq

uare

wav

e is

a s

peci

al c

ase

of

a ch

oppe

r out

put w

avef

orm

, and

ty

pica

l PW

M w

avef

orm

s ar

e ge

nera

lly

rect

angu

lar (

i.e. t

heir

mar

k:sp

ace

ratio

s ar

e us

ually

not

1:1

). Th

is

mea

ns th

at th

eir f

requ

ency

spe

ctra

al

so c

onta

in e

ven-

orde

r har

mon

ics

of th

eir c

hopp

ing

frequ

ency

(e.g

. 2nd

, 4th

, 6th, e

tc.).

It a

lso

mea

ns th

at th

e le

vels

of t

he v

ario

us h

arm

onic

s do

no

t sho

w th

e si

mpl

e gr

adua

l fal

l-of

f with

incr

easi

ng fr

eque

ncy

that

w

e se

e in

Fig

ure

10. S

ome

high

fre

quen

cy h

arm

onic

s m

ay h

ave

high

er

num

bere

d ha

rmon

ics,

for e

xam

ple

at:

48kH

z (3

rd h

arm

onic

)

80kH

z (5

th h

arm

onic

)

112k

Hz

(7th h

arm

onic

)

144k

Hz

(9th h

arm

onic

)

176k

Hz

(11th

har

mon

ic)

...et

c., a

ll th

e w

ay to

at l

east

1.

616M

Hz

(the

101st

har

mon

ic) a

nd

beyo

nd

Figu

re 8

is c

opie

d fro

m [2

8], a

nd

show

s a

sim

ple

exam

ple

of g

ener

atin

g a

sine

wav

e us

ing

PW

M. T

he id

ea

is th

at w

hen

aver

aged

ove

r a fe

w

switc

hing

cyc

les,

the

rapi

d ch

oppi

ng

of th

e w

avef

orm

bec

omes

a s

moo

th

AC

wav

efor

m. S

o w

hen

used

to d

rive

a m

otor

, the

hig

h in

duct

ance

in it

s w

indi

ngs

caus

es th

e m

otor

cur

rent

to

follo

w th

e av

erag

e va

lue

of th

e P

WM

vo

ltage

. In

the

exam

ple

of F

igur

e 8,

this

resu

lts in

a s

inew

ave

at th

e

frequ

ency

requ

ired

to d

rive

the

AC

m

otor

at t

he ro

tatio

nal s

peed

requ

ired.

Figu

re 9

sho

ws

an e

xam

ple

of a

PW

M

mot

or o

utpu

t mea

sure

d w

ith a

pow

er

qual

ity m

eter

, on

a 90

0kW

VFD

. B

ecau

se th

e m

easu

ring

inst

rum

ent

that

was

use

d ha

s a

band

wid

th o

f onl

y ab

out 5

kHz,

the

PW

M v

olta

ge s

igna

ls

in F

igur

e 9

are

“ave

rage

d” to

som

e ex

tent

and

do

not a

ppea

r as

squa

re o

r sh

arp-

edge

d as

they

real

ly a

re.

1.5

1.0

0.5 0

-0.5

-1.0

-1.5

05

1015

(ms)

20

VB

B(T), V(v)

Figu

re 8

:Ex

ampl

e of

PW

M u

sed

to

crea

te a

sin

ewav

e

Figu

re 9

:Exa

mpl

e of

PW

M o

utpu

t of a

900

kW V

FD, m

easu

red

with

a 5

kHz

band

wid

th

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2021

The

curr

ent w

avef

orm

of a

linea

r loa

d, s

uppl

ied

from

asi

new

ave

volta

ge

The

non-

linea

r cur

rent

wav

efor

m ty

pica

lof

a s

ingl

e-ph

ase

phas

e-an

gle-

cont

rolle

dtr

iac,

sup

plie

d fr

om a

sin

ewav

e vo

ltage

5015

025

035

045

0

50 H

z m

ains

sup

ply

A

Hz

... a

nd it

s fr

eque

ncy

spec

trum

5015

025

035

045

0

50 H

z m

ains

sup

ply

A

Hz

... a

nd a

n ex

ampl

e sp

ectr

um

etc

Figu

re 1

2:H

arm

onic

cur

rent

s in

a s

ingl

e-ph

ase

phas

e-an

gle-

cont

rolle

d tr

iac

brid

ge

In th

ree-

phas

e (o

ften

calle

d 6-

puls

e)

rect

ifi er

s an

d ph

ase-

angl

e co

ntro

lled

triac

s su

pplie

d fro

m a

goo

d qu

ality

si

new

ave

volta

ge, t

he “t

riple

n”

harm

onic

s (3

rd, 9

th, 1

5th,

etc

.) ca

ncel

ou

t alm

ost e

ntire

ly in

the

circ

uit.

H

owev

er, i

f the

re is

any

imba

lanc

e in

the

supp

ly v

olta

ges,

trip

lens

ar

e pr

oduc

ed.

Sim

ilarly

, for

mul

ti-pu

lse

syst

ems

(e.g

. 12

puls

e) a

ny

imba

lanc

es in

the

para

llele

d 6

puls

e re

ctifi

ers,

pha

se s

hift

trans

form

er

seco

ndar

y w

indi

ngs

resu

lts in

trip

lens

an

d ot

her u

nwan

ted

nois

e em

issi

ons

bein

g pr

oduc

ed.

4.2.

The

unw

ante

d no

ise

sour

ces

in a

BD

MTh

e ab

ove

disc

ussi

on h

as s

how

n th

at, i

n a

BD

M, r

ectifi

ers

gen

erat

e cu

rren

ts a

t the

mai

ns fr

eque

ncy

and

its h

arm

onic

s, a

nd c

hopp

ers

gene

rate

vo

ltage

s at

kH

z fre

quen

cies

plu

s th

eir

harm

onic

s –

even

up

to te

ns o

f MH

z.

ampl

itude

s th

an lo

wer

freq

uenc

y on

es.

A D

C m

otor

driv

e ca

n us

e P

WM

just

lik

e a

VFD

, it o

nly

requ

ires

the

PW

M

wav

efor

m to

be

such

that

the

mot

or

curr

ent a

vera

ges

to a

DC

cur

rent

in

stea

d of

to a

n A

C o

ne.

But

som

e ty

pes

of p

ower

ful A

C a

nd

DC

mot

or d

rives

use

thyr

isto

r or t

riac

devi

ces

switc

hed

on a

nd o

ff at

the

frequ

ency

of t

he m

ains

pow

er, i

nste

ad

of p

lain

rect

ifi er

s. T

hey

don’

t nee

d to

us

e a

DC

-Lin

k or

a c

hopp

er. P

hase

-an

gle-

cont

rolle

d tri

acs

are

used

to

gene

rate

a v

aria

ble

DC

vol

tage

, an

d ap

prop

riate

on/

off s

witc

hing

of

thyr

isto

rs c

an g

ener

ate

AC

at

frequ

enci

es a

t up

to 5

0% o

f the

mai

ns

supp

ly fr

eque

ncy

(thes

e ar

e ca

lled

cycl

ocon

verte

rs).

Rec

tifi e

rs, w

heth

er p

lain

or p

hase

-an

gle

cont

rolle

d, o

r cyc

loco

nver

ters

, ge

nera

te h

arm

onic

s of

thei

r sw

itchi

ng

frequ

ency

– w

hich

is th

e m

ains

– a

nd

so th

ey g

ener

ate

wha

t we

call

“mai

ns

harm

onic

s” to

dis

tingu

ish

them

from

ot

her s

witc

hing

har

mon

ics.

Figu

re 1

1 sh

ows

the

fi rst

few

ha

rmon

ics

of th

e cu

rren

t in

a si

ngle

-ph

ase

brid

ge re

ctifi

er, w

hils

t Fig

ure

12 s

how

s th

ose

for a

pha

se-a

ngle

-co

ntro

lled

sing

le-p

hase

rect

ifi er

(whi

ch

coul

d be

a V

SD

for a

DC

mot

or).

The

curr

ent w

avef

orm

of a

linea

r loa

d, s

uppl

ied

from

asi

new

ave

volta

ge

The

non-

linea

r cur

rent

wav

efor

m ty

pica

lof

a s

ingl

e-ph

ase

rect

ifier

-cap

acito

r inp

utA

C-D

C p

ower

con

vert

er,

supp

lied

from

a s

inew

ave

volta

ge

5015

025

035

045

0

50 H

z m

ains

sup

ply

A

Hz

... a

nd it

s fr

eque

ncy

spec

trum

5015

025

035

045

0

50 H

z m

ains

sup

ply

A

Hz

... a

nd a

n ex

ampl

e sp

ectr

um

etc

Figu

re 1

1: H

arm

onic

cur

rent

s in

a s

ingl

e-ph

ase

brid

ge re

ctifi

er

Page 15: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

2223

VFD

, the

mot

or d

raw

s its

ele

ctric

al

pow

er a

t the

AC

freq

uenc

y th

at

is s

ynth

esis

ed b

y th

e P

WM

of i

ts

chop

per,

and

as a

resu

lt th

e cu

rren

t in

the

DC

-Lin

k an

d th

e m

ains

cur

rent

de

man

d bo

th fo

llow

this

freq

uenc

y.

For e

xam

ple,

if a

VFD

is s

et to

39H

z,

then

whe

n dr

ivin

g its

load

ed m

otor

it

draw

s cu

rren

t fro

m th

e m

ains

at

39H

z. A

nd b

ecau

se m

ains

rect

ifi er

s ar

e sw

itchi

ng c

ircui

ts a

nd n

ot li

near

on

es, t

hey

gene

rate

har

mon

ics

of th

is

frequ

ency

too.

Thes

e lo

w-fr

eque

ncy

non-

fund

amen

tal-r

elat

ed (5

0Hz

in E

urop

e)

mai

ns c

urre

nts

are

calle

d m

ains

“in

terh

arm

onic

s”, a

nd ju

st li

ke m

ains

ha

rmon

ics

they

circ

ulat

e w

idel

y in

the

mai

ns d

istri

butio

n ne

twor

k,

caus

ing

exce

ss h

eatin

g an

d di

stor

ting

the

volta

ge w

avef

orm

. DC

driv

es

can

also

gen

erat

e in

terh

arm

onic

s to

som

e de

gree

, whe

n th

e lo

ad o

n th

eir m

otor

s, o

r the

ir m

otor

spe

ed,

fl uct

uate

s re

petit

ivel

y an

d ra

pidl

y.

Just

as

for m

ains

har

mon

ics,

[1] a

nd

othe

r sta

ndar

ds s

peci

fy te

sts

and

limits

for i

nter

harm

onic

em

issi

ons.

Inte

rhar

mon

ic e

mis

sion

s ar

e m

ade

mor

e co

mpl

ex b

y in

term

odul

atio

n w

ithin

the

mai

ns re

ctifi

er. T

he m

ains

vo

ltage

freq

uenc

y an

d its

har

mon

ics

(dis

torte

d w

avef

orm

) int

erm

odul

ates

w

ith th

e A

C m

otor

driv

e fre

quen

cy

and

its h

arm

onic

s, to

cre

ate

a hu

ge

num

ber o

f “In

term

odul

atio

n P

rodu

cts”

. Fi

gure

13

show

s a

mea

sure

men

t tha

t

was

mad

e on

the

curr

ent s

pect

rum

of

a 70

0kW

VFD

, and

sho

ws

sign

ifi ca

nt

curr

ent l

evel

s at

, for

inst

ance

24A

at

103

.75H

z, w

hich

is s

ix ti

mes

the

mai

ns fr

eque

ncy

(nea

r to

50H

z) m

inus

fi v

e tim

es th

e m

otor

freq

uenc

y of

39

.4H

z.

The

gene

rato

rs u

sed

to p

rovi

de m

ains

po

wer

onl

y ge

nera

te a

t 50H

z (o

r 60

Hz)

, so

mai

ns h

arm

onic

cur

rent

s ar

e a

nuis

ance

. The

y ci

rcul

ate

wid

ely

in th

e m

ains

dis

tribu

tion

netw

ork

caus

ing

exce

ss h

eatin

g of

the

cabl

es,

indu

ctio

n m

otor

s, tr

ansf

orm

ers,

fuse

s an

d ci

rcui

t-bre

aker

s, a

nd a

s th

ey

fl ow

in th

e im

peda

nces

of t

he s

uppl

y ne

twor

k th

ey c

ause

vol

tage

dro

ps th

at

dist

ort t

he m

ains

wav

efor

m s

o th

at it

is

not

a c

lean

sin

ewav

e an

ymor

e. W

e sa

y th

at it

is h

arm

onic

ally

dis

torte

d,

and

whe

n vo

ltage

dis

torti

on le

vels

ris

e to

o hi

gh, m

any

kind

s of

ele

ctro

nic

equi

pmen

t can

mal

func

tion.

For

mor

e on

the

prob

lem

s of

mai

ns h

arm

onic

s,

see

[29]

and

[30]

, and

als

o th

e R

EO

G

uide

s on

EN

610

00-3

-2 a

nd E

N

6100

0-4-

13, f

rom

the

list a

t [4]

.

Sin

ce m

ains

har

mon

ics

do n

ot

cont

ribut

e to

del

iver

ed p

ower

(the

y ar

e ca

lled

“wat

tless

pow

er”,

wor

seni

ng

the

True

Pow

er F

acto

r – c

ombi

natio

n of

the

disp

lace

men

t pow

er fa

ctor

and

th

e di

stor

tion

fact

or o

f har

mon

ics)

, an

d si

nce

they

cau

se m

any

prob

lem

s,

we

cons

ider

them

to b

e an

unw

ante

d no

ise

emis

sion

. EN

/IEC

618

00-3

[1]

defi n

es te

sts

and

sets

lim

its fo

r the

em

issi

ons

of m

ains

har

mon

ics

from

a

PD

S, a

s do

EN

/IEC

610

00-3

-2 (f

or

ratin

gs u

p to

15A

/pha

se) a

nd E

N/IE

C

6100

0-3-

12 (f

or ra

tings

up

to 7

5A/

phas

e).

Mot

ors

have

too

muc

h m

echa

nica

l in

ertia

and

ele

ctric

al in

duct

ance

to

resp

ond

to k

Hz

chop

ping

freq

uenc

ies,

ne

ver m

ind

thei

r har

mon

ics

– bu

t the

y ca

n su

ffer i

ncre

ased

dow

ntim

e du

e to

th

eir i

nsul

atio

n fa

ilure

, mot

or b

earin

g pr

oble

ms

and

cabl

es b

eing

deg

rade

d by

the

high

freq

uenc

ies.

In

addi

tion,

in

duct

ion

mot

ors

with

dee

p ba

r or

doub

le c

age

desi

gn c

an o

verh

eat

sign

ifi ca

nt o

n he

avily

dis

torte

d su

pplie

s. O

n ex

plos

ion

proo

f (E

Exd

) m

otor

s w

ith th

ese

type

s of

roto

r de

sign

, the

fl am

epro

of s

eals

on

the

shaf

t, w

hich

are

des

igne

d to

con

tain

an

y in

tern

al e

xplo

sion

, can

bec

ome

degr

aded

, pos

sibl

y al

low

ing

any

inte

rnal

exp

losi

on to

be

trans

mitt

ed

outs

ide

the

mot

or c

arca

ss w

ith

poss

ibly

dis

astro

us c

onse

quen

ces.

If th

e ch

oppi

ng fr

eque

ncie

s an

d/or

th

eir h

arm

onic

s co

uple

with

oth

er

equi

pmen

t (vi

a co

nduc

tion,

indu

ctio

n or

radi

atio

n) th

ey c

an in

terfe

re

with

its

oper

atio

n. S

o it

is g

ood

engi

neer

ing

prac

tice

to tr

eat t

he

chop

ping

freq

uenc

y an

d its

har

mon

ics

as p

oten

tial s

ourc

e of

noi

se o

r de

grad

atio

n th

at s

houl

d be

con

trolle

d.

[1] s

peci

fi es

test

s an

d se

ts li

mits

for

the

amou

nt o

f con

duct

ed a

nd ra

diat

ed

emis

sion

s, in

com

mon

with

man

y ot

her E

MC

sta

ndar

ds, s

uch

as th

e ge

neric

em

issi

ons

stan

dard

s E

N/IE

C

6100

0-6-

3 an

d E

N/IE

C 6

1000

-6-4

.

So,

we

have

to li

mit

our P

DS

’s

emis

sion

s of

mai

ns h

arm

onic

s,

and

chop

per f

requ

enci

es a

nd th

eir

harm

onic

s. B

ut th

is is

not

all.

In a

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2425

and

volta

ge fl

uctu

atio

ns d

ue to

load

cu

rren

t cha

nges

; so

this

Gui

de w

ill

desc

ribe

the

tech

niqu

es th

at a

re u

sed

to c

ontro

l noi

se e

mis

sion

s fo

r VFD

s th

at u

se P

WM

. The

sam

e te

chni

ques

al

so w

ork

for t

hyris

tor a

nd tr

iac

driv

es, w

hich

will

pro

babl

y ne

ed m

ore

atte

ntio

n pa

ying

to s

uppr

essi

ng n

oise

em

issi

ons

in th

e lo

wer

freq

uenc

y ra

nge

(i.e.

bel

ow 1

50kH

z).

Varia

ble

spee

d m

otor

driv

es a

re a

lso

used

to d

rive

vario

us k

inds

of m

otor

s in

ser

vo s

yste

ms,

and

to d

rive

step

per

mot

ors.

The

se u

se th

e sa

me

DC

or

AC

PW

M m

otor

driv

e te

chno

logi

es

desc

ribed

abo

ve, s

o th

eir E

MC

sho

uld

be tr

eate

d th

e sa

me

way

.

Figu

re 1

4 sh

ows

how

the

nois

e cu

rren

ts fl

ow in

the

BD

M e

xam

ple

prev

ious

ly u

sed

in F

igur

e 7.

L1 L2 L3

Cho

pper

also

cal

led

switc

her

or in

verte

r

DC

Link

Rec

tifi

er6-

Pul

se ty

pesh

own

here

AC

Mot

orM

ains

Sup

ply

M 3 M

ains

har

mon

ics

and

DM

nois

e in

the

pow

er s

uppl

y

CM

noi

se d

ueto

the

rect

ifier

CM

noi

se d

ueto

the

chop

per

CM

noi

se fr

om re

ctifi

er a

nd c

hopp

erth

at a

lso

flow

s th

roug

h th

e D

C L

ink

PW

M o

utpu

t (ve

ryno

isy)

to th

e m

otor

This

sym

bol i

ndic

ates

inte

ntio

nal a

nd/o

r stra

y ca

paci

tanc

es to

thes

ite’s

ear

th/g

roun

d s

truct

ure

from

inte

rnal

com

pone

nts,

hea

tsin

ks, w

indi

ngs

etc.

(whe

ther

ext

erna

l cas

es/fr

ames

are

ear

thed

/gro

unde

d fo

r saf

ety

reas

ons

or n

ot)

To u

nder

stan

d Fi

gure

14,

we

have

to

unde

rsta

nd th

at th

ere

are

two

kind

s of

noi

se c

urre

nts

– di

ffere

ntia

l-mod

e (D

M) a

nd c

omm

on-m

ode

(CM

). A

ll cu

rren

ts fl

ow in

loop

s, a

nd D

M n

oise

cu

rren

ts fl

ow in

loop

s w

ithin

a s

ingl

e ca

ble

(or c

able

bun

dle)

. In

the

case

of

a th

ree-

phas

e de

lta c

onne

cted

V

FD li

ke th

at s

how

n in

Fig

ure

14, D

M

curr

ents

fl ow

out

and

bac

k al

ong

the

thre

e m

ains

pha

se c

ondu

ctor

s, a

nd

they

als

o fl o

w o

ut a

nd b

ack

alon

g th

e th

ree

mot

or p

hase

con

duct

ors.

How

ever

, CM

noi

se fl

ows

out a

long

all

of th

e co

nduc

tors

in a

cab

le o

r cab

le

bund

le a

t the

sam

e tim

e, a

nd re

turn

s vi

a a

diffe

rent

pat

h to

com

plet

e its

Figu

re 1

4:H

ow th

e no

ise

curr

ents

fl ow

in a

BD

M

The

rem

aind

er o

f thi

s G

uide

will

fo

cus

on V

FDs

and

VS

Ds

that

use

P

WM

, bec

ause

thes

e ar

e th

e w

orst

fo

r cre

atin

g hi

gh-fr

eque

ncy

nois

e em

issi

ons.

Thi

s is

bec

ause

thei

r ch

oppe

rs u

se v

ery

fast

-sw

itchi

ng

Pow

erFE

TS o

r IG

BTs

, whi

ch a

re

oper

ated

at k

Hz

switc

hing

rate

s –

as

low

as

1kH

z fo

r MW

pow

er ra

tings

; as

hig

h as

50k

Hz

for r

atin

gs a

roun

d 1k

W. W

e ca

n ex

pect

to h

ave

to

cont

rol n

oise

at f

requ

enci

es o

f up

to

1,00

0 tim

es th

e sw

itchi

ng ra

te (e

.g.

1MH

z fo

r a 1

kHz

chop

per,

50M

Hz

for

50kH

z).

Thyr

isto

rs a

nd tr

iacs

sw

itch

muc

h m

ore

slow

ly th

an P

ower

FETS

and

IG

BTs

, and

thei

r sw

itchi

ng ra

te is

no

high

er th

an th

e m

ains

freq

uenc

y. A

s a

resu

lt th

ey p

rodu

ce s

igni

fi can

tly

low

er le

vels

of h

igh-

frequ

ency

noi

se

emis

sion

s th

an a

PW

M d

rive

of th

e sa

me

pow

er ra

ting.

How

ever

, sin

ce

they

are

ofte

n us

ed a

t ver

y hi

gh

pow

ers,

thei

r hig

h-fre

quen

cy n

oise

em

issi

ons

can

be s

igni

fi can

t and

sh

ould

not

be

igno

red.

All

type

s of

VS

Ds

crea

te lo

w

frequ

ency

em

issi

ons

at h

arm

onic

s of

the

mai

ns s

uppl

y, in

terh

arm

onic

s,

From

Fig

ure

13 o

f: “P

ower

Sys

tem

Har

mon

ics,

Par

t 4: I

nter

harm

onic

s”R

. Yac

amin

i, IE

E P

ower

Jou

rnal

, Aug

ust 1

966

The

mot

or d

rive

frequ

ency

is 3

9.4H

z

Figu

re 1

3:Ex

ampl

e of

inte

rmod

ulat

ion

incr

easi

ng th

e in

terh

arm

onic

leve

ls in

a V

FD

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2627

13) t

he ra

tios

of c

urre

nts

betw

een

the

loop

s is

freq

uenc

y-de

pend

ent.

Sim

ply

put,

we

shou

ld e

xpec

t the

CM

noi

se

from

a P

DS

to fl

ow a

ll ov

er th

e ea

rth/

grou

nd s

truct

ure

of a

site

or a

ves

sel.

L1 L2 L3

Cho

pper

also

cal

led

switc

her

or in

verte

r

DC

Link

Rec

tifi

er6-

Pul

se ty

pesh

own

here

AC

Mot

or

M 3

Filte

r mus

t be

RF-

bond

ed to

the

chop

per’s

met

alen

clos

ure

Rec

tifie

r and

cho

pper

met

alen

clos

ures

mus

t be

RF-

bond

ed

Mai

nsIn

duct

orha

rmon

icsu

ppre

ssio

n

Mai

ns F

ilter

very

clo

seto

rect

ifier

nois

e su

ppre

ssio

nkH

z - M

Hz

Out

put

Indu

ctor

and/

or F

ilter

ver

ycl

ose

to c

hopp

erno

ise

supp

ress

ion

kHz

- MH

z

Now

muc

h re

duce

d ha

rmon

ics,

DM

and

CM

noi

ses

flow

in th

e lo

ng m

ains

cab

le

Mos

t CM

noi

ses

now

flow

in m

uch

smal

ler l

oops

with

in th

e fil

ter/d

rive/

filte

r ass

embl

y

Now

muc

h re

duce

d D

M

and

CM

noi

ses

flow

in th

e lo

ng m

ains

cab

le

DC

noi

se in

the

mai

ns s

uppl

yP

WM

out

put

(ver

y no

isy)

Filte

r mus

tbe

RF-

bond

edto

the

rect

ifier

’s

met

al e

nclo

sure

Figu

re 1

5: U

sing

indu

ctor

s an

d fi l

ters

to s

uppr

ess

nois

e em

issi

ons

4.3.

Sup

pres

sing

the

nois

e so

urce

sFi

gure

15

show

s th

e us

e of

fi lte

rs a

t th

e B

DM

’s re

ctifi

er’s

inpu

t, an

d at

its

chop

per’s

out

put,

to s

uppr

ess

the

DM

an

d C

M n

oise

em

issi

ons.

The

best

way

to u

nder

stan

d ho

w a

fi l

ter s

uppr

esse

s D

M a

nd C

M n

oise

em

issi

ons,

is to

rega

rd it

as

a m

eans

of

pro

vidi

ng a

retu

rn p

ath

for t

he n

oise

cu

rren

t loo

ps th

at h

as a

muc

h lo

wer

im

peda

nce

than

the

othe

r loo

ps. T

he

nois

e cu

rren

t will

then

aut

omat

ical

ly

split

so

that

mos

t of i

t fl o

ws

in th

e pa

th

prov

ided

by

the

fi lte

r. Fi

lters

gen

eral

ly

use

capa

cito

rs to

pro

vide

thes

e lo

w-

impe

danc

e lo

ops.

Mos

t fi lt

ers

also

add

indu

ctor

s an

d ch

okes

to in

crea

se th

e im

peda

nce

of th

e m

ains

or m

otor

cab

les

on “t

he

othe

r sid

e” a

fter t

he p

rovi

sion

of t

he

low

-impe

danc

e re

turn

pat

h, to

hel

p en

cour

age

mos

t of t

he n

oise

cur

rent

s to

fl ow

in th

e ne

w p

ath

prov

ided

by

the

fi lte

r and

not

out

into

the

inst

alla

tion’

s ca

bles

whe

re it

mig

ht

caus

e in

terfe

renc

e.

Figu

re 1

5 sh

ows

the

mai

ns h

arm

onic

em

issi

ons

from

the

rect

ifi er

bei

ng

supp

ress

ed b

y a

thre

e-ph

ase

indu

ctor

, a

com

mon

tech

niqu

e of

ten

calle

d a

line

reac

tor (

or ju

st re

acto

r). O

ther

m

etho

ds a

re d

iscu

ssed

late

r.

loop

. Any

pat

h w

ill d

o, b

ut th

e on

e th

at

alw

ays

exis

ts is

via

the

earth

/gro

und

stru

ctur

e of

the

site

or v

esse

l the

P

SD

is in

stal

led

in. E

ven

whe

re n

o co

nduc

tive

path

exi

sts,

hig

h-fre

quen

cy

curr

ents

can

eas

ily fl

ow th

roug

h th

e ai

r or i

nsul

ator

s, v

ia s

tray

mut

ual

indu

ctan

ces

and

stra

y ca

paci

tanc

es.

Figu

re 1

4 in

dica

tes

som

e of

the

stra

y ca

paci

tanc

es th

at e

xist

in a

typi

cal

PD

S, w

hich

can

car

ry C

M c

urre

nts.

CM

cur

rent

s ar

e ca

used

by

imba

lanc

es b

etw

een

stra

y ca

paci

tanc

es a

nd s

tray

indu

ctan

ces,

fo

r exa

mpl

e, th

e st

ray

capa

cita

nce

of P

hase

1 to

ear

th/g

roun

d, v

ersu

s th

at o

f Pha

se 2

. The

se im

bala

nces

ar

e sm

all,

so C

M n

oise

cur

rent

s ar

e sm

all w

hen

com

pare

d w

ith th

e D

M

nois

e cu

rren

ts, b

ut s

ince

CM

cur

rent

s tra

vel i

n ve

ry la

rge

loop

s, w

hich

can

en

com

pass

a w

hole

site

or v

esse

l, th

ey h

ave

the

pote

ntia

l to

caus

e as

m

uch

(or m

ore)

inte

rfere

nce

as D

M

curr

ents

.

Figu

re 1

4 sh

ows

(as

a do

uble

-he

aded

arr

ow) t

he D

M n

oise

cu

rren

ts a

ssoc

iate

d w

ith th

e re

ctifi

er

– co

nsis

ting

of m

ains

har

mon

ics

and

inte

rhar

mon

ics

plus

hig

h-fre

quen

cy

switc

hing

noi

ses

from

the

rect

ifi er

s th

emse

lves

– fl

owin

g in

the

thre

e-ph

ase

mai

ns c

able

’s c

ondu

ctor

s.

It al

so s

how

s (a

lso

as a

dou

ble-

head

ed a

rrow

) the

DM

noi

se c

urre

nts

asso

ciat

ed w

ith th

e ch

oppe

r –

cons

istin

g of

the

set m

otor

freq

uenc

y an

d its

har

mon

ics,

plu

s th

e ch

oppe

r fre

quen

cy a

nd it

s ha

rmon

ics

– fl o

win

g in

the

thre

e-ph

ase

mot

or c

able

’s

cond

ucto

rs.

Figu

re 1

4 sh

ows

– as

red

ellip

ses

– th

e C

M n

oise

cur

rent

loop

as

soci

ated

with

the

rect

ifi er

and

mai

ns

supp

ly, a

nd th

e lo

op a

ssoc

iate

d w

ith

the

chop

per a

nd th

e m

otor

. It a

lso

show

s a

larg

er e

llips

e in

dica

ting

that

re

ctifi

er C

M n

oise

als

o fl o

ws

in a

loop

th

at c

ompr

ises

the

mot

or, c

hopp

er

and

DC

-Lin

k; a

nd th

at c

hopp

er n

oise

al

so fl

ows

in a

loop

that

com

pris

es th

e m

ains

sup

ply,

rect

ifi er

and

DC

-Lin

k.

I’m s

ure

the

read

er w

ill a

ppre

ciat

e th

at

Figu

re 1

4 is

a g

ross

sim

plifi

catio

n fo

r th

e pu

rpos

e of

illu

stra

tion,

and

that

its

sim

plifi

ed a

naly

sis

can

equa

lly w

ell b

e ap

plie

d to

VFD

s us

ing

sing

le-p

hase

, or

six

(or m

ore)

pha

se re

ctifi

ers.

Cur

rent

s fl o

w a

ccor

ding

to th

e im

peda

nce

that

they

exp

erie

nce

arou

nd th

eir e

ntire

loop

, and

whe

re

ther

e is

mor

e th

an o

ne a

ltern

ativ

e pa

th th

ey w

ill ta

ke a

ll of

them

, div

idin

g be

twee

n th

em in

a ra

tio th

at d

epen

ds

upon

the

impe

danc

es o

f eac

h, a

nd th

e fre

quen

cy c

once

rned

.

Stra

y ca

paci

tanc

e en

sure

s th

at th

ere

are

alw

ays

man

y al

tern

ativ

e lo

ops

for C

M c

urre

nts

to fl

ow in

, and

sin

ce

ther

e ar

e ve

ry m

any

nois

e fre

quen

cies

as

soci

ated

with

rect

ifi er

s an

d ch

oppe

rs (s

ee F

igur

es 1

0, 1

1, 1

2 an

d

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2829

Figu

re 1

6 sh

ows

an e

xam

ple

of a

50

kW V

FD a

ssem

bled

in a

n in

dust

rial

cabi

net w

ith it

s m

ains

fi lte

r. N

ote

how

clo

se th

e m

ains

fi lte

r is

to th

e V

FD’s

rect

ifi er

, and

als

o ho

w b

oth

the

cond

uctiv

ely-

plat

ed m

etal

bod

ies

of th

e fi l

ter,

rect

ifi er

and

cho

pper

un

its a

re a

ll m

ulti-

poin

t bon

ded

to

the

cabi

net’s

con

duct

ivel

y-pl

ated

ba

ckpl

ate,

to p

rovi

de g

ood

RF-

bond

ing

up to

sev

eral

10s

of M

Hz.

Figu

re 1

5 sh

ows

how

this

app

roac

h re

duce

s P

DS

em

issi

ons,

by

show

ing

that

the

doub

le-h

eade

d ar

row

s of

th

e D

M n

oise

cur

rent

s, a

nd th

e re

d el

lipse

s of

the

CM

noi

se c

urre

nts,

are

al

l now

con

tain

ed w

ithin

the

asse

mbl

y co

mpr

isin

g th

e m

ains

fi lte

r, V

FD a

nd

outp

ut fi

lter.

They

are

not

sho

win

g as

fl o

win

g in

eith

er th

e m

ains

sup

ply

or

mot

or c

able

s.

See

4.4

.4 fo

r usi

ng a

n is

olat

ing

trans

form

er to

impr

ove

the

CM

pe

rform

ance

of m

ains

fi lte

rs, a

nd –

w

here

CM

noi

se is

the

only

sig

nifi c

ant

prob

lem

– p

ossi

bly

repl

acin

g th

e m

ains

fi lte

r ent

irely.

Figu

re 1

6:

Exam

ple

of a

50k

W d

rive

with

fi lte

red

mai

ns a

nd s

cree

ned

mot

or c

able

Mai

ns F

ilter

Mai

ns Is

olat

or

Filte

r, in

duct

or, r

ectifi

er a

nd c

hopp

er a

ll ha

ve m

etal

en

clos

ures

, are

all

clos

e to

geth

er, a

nd a

re a

ll m

ulti-

poin

t RF-

bond

ed to

one

con

duct

ivel

y-pl

ated

met

al b

ack-

plat

e

Mai

ns

Indu

ctor

s

50kW

VS

D C

hopp

er

Scr

eene

d m

otor

cab

le’s

scr

een

term

inat

ion

at c

hopp

er

50kW

VS

D R

ectifi

er

Not

e th

at F

igur

e 15

sho

ws

line

reac

tor

fi tte

d to

the

supp

ly s

ide

of th

e m

ains

fi l

ter,

not t

o its

BD

M s

ide,

bec

ause

th

is h

elps

pre

vent

reso

nanc

es in

the

mai

ns p

ower

dis

tribu

tion

netw

ork.

C

onne

ctin

g ca

paci

tors

dire

ctly

to

a su

pply

net

wor

k, w

ithou

t ser

ies

reac

tors

bet

wee

n th

em a

nd th

e su

pply,

has

bee

n se

en to

cau

se

reso

nanc

es th

at c

ause

d co

stly

da

mag

e to

equ

ipm

ent,

with

eve

n hi

gher

cos

ts d

ue to

its

dow

ntim

e.

Pro

vidi

ng a

low

-impe

danc

e pa

th fo

r D

M n

oise

cur

rent

s is

eas

y –

sim

ply

conn

ect c

apac

itors

bet

wee

n th

e ph

ase

cond

ucto

rs in

eac

h ca

ble.

Th

ese

will

tend

to “s

hort

out”

the

DM

cu

rren

ts, s

o th

ey d

on’t

get o

ut in

to th

e su

pply

or m

otor

cab

le, b

ut o

f cou

rse

no c

apac

itor i

s pe

rfect

so

the

nois

e cu

rren

t red

irect

ion

is n

ot p

erfe

ct e

ither

an

d so

me

DM

noi

se c

urre

nt w

ill s

till

fl ow

in th

e lo

ng c

able

s.

Red

irect

ing

the

CM

cur

rent

s al

so

uses

cap

acito

rs, b

ut th

ey h

ave

to

be c

onne

cted

to th

e ea

rth/g

roun

d st

ruct

ure,

so

to b

e ef

fect

ive

the

impe

danc

e in

the

earth

/gro

und

stru

ctur

e be

twee

n th

e fi l

ter a

nd th

e re

ctifi

er o

r cho

pper

mus

t be

very

sm

all

inde

ed. T

his

esse

ntia

lly m

eans

:

Loca

te th

e in

duct

ors

and/

or

fi lte

rs p

hysi

cally

as

clos

e as

pr

actic

able

to th

e un

it w

hose

no

ise

it is

to s

uppr

ess

(i.e.

the

rect

ifi er

or t

he c

hopp

er)

RF-

bond

the

met

al b

odie

s of

the

indu

ctor

s or

fi lte

rs to

the

met

al

body

of t

he u

nit w

hose

noi

se it

is

to s

uppr

ess.

(Eve

n th

ough

an

indu

ctor

has

no

inte

ntio

nal p

ath

to e

arth

/gro

und,

like

th

e ca

paci

tors

in a

fi lte

r, its

win

ding

s ha

ve s

igni

fi can

t stra

y ca

paci

tanc

e w

hich

will

hel

p co

ntro

l CM

cur

rent

s,

prov

idin

g th

e in

duct

or is

RF-

bond

ed.)

“RF-

bond

ing”

mea

ns p

rovi

ding

a

cond

uctiv

e pa

th th

at h

as a

ver

y lo

w im

peda

nce,

<<1

00m

Ω, a

t the

fre

quen

cy c

once

rned

. Ide

ally,

the

cond

uctiv

e pa

th s

houl

d ha

ve a

n im

peda

nce

of 1

or l

ess

at th

e hi

ghes

t fre

quen

cy th

at it

is d

esire

d to

con

trol.

Rem

embe

r tha

t thi

s is

the

impe

danc

e of

a b

ond,

not

sim

ply

its

resi

stan

ce.

Wire

s or

bra

id s

traps

are

inef

fect

ive

for R

F-bo

ndin

g pu

rpos

es, b

ecau

se

thei

r im

peda

nce

is to

o gr

eat.

The

indu

ctiv

e im

peda

nce

of a

stra

ight

wire

is

2�ƒ

L, w

here

ƒ is

the

frequ

ency

to

be s

uppr

esse

d in

Her

tz (H

z) a

nd L

is

the

indu

ctan

ce o

f the

wire

in H

enrie

s (H

). W

e ca

n as

sum

e ab

out 1

μH/m

etre

fo

r a lo

ng w

ire a

nd a

bout

0.3

μH/m

etre

fo

r a w

ide

brai

d st

rap,

so,

for e

xam

ple,

at

1M

Hz

a 25

mm

wid

e br

aid

stra

p ju

st 1

00m

m lo

ng th

at m

ight

hav

e a

resi

stan

ce o

f 1m

Ω h

as a

n im

peda

nce

of n

early

0.2

Ω a

t 1M

Hz

– 20

to 2

00

times

too

high

to b

e a

good

RF-

bond

.

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3031

of h

igh-

frequ

ency

noi

ses.

Eve

n w

here

the

chop

per d

oes

not

caus

e in

terfe

renc

e pr

oble

ms,

ther

e is

th

e pr

oble

m o

f bea

ring

life,

and

of t

he

degr

adat

ion

of th

e in

sula

tion

in m

otor

ca

bles

and

win

ding

s w

hen

long

mot

or

cabl

es a

re u

sed

(see

3.3

).Fig

ure

18

show

s an

alte

rnat

ive

to th

e ou

tput

fi l

ter s

how

n in

Fig

ure

15 –

a s

cree

ned

mot

or c

able

. As

this

fi gu

re s

how

s,

if th

e sc

reen

ed m

otor

cab

le h

as it

s sc

reen

cor

rect

ly R

F-bo

nded

at b

oth

ends

, the

CM

cur

rent

loop

s as

soci

ated

w

ith th

e V

FD’s

mot

or o

utpu

t pre

fer

to fl

ow in

side

the

cabl

e sc

reen

. Thi

s

is b

ecau

se th

e im

peda

nce

of th

e C

M

loop

pat

h do

wn

the

insi

de o

f the

cab

le

scre

en is

so

muc

h lo

wer

than

the

alte

rnat

ive

CM

loop

s th

at e

xist

in th

e ea

rth/g

roun

d st

ruct

ure.

For e

xam

ple,

whe

n a

num

ber o

f re

sist

ors

are

conn

ecte

d in

par

alle

l, it

is th

e on

e(s)

with

the

low

est v

alue

th

at c

arry

the

bulk

of t

he c

urre

nt.

The

impe

danc

e of

the

CM

loop

s at

fre

quen

cies

abo

ve a

kH

z or

so

are

dom

inat

ed b

y in

duct

ive

and

capa

citiv

e re

acta

nces

, rat

her t

han

resi

stan

ce,

but t

he s

ame

prin

cipl

e ap

plie

s –

the

bulk

of t

he C

M c

urre

nt a

utom

atic

ally

L1 L2 L3

Cho

pper

also

cal

led

switc

her

or in

verte

r

DC

Link

Rec

tifi

er6-

Pul

se ty

pesh

own

here

AC

Mot

or

M 3

“RF

bond

ed”:

to th

ech

oppe

r’s m

etal

enc

losu

reat

one

end

; and

to th

em

otor

fram

e at

the

term

inal

box

at t

he o

ther

end

Rec

tifie

r and

cho

pper

met

alen

clos

ures

mus

t be

RF-

bond

ed

Mai

nsIn

duct

orha

rmon

icsu

ppre

ssio

n

Mai

ns F

ilter

very

clo

seto

rect

ifier

nois

e su

ppre

ssio

nkH

z - M

Hz

Now

muc

h re

duce

d ha

rmon

ics,

DM

and

CM

noi

ses

flow

in th

e lo

ng m

ains

cab

le

Mos

t CM

noi

ses

now

flow

in m

uch

smal

ler l

oops

with

in th

e fil

ter/d

rive/

cabl

e as

sem

bly

The

DM

and

CM

noi

ses

flow

ing

in th

e lo

ng m

otor

ca

ble

mos

tly s

tay

insi

de it

DC

noi

se in

the

mai

ns s

uppl

yP

WM

noi

se c

onta

ined

with

in c

able

Filte

r mus

tbe

RF-

bond

edto

the

rect

ifier

’s

met

al e

nclo

sure

Scr

eene

d ca

ble,

or u

nscr

eene

d ca

ble

with

an

over

brai

d,or

with

a s

hiel

ding

cond

uit a

nd/o

rca

ble

arm

our

Figu

re 1

8:Su

ppre

ssio

n w

ith m

ains

indu

ctor

s an

d fi l

ters

, and

scr

eene

d m

otor

cab

les

I don

’t ha

ve a

real

-life

pho

togr

aph

of

an o

utpu

t fi lt

er in

stal

led

on a

VFD

, but

th

e pr

inci

ples

are

exa

ctly

the

sam

e as

for t

he m

ains

fi lte

r in

Figu

re 1

6.

The

outp

ut fi

lter s

houl

d be

one

that

, lik

e th

e m

ains

fi lte

r, re

dire

cts

both

the

DM

and

CM

noi

se c

urre

nts

that

wou

ld

othe

rwis

e fl o

w in

the

mot

or c

able

and

m

otor

, suc

h as

the

RE

O “S

inus

++”

, ot

herw

ise

know

n as

fi lte

r typ

e C

NW

961.

Fig

ure

15 d

oes

not s

how

it, b

ut

CM

+ D

M o

utpu

t fi lt

ers

like

the

CN

W

961

gene

rally

requ

ire a

con

nect

ion

to

the

DC

-Lin

k as

wel

l.

Figu

re 1

7 sh

ows

som

e re

al-li

fe

mea

sure

men

ts o

n a

VFD

fi tte

d w

ith

serie

s in

duct

ors

to li

mit

emis

sion

s of

mai

ns h

arm

onic

s, th

en w

ith a

n ad

ditio

nal fi

lter

to s

uppr

ess

emis

sion

s

RE

O c

ompo

nent

s ar

e av

aila

ble

that

com

bine

serie

s in

duct

ors

with

mai

ns fi

lters

VFD

mai

ns c

urre

ntsh

owin

g ha

rmon

ic n

oise

VFD

mai

ns v

olta

gesh

owin

g R

F no

ise

And

add

ing

a fil

ter r

educ

es th

eR

F no

ise

on th

e m

ains

vol

tage

Add

ing

a se

ries

indu

ctor

redu

ces

the

mai

ns h

arm

onic

cur

rent

s

Figu

re 1

7:Ex

ampl

es o

f sup

pres

sing

mai

ns n

oise

s

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3233

Figu

re 1

9:D

etai

l of t

he m

otor

cab

le c

onne

ctio

n to

the

chop

per i

n Fi

gure

16

Bra

id-s

cree

ned

mot

or c

able

’s s

cree

n te

rmin

atio

n at

cho

pper

Use

s a

met

al s

addl

ecla

mp

that

bon

ds

to a

wid

e fl a

nge

exte

ndin

g fro

m th

e ch

assi

s of

the

chop

per’s

ele

ctro

nics

50kW

VS

D

Cho

pper

take

s th

e lo

op th

at p

rese

nts

the

leas

t ov

eral

l im

peda

nce.

To a

chie

ve th

e lo

w im

peda

nce

nece

ssar

y to

con

trol t

he m

otor

ou

tput

’s C

M c

urre

nts:

At t

he c

hopp

er e

nd, t

he m

otor

ca

ble

scre

en m

ust b

e R

F-bo

nded

to th

e ch

oppe

r’s m

etal

en

clos

ure,

cha

ssis

or f

ram

e.

At t

he m

otor

end

, the

mot

or

cabl

e sc

reen

mus

t be

RF-

bond

ed to

the

mot

or’s

met

al

term

inal

box

, whi

ch in

turn

mus

t be

RF-

bond

ed to

the

mot

or’s

en

clos

ure

or fr

ame

(e.g

. by

seam

-wel

ding

or m

ultip

le s

pot o

r ta

ck w

elds

).

Not

e: F

igur

e 18

doe

s no

t sho

w a

n ea

rth/g

roun

d ca

ble

betw

een

the

mot

or

body

and

the

chop

per,

alth

ough

one

w

ill a

lmos

t cer

tain

ly b

e re

quire

d. T

his

is b

ecau

se s

ome

VFD

man

ufac

ture

rs

requ

ire it

to b

e co

ntai

ned

with

in th

e sc

reen

of a

scr

eene

d m

otor

cab

le,

whe

reas

oth

er m

anuf

actu

rers

requ

ire

it to

be

rout

ed o

utsi

de th

e sc

reen

(but

st

ill c

lose

to th

e m

otor

cab

le a

long

its

rout

e). T

hese

requ

irem

ents

com

e fro

m th

e el

ectro

nic

desi

gn o

f the

V

FD, s

o it

is im

porta

nt to

obt

ain

the

man

ufac

ture

r’s E

MC

inst

ruct

ions

for

the

exac

t mod

el o

f mot

or d

rive,

and

fo

llow

them

.

A go

od w

ay to

pre

vent

noi

se fr

om

the

chop

per w

hich

is c

ausi

ng E

MC

prob

lem

s, is

to m

ake

the

mot

or

cabl

e ve

ry s

hort

inde

ed –

less

than

on

e-te

nth

of th

e w

avel

engt

h at

the

high

est s

igni

fi can

t cho

pper

har

mon

ic

frequ

ency

(e.g

. 1m

for 3

0MH

z, 1

0m

for 3

MH

z, 1

00m

for 3

00kH

z). T

he

very

bes

t is

to c

ombi

ne th

e B

DM

with

th

e m

otor

, with

thei

r met

al fr

ames

m

ulti-

poin

t RF-

bond

ed to

geth

er,

or c

ombi

ned

in a

com

mon

cas

ting,

so

ther

e is

no

exte

rnal

mot

or c

able

at

all.

Thi

s te

chni

que

has

been

ve

ry s

ucce

ssfu

lly u

sed

by s

ome

man

ufac

ture

rs, i

nclu

ding

Dan

foss

.

All

VFD

and

VS

D m

anuf

actu

rers

sh

ould

pro

vide

det

aile

d E

MC

in

stru

ctio

ns fo

r the

ir pr

oduc

ts. I

do

not

reco

mm

end

usin

g an

y m

anuf

actu

rer

who

doe

s no

t (or

will

not

) pro

vide

th

em. T

hey

will

ofte

n be

diff

eren

t for

di

ffere

nt m

odel

s an

d ra

tings

of d

rives

, an

d fo

r exa

mpl

e, h

ighe

r rat

ed d

rives

w

ill g

ener

ally

requ

ire d

iffer

ent fi

lter

sp

ecifi

catio

ns.

Cab

le s

cree

n R

F-bo

ndin

g is

so

met

imes

cal

led

360°

term

inat

ion

or 3

60°

bond

ing,

bec

ause

it s

houl

d id

eally

mak

e el

ectri

cal c

onne

ctio

n al

l ar

ound

the

circ

umfe

renc

e or

per

iphe

ry

of th

e br

aid

scre

en. A

ltern

ativ

es, s

uch

as m

ulti-

poin

t bon

ding

, may

be

used

pr

ovid

ing

the

bond

ing

poin

ts s

urro

und

the

cabl

e.

Figu

re 1

9 sh

ows

an a

mpl

ifi ed

det

ail

of F

igur

e 16

, whe

re th

e m

otor

cab

le

conn

ects

to th

e 50

kW V

FD’s

cho

pper

un

it. It

sho

ws

that

the

cabl

e’s

brai

d is

cl

ampe

d to

a fl

ange

pro

trudi

ng fr

om

the

chop

per’s

cha

ssis

, usi

ng a

met

al

sadd

lecl

amp.

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3435

Figu

re 2

1:Ex

ampl

es o

f thr

ee k

inds

of E

MC

cab

le g

land

A lo

w-c

ost E

MC

Gla

nd fr

om H

umm

el(r

equi

res

the

shie

ld to

be

cut a

nd

care

fully

spr

ead

out,

so is

not

gen

eral

ly

appl

icab

le a

nd is

als

o su

scep

tible

to

qual

ity o

f wor

kman

ship

A hi

gh q

ualit

y ca

ble

glan

d fro

m

KE

C(u

ses

an ir

is s

prin

g to

mak

e an

ex

celle

nt R

F-bo

nd An

EM

C G

land

from

La

pp K

abel

(mul

ti-po

int s

hiel

d co

nnec

tion)

Figu

re 2

0 sh

ows

the

othe

r end

of t

he

mot

or c

able

in th

e sy

stem

driv

en b

y th

e V

FD in

Fig

ure

16. H

ere

the

mot

or

cabl

e’s

brai

d us

es a

n “E

MC

Gla

nd”

to 3

60°

bond

to th

e m

otor

’s te

rmin

al

box.

Fig

ure

21 s

how

s a

varie

ty o

f

type

s of

EM

C g

land

, the

top

left-

hand

on

e be

ing

the

pref

erre

d ty

pe. W

here

co

nnec

tors

are

use

d in

stea

d, th

ey

shou

ld te

rmin

ate

the

cabl

e sc

reen

in

360°

just

like

an

EM

C g

land

.

Figu

re 2

0:D

etai

l of t

he c

able

con

nect

ion

to th

e m

otor

driv

en b

y th

e VF

D o

f Fig

ure

16

Bra

id-s

cree

ned

mot

or c

able

’s s

cree

n te

rmin

atio

n at

mot

orU

ses

a 36

0O sc

reen

-bon

ding

cab

le

glan

d

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3637

Figu

res

15 a

nd 1

8 sh

ow th

e D

M a

nd

CM

cur

rent

s fl o

win

g en

tirel

y w

ithin

th

e V

SD

ass

embl

y, w

hich

incl

udes

an

y m

ains

cho

kes

or fi

lters

, and

any

ou

tput

fi lte

rs a

nd/o

r mot

or c

able

sc

reen

bon

ds (a

t the

cho

pper

end

). H

owev

er, e

lect

rical

inst

alle

rs o

ften

seem

to b

e of

the

opin

ion

that

all

earth

s or

gro

unds

are

equ

ival

ent,

and

also

that

it d

oes

not m

atte

r exa

ctly

w

here

the

vario

us c

ompo

nent

s

asso

ciat

ed w

ith a

VS

D a

re in

stal

led

([37]

reco

rds

som

e di

ffi cu

lties

with

th

is).

So,

in p

ract

ice,

the

elec

trica

l in

stal

latio

n of

a V

SD

and

/or i

ts

asso

ciat

ed c

ompo

nent

s (c

hoke

s,

fi lte

rs, i

sola

ting

trans

form

ers,

mot

or

cabl

e sc

reen

bon

ds, e

tc.)

mig

ht n

ot

be c

ompa

ct, a

nd it

s ea

rth/g

roun

d co

nduc

tors

may

con

nect

all

over

the

plac

e.

Figu

re 2

3:Ex

ampl

e of

a s

uita

ble

360°

bon

d fo

r sol

id c

ondu

it

Whe

re it

is d

iffi c

ult t

o so

urce

hig

h-cu

rren

t cab

les

with

goo

d qu

ality

sc

reen

s, o

r whe

n su

ppre

ssin

g th

e no

ise

from

a le

gacy

sys

tem

that

us

ed a

n un

scre

ened

mot

or c

able

, ov

erbr

aids

or s

hiel

ded

fl exi

ble

cond

uit

can

be u

sed,

as

show

n in

Fig

ure

22.

Whe

n ch

oosi

ng e

ither

, mak

e su

re th

at

appr

opria

te 3

60°

glan

ds o

r con

nect

ors

are

avai

labl

e fo

r it.

Sol

id c

ondu

it m

akes

the

best

scr

een

for a

mot

or c

able

, but

the

usua

l “b

anjo

” was

hers

are

use

less

for

supp

ress

ion

purp

oses

bec

ause

they

re

ly o

n le

ngth

s of

wire

to b

ond

them

to

an e

arth

/gro

und

term

inal

, and

so

have

to

o hi

gh a

n im

peda

nce

at R

F. F

igur

e 23

sho

ws

one

man

ufac

ture

r’s s

olut

ion

– a

cond

uit n

ut th

at m

akes

a m

ulti-

poin

t 360

° bo

nd b

etw

een

the

solid

co

ndui

t and

a m

etal

enc

losu

re a

t the

po

int o

f pen

etra

tion

of th

e en

clos

ure.

Figu

re 2

2:Ex

ampl

es o

f scr

eene

d fl e

xibl

e co

ndui

t and

ove

rbra

id

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3839

stru

ctur

e, u

sing

ver

y sh

ort

elec

tric

al b

onds

. Fol

low

all

the

nece

ssar

y sa

fety

cod

es ta

king

th

e ea

rth/

grou

nd le

akag

e cu

rren

t fro

m e

ach

into

acc

ount

(c

ould

be

seve

ral a

mps

, due

to

the

mai

ns fi

lterin

g).

4.4.

Mor

e de

tails

on

supp

ress

ing

PDS

emis

sion

sA

little

Gui

de li

ke th

is c

anno

t be

a te

xtbo

ok a

nd p

rovi

de e

very

thin

g on

e m

ight

nee

d to

kno

w, b

ut a

t lea

st it

can

pr

ovid

e th

e ba

sics

, and

this

has

bee

n do

ne a

bove

. Thi

s se

ctio

n pr

ovid

es

a fe

w a

dditi

onal

not

es, a

nd m

any

refe

renc

es, o

n su

ppre

ssin

g P

DS

em

issi

ons.

4.4.

1. O

btai

n m

anuf

actu

rer’s

EM

C in

stru

ctio

ns a

nd fo

llow

th

emV

FD a

nd V

SD

man

ufac

ture

rs E

MC

de

sign

/inst

alla

tion

guid

es s

houl

d al

way

s be

obt

aine

d, a

nd th

eir a

dvic

e fo

llow

ed a

ccur

atel

y. H

owev

er, t

hey

may

not

aim

to a

chie

ve th

e de

gree

of

nois

e su

ppre

ssio

n th

at is

nee

ded

(for

exam

ple

whe

n in

stal

ling

man

y P

DS

s in

one

sys

tem

, suc

h as

the

exam

ple

of

Figu

re 3

).

Ther

e ar

e m

any

gene

ral g

uide

s an

d te

xtbo

oks

on s

uppr

essi

ng e

mis

sion

s fro

m m

otor

driv

es, i

nclu

ding

[31]

, [32

], [3

3], [

34],

[35]

and

[36]

, and

thes

e m

ight

pro

vide

suf

fi cie

nt in

form

atio

n to

ove

rcom

e an

y sh

ortc

omin

gs in

the

driv

e m

anuf

actu

rer’s

EM

C in

stal

latio

n in

stru

ctio

ns. I

f eve

n m

ore

info

rmat

ion

is re

quire

d, s

ee th

e fo

llow

ing

subs

ectio

ns.

It is

how

ever

ver

y im

porta

nt in

deed

th

at th

e fo

llow

ing

two

gene

ral

inst

alla

tion

rule

s ar

e fo

llow

ed:

a) A

ll of

the

com

pone

nt p

arts

of

a VS

D, p

lus

its a

ssoc

iate

d su

ppre

ssio

n co

mpo

nent

s (c

hoke

s, fi

lters

, iso

latin

g tr

ansf

orm

ers,

mot

or c

able

sc

reen

bon

ds, e

tc.)

mus

t be

in

very

clo

se p

roxi

mity

, ide

ally

al

l con

tain

ed w

ithin

one

met

al

encl

osur

e.

b) A

ll of

the

eart

h/gr

ound

co

nduc

tors

ass

ocia

ted

with

th

e co

mpo

nent

par

ts in

a)

abov

e m

ust c

onne

ct to

one

po

int,

idea

lly th

e ch

assi

s,

fram

e, b

ackp

late

or s

urfa

ce

of th

e m

etal

cab

inet

they

are

al

l con

tain

ed w

ithin

. Th

is o

ne

poin

t mus

t the

n co

nnec

t to

the

site

’s o

r ves

sel’s

saf

ety

eart

h/gr

ound

str

uctu

re v

ia o

ne

cond

ucto

r – fo

llow

ing

all t

he

nece

ssar

y sa

fety

cod

es ta

king

th

e ea

rth/

grou

nd le

akag

e cu

rren

t int

o ac

coun

t (it

coul

d be

sev

eral

am

ps, d

ue to

the

mai

ns fi

lterin

g).

I mak

e no

apo

logy

for r

epea

ting

som

e of

the

poin

ts a

lread

y em

phas

ised

in

the

earli

er te

xt. E

lect

rical

inst

alle

rs

mus

t be

cont

rolle

d ve

ry c

aref

ully

to

ensu

re th

at th

ese

rule

s ar

e m

et in

fu

ll –

othe

rwis

e al

l the

tim

e an

d co

st

of d

eter

min

ing

how

to s

uppr

ess

the

driv

es w

ill b

e w

aste

d, a

nd th

e E

MC

engi

neer

s in

volv

ed w

ill b

e bl

amed

for

getti

ng it

wro

ng, w

hen

the

prob

lem

is

inco

rrec

t ins

talla

tion.

I stro

ngly

reco

mm

end

to a

ll E

MC

en

gine

ers

asso

ciat

ed w

ith s

uch

proj

ects

, tha

t the

y w

rite

dow

n m

anda

tory

requ

irem

ents

for t

he

inst

alla

tion

of th

eir s

uppr

essi

on

devi

ces,

usi

ng a

s m

uch

deta

il as

ne

eded

to c

omm

unic

ate

with

the

elec

trica

l ins

talle

rs in

term

s th

at th

ey

will

cle

arly

und

erst

and

– an

d in

sist

ing

that

the

cont

ract

with

the

cust

omer

in

clud

es a

n ite

m c

over

ing

thei

r in

spec

tion

and

appr

oval

of t

he fi

nal

elec

trica

l ins

talla

tion.

Som

e re

ader

s m

ight

con

trast

poi

nt b

) ab

ove

with

oth

er R

EO

Gui

des,

boo

ks

and

artic

les

I hav

e w

ritte

n (e

.g. [

19]

[26]

) in

whi

ch th

e vi

rtues

of m

eshe

d co

mm

on-b

ondi

ng n

etw

orks

(ME

SH

-C

BN

s) a

re e

xtol

led

at le

ngth

. Not

e th

at th

ese

also

allo

w th

e po

ssib

ility

of

com

bini

ng s

ingl

e-po

int b

onde

d sy

stem

s w

ith m

esh-

bond

ed o

nes,

so

ther

e is

no

confl

ict.

How

ever

, if a

M

ES

H-C

BN

or M

ES

H-IB

N (s

ee [1

9] o

r [2

6] fo

r defi

niti

ons)

that

can

con

trol u

p to

30M

Hz,

at l

east

, exi

sts

in th

e ar

ea

whe

re th

e V

SD

and

its

supp

ress

ion

com

pone

nts

are

loca

ted,

then

b) c

an

be m

odifi

ed to

read

as

follo

ws:

b*) A

ll of

the

eart

h/gr

ound

co

nduc

tors

ass

ocia

ted

with

th

e co

mpo

nent

par

ts in

a)

abov

e m

ust c

onne

ct to

thei

r lo

cal m

eshe

d C

BN

or I

BN

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4041

phas

e C

M c

hoke

com

pone

nts

can

be

conn

ecte

d in

ser

ies.

Whe

n try

ing

to s

peci

fy y

our o

wn

mai

ns fi

lter i

n th

e ab

senc

e of

gui

danc

e fro

m th

e dr

ive

man

ufac

ture

r (or

whe

n th

at in

form

atio

n pr

oves

inad

equa

te)

it is

impo

rtant

to u

nder

stan

d th

at,

in re

al li

fe, m

ains

fi lte

rs o

pera

te

with

“mis

mat

ched

” inp

ut a

nd o

utpu

t im

peda

nces

– i.

e. th

ey a

re n

ot b

oth

50Ω

, or e

ven

both

the

sam

e. A

ll m

ains

fi lte

rs re

sona

te a

nd p

rovi

de

gain

rath

er th

an a

ttenu

atio

n at

thei

r re

sona

nt fr

eque

ncie

s, a

nd e

spec

ially

so

whe

n op

erat

ed m

ism

atch

ed

– as

they

alw

ays

are

in re

al-li

fe. B

ut

atte

nuat

ion

data

from

mos

t dis

tribu

ters

an

d so

me

man

ufac

ture

rs d

o no

t sho

w

this

, bec

ause

they

onl

y sh

ow th

e re

sults

of “

mat

ched

” tes

ts (i

.e. 5

inpu

t and

out

put).

How

to d

eal w

ith th

e pr

oble

ms

of fi

lter

reso

nanc

e is

dis

cuss

ed in

det

ail i

n se

ctio

n 5.

10.1

of [

19],

4.7.

1 of

[20]

an

d C

hapt

er 8

.1.3

.1 o

f [26

]. Th

ese

all b

asic

ally

reco

mm

end

getti

ng

all t

he C

M a

nd D

M, m

atch

ed a

nd

mis

mat

ched

test

dat

a fro

m th

e fi l

ter

supp

lier (

6 cu

rves

in a

ll), d

raw

ing

the

wor

st c

ase

of a

ll of

the

atte

nuat

ion

curv

es, a

nd a

ssum

ing

that

a fi

lter’s

re

al-li

fe p

erfo

rman

ce w

ill b

e no

bet

ter

than

that

.

Cas

cadi

ng m

ains

fi lte

rs is

gen

eral

ly

a ba

d id

ea. R

eson

ance

s ca

n oc

cur

that

mak

e th

e at

tenu

atio

n of

the

com

bina

tion

wor

se th

an a

ny o

f the

fi lte

rs o

n th

eir o

wn,

so

grea

t car

e sh

ould

be

take

n w

hen

a V

FD is

fi tte

d w

ith a

n in

tern

al m

ains

fi lte

r, bu

t its

pe

rform

ance

is n

ot e

noug

h an

d yo

u ar

e te

mpt

ed to

add

ano

ther

fi lte

r in

serie

s w

ith it

.

How

ever

, mul

ti-st

age

fi lte

rs a

re

avai

labl

e th

at h

ave

exce

llent

pe

rform

ance

, alth

ough

the

mor

e st

ages

they

hav

e, th

e la

rger

, hea

vier

an

d m

ore

cost

ly th

ey te

nd to

be.

But

th

e au

thor

kno

ws

cust

om-e

ngin

eerin

g co

ntro

l cub

icle

man

ufac

ture

rs w

ho

auto

mat

ical

ly fi

t a 1

00A

3-ph

ase

5-st

age

mai

ns fi

lter t

o th

e in

com

ing

supp

ly o

f the

ir ca

bine

ts. A

lthou

gh

over

-spe

cifi e

d in

mos

t cas

es, t

hey

reck

on th

at it

sav

es th

em ti

me

and

cost

ove

rall,

by

avoi

ding

the

need

to

spe

nd ti

me

choo

sing

and

pro

ving

w

hich

is th

e m

ost c

ost-e

ffect

ive

fi lte

r fo

r eac

h ca

bine

t.

Mos

t sta

ndar

d m

ains

fi lte

rs s

old

as

‘EM

C fi

lters

’ will

not

pro

vide

muc

h at

tenu

atio

n fo

r the

VS

D’s

em

issi

ons

belo

w 1

50kH

z (s

ee th

e ca

se s

tudy

in

3.4)

. Filt

ers

suita

ble

for V

SD

s m

ust

prov

ide

good

atte

nuat

ion

dow

n to

the

chop

per’s

fund

amen

tal f

requ

ency

(i.e

. sw

itchi

ng fr

eque

ncy)

for b

oth

the

DM

an

d C

M n

oise

em

issi

ons.

The

CM

at

tenu

atio

n is

esp

ecia

lly im

porta

nt.

CM

+ D

M o

utpu

t fi lt

ers

conv

ert t

he

PW

M o

utpu

t int

o a

rela

tivel

y “c

lean

” D

C o

r AC

wav

efor

m, t

hat c

an b

e se

nt

sign

ifi ca

nt d

ista

nces

, ove

r per

fect

ly

ordi

nary

cab

les

to th

e m

otor

, with

out

4.4.

2. F

ilter

ing

The

spec

ifi ca

tions

for t

he fi

lters

sh

ould

be

obta

ined

from

the

VFD

or

VS

D m

anuf

actu

rer’s

det

aile

d E

MC

in

stru

ctio

ns fo

r exa

ctly

the

mod

el o

f dr

ive

bein

g us

ed. W

hen

not u

sing

an

outp

ut fi

lter,

long

er m

otor

cab

les

– or

sc

reen

ed o

r arm

oure

d m

otor

cab

les

– w

ill h

ave

mor

e st

ray

capa

cita

nce,

ca

usin

g an

incr

ease

in th

e m

agni

tude

of

the

chop

per’s

CM

cur

rent

s, a

nd

may

ther

efor

e ne

ed to

use

hig

her-

spec

ifi ca

tion

mai

ns fi

lters

for t

he s

ame

leve

l of e

mis

sion

s (a

ll el

se b

eing

the

sam

e).

So

the

mai

ns fi

lter s

peci

fi cat

ions

in a

pr

oper

ly d

ocum

ente

d E

MC

inst

alla

tion

guid

e sh

ould

sho

w h

ow th

e fi l

ter

spec

ifi ca

tions

dep

end

on th

e le

ngth

of

the

mot

or c

able

, and

in s

ome

case

s on

the

type

of c

able

too

(e.g

. scr

eene

d ca

ble,

or c

able

rout

ed in

con

duit,

will

ha

ve h

ighe

r stra

y ca

paci

tanc

e th

an

the

sam

e le

ngth

of u

nscr

eene

d).

For m

ore

info

rmat

ion

on E

MC

fi lte

ring,

an

d ho

w to

ass

embl

e it

in c

abin

ets,

sy

stem

s an

d in

stal

latio

ns to

get

max

i-m

um b

enefi

ts, s

ee s

ectio

n 5.

10 o

f [1

9], 4

.7 o

f [20

] and

Cha

pter

8 o

f [26

].

Mai

ns h

arm

onic

s ca

n be

fi lte

red,

in

stea

d of

sim

ply

redu

ced

by li

ne

indu

ctor

s. H

owev

er, b

ecau

se o

f the

ir lo

w fr

eque

ncie

s sp

ecia

l pas

sive

and

/or

act

ive

fi lte

ring

tech

niqu

es a

re u

sed,

an

d th

ese

are

disc

usse

d in

pag

es 5

1 th

roug

h 55

of [

29].

Whe

re R

F in

terfe

renc

e is

sus

pect

ed

from

a m

ains

or o

utpu

t cab

le, i

t will

us

ually

be

the

CM

cur

rent

s th

at a

re

to b

lam

e. C

lam

ping

a fe

rrite

toro

id

arou

nd a

ll of

the

phas

e an

d ne

utra

l co

nduc

tors

in th

e ca

ble

or b

undl

e, w

ith

or w

ithou

t inc

ludi

ng th

eir a

ssoc

iate

d pr

otec

tive

earth

ing

(saf

ety

grou

ndin

g)

cond

ucto

r, ca

n so

met

imes

be

enou

gh

to s

top

the

inte

rfere

nce,

and

is

espe

cial

ly e

ffect

ive

at fr

eque

ncie

s ab

ove

30M

Hz.

At f

requ

enci

es b

elow

30

MH

z tw

o or

mor

e fe

rrite

toro

ids

may

be

nee

ded

in s

erie

s on

the

cabl

e.

Dis

tribu

tors

sto

ck m

any

suita

ble

ferr

ite to

roid

s, a

nd th

e sp

lit v

ersi

ons

are

bette

r for

retro

fi ttin

g (a

ll E

MC

en

gine

ers

carr

y m

any

kilo

gram

s of

va

rious

type

s of

ferr

ite w

hen

visi

ting

a si

te to

try

to s

olve

a p

robl

em).

It is

impo

rtant

to e

nsur

e th

at a

ll of

th

e po

wer

con

duct

ors

asso

ciat

ed

with

a m

ains

sup

ply

or m

otor

load

pa

ss th

roug

h th

e fe

rrite

toro

id, a

nd

it m

ay b

e ne

cess

ary

to w

ind

thos

e co

nduc

tors

two

or e

ven

thre

e tim

es o

n th

e to

roid

. Alw

ays

chec

k th

at –

whe

n in

stal

led

on a

cab

le –

the

ferr

ites

do

not g

et to

o ho

t to

hold

you

r han

d on

fo

r sev

eral

min

utes

, whe

n th

e dr

ive

is ru

nnin

g at

full

pow

er. I

deal

ly, th

ey

wou

ld h

ardl

y ge

t war

m a

t all,

and

if

they

do

it us

ually

mea

ns th

at a

muc

h la

rger

ferr

ite is

requ

ired.

For e

ven

bette

r per

form

ance

from

a

ferr

ite C

M fi

lter a

t low

freq

uenc

ies,

w

ound

sin

gle-

phas

e an

d th

ree-

Page 25: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

4243

Shi

ps a

nd o

ther

ves

sels

gen

eral

ly

use

mai

ns s

uppl

ies

that

do

not h

ave

thei

r neu

tral d

irect

ly b

onde

d to

thei

r ea

rth/g

roun

d st

ruct

ure

[35]

, and

som

e la

nd-b

ased

inst

alla

tions

als

o us

e th

is

prac

tice.

Thi

s si

tuat

ion

is d

iscu

ssed

in

Sec

tion

4.5.

4.4.

3. S

afet

y is

sues

with

fi l

terin

gFi

lters

con

tain

cap

acito

rs fr

om th

e ph

ase

cond

ucto

rs (m

ains

or m

otor

) to

the

earth

/gro

und,

and

thes

e in

crea

se th

e cu

rren

t in

the

prot

ectiv

e ea

rthin

g co

nduc

tor (

the

gree

n/ye

llow

st

riped

wire

in th

e m

ains

sup

ply)

. S

afet

y st

anda

rds

and

elec

trica

l w

iring

cod

es s

et q

uite

low

lim

its o

n th

is c

urre

nt, t

o he

lp p

reve

nt e

lect

ric

shoc

k ha

zard

s, b

ut th

ey w

ill a

llow

an

y am

ount

of e

arth

/gro

und

leak

age

curr

ent w

hen

high

-inte

grity

ear

thin

g/gr

ound

ing

syst

ems

are

used

with

a

fi xed

VS

D in

stal

latio

n (i.

e. o

ne th

at

does

not

hav

e a

fl exi

ble

mai

ns le

ad o

r m

ains

plu

g, s

omet

imes

cal

led

“non

-pl

ugga

ble”

equ

ipm

ent.)

.

The

high

ear

th/g

roun

d le

akag

e cu

rren

ts c

ause

d by

fi lte

rs c

an a

lso

mak

e it

impo

ssib

le to

use

resi

dual

-cu

rren

t circ

uit b

reak

ers

(RC

CB

s),

earth

leak

age

circ

uit b

reak

ers

(ELC

Bs)

or g

roun

d-fa

ult i

nter

rupt

ers

(GFI

s).

Whe

re th

e m

ains

sys

tem

is is

olat

ed

from

the

safe

ty e

arth

/gro

und

(see

4.5

),

or w

hen

it is

“cor

ner-

grou

nded

” (on

e ph

ase

conn

ecte

d to

ear

th/g

roun

d,

rath

er th

an th

e ne

utra

l), a

ll ca

paci

tors

co

nnec

ted

to th

e ea

rth/g

roun

d (e

.g.

in a

fi lte

r) s

houl

d be

saf

ety-

rate

d fo

r th

e fu

ll ph

ase-

to-p

hase

vol

tage

, rat

her

than

pha

se-to

-neu

tral.

4.4.

4. B

enefi

ts o

f iso

latin

g tr

ansf

orm

ers

Whe

re a

BD

M is

not

pow

ered

from

a

co-lo

cate

d de

dica

ted

step

-dow

n is

olat

ing

mai

ns tr

ansf

orm

er, a

nd

whe

re th

e m

ains

pow

er s

uppl

y th

at

feed

s it

is s

hare

d w

ith o

ther

ele

ctro

nic

equi

pmen

t (w

hich

may

incl

ude

othe

r B

DM

s) th

at a

re n

ot c

o-lo

cate

d w

ith

the

BD

M c

once

rned

– th

en a

num

ber

of E

MC

issu

es a

rise

that

may

be

best

dea

lt w

ith b

y fi t

ting

the

BD

M

with

a d

edic

ated

co-

loca

ted

isol

atin

g tra

nsfo

rmer

.

Isol

atin

g tra

nsfo

rmer

s ar

e la

rge

and

cost

ly c

ompo

nent

s, e

spec

ially

for

high

-pow

er B

DM

s, b

ut o

mitt

ing

them

or

tryi

ng to

use

less

cos

tly a

ltern

ativ

es

can

prov

e to

be

mor

e co

stly

ove

rall

(see

sec

tion

3).

In s

ituat

ions

whe

re a

mai

ns p

ower

su

pply

feed

s tw

o or

mor

e ite

ms

of

equi

pmen

t spr

ead

over

a s

ite o

r ve

ssel

, the

DM

impe

danc

es o

f the

ph

ases

can

bec

ome

diffe

rent

from

ea

ch o

ther

due

to u

nequ

al lo

adin

g,

and

the

CM

impe

danc

e be

twee

n th

e ph

ases

and

the

earth

/gro

und

can

caus

ing

inte

rfere

nce

prob

lem

s –

inci

dent

ally

impr

ovin

g ca

ble

and

mot

or

life

as m

entio

ned

earli

er. B

ut b

ecau

se

they

are

cos

tly, s

uch

outp

ut fi

lters

w

ill p

roba

bly

not e

ven

be m

entio

ned

in m

ost d

rive

man

ufac

ture

rs’ E

MC

in

stru

ctio

ns.

Whe

re u

sing

scr

eene

d m

otor

cab

les

is im

prac

tical

for s

ome

reas

on,

CM

+, D

M fi

lters

like

RE

O’s

Sin

us +

+ se

ries

may

be

the

only

sol

utio

n. T

he

man

ufac

ture

rs o

f the

fi lte

rs s

houl

d be

able

to te

ll yo

u w

hich

VFD

s or

VS

Ds

they

are

sui

tabl

e fo

r.

In b

etw

een

low

-cos

t fer

rite

toro

ids

and

expe

nsiv

e C

M +

DM

mot

or o

utpu

t fi l

ters

, the

re a

re v

ario

us m

ediu

m-c

ost

alte

rnat

ives

. So-

calle

d dV

/dt fi

lter

s “r

ound

off”

the

edge

s of

the

mot

or

outp

ut P

WM

wav

efor

ms,

whi

ch –

in

the

frequ

ency

dom

ain

– at

tenu

ates

th

e hi

gher

freq

uenc

y no

ise

spec

trum

. Fi

gure

24

show

s th

e ef

fect

of a

pply

ing

a R

EO

dV

/dt o

utpu

t fi lt

er to

a V

FD.

Ris

ing

edge

of P

WM

out

put

wav

efor

m fr

om a

VFD

The

sam

e VF

D o

utpu

tw

avef

orm

with

a R

EO

CN

W 8

11 “d

V/dt

filte

r” fit

ted

Figu

re 2

4:“R

ound

ing

off”

the

PWM

wav

efor

m w

ith a

dV/

dt fi

lter

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4445

Ant

i-vib

ratio

n de

vice

,e.

g. A

nti-v

ibra

tion

was

her

or o

ther

met

hod

But

nev

er u

se c

hem

ical

‘thre

ad-lo

ck’

Not

e: th

is R

F-bo

ndis

sho

wn

parti

ally

disa

ssem

bled

Met

al c

ompo

nent

s to

be R

F-bo

nded

Rel

iabl

e R

F-bo

nds

re c

reat

ed b

y pr

essi

ngto

geth

er h

ighl

y-co

nduc

tive

met

al s

urfa

ces

Mat

eria

ls s

houl

d be

cho

sen

to p

reve

ntox

idat

ion

or c

orro

sion

ove

r the

life

cycl

e,ta

king

the

real

-life

env

ironm

ent i

nto

acco

unt

Any

insu

latin

g fin

ishe

sre

mov

ed fr

om e

ntire

bond

ing

area

(e.g

. pai

nt, a

nodi

sing

,po

lym

er p

assi

vatio

n)

Con

duct

ive

gask

ets

coul

d be

inse

rted

here

Do

not r

ely

on s

crew

thre

ads

of a

ny ty

pe to

mak

e th

e R

F-bo

nds

Figu

re 2

5: R

F-bo

ndin

g tw

o m

etal

sur

face

s

beco

me

quite

low

due

to th

e st

ray

capa

cita

nces

of t

he lo

ng c

able

s an

d th

e C

M fi

lters

in o

ther

equ

ipm

ent.

Thes

e im

peda

nce

effe

cts

nega

tivel

y af

fect

the

perfo

rman

ce o

f a B

DM

’s

mai

ns fi

lter (

see

[36]

). Fi

tting

an

isol

atin

g tra

nsfo

rmer

rest

ores

the

bala

nce

to th

e D

M im

peda

nces

, and

al

so re

stor

es a

hig

h C

M im

peda

nce,

he

lpin

g th

e m

ains

fi lte

r ach

ieve

its

desi

gned

pot

entia

l.

Ear

lier,

I dis

cuss

ed h

ow a

BD

M’s

C

M re

turn

cur

rent

s w

ere

‘ste

ered

’ by

capa

cito

rs in

its

inpu

t and

/or o

utpu

t fi l

ters

and

thei

r low

-impe

danc

e bo

ndin

g to

the

BD

M’s

cha

ssis

/fram

e,

so th

at th

ey fl

owed

mos

tly in

the

BD

M’s

ass

embl

y. B

ut w

hen

the

CM

im

peda

nce

of th

e m

ains

sup

ply

is lo

w th

e ra

tio b

etw

een

the

path

im

peda

nces

pro

vide

d by

the

mai

ns

fi lte

r and

that

pro

vide

d by

the

mai

ns

supp

ly m

ight

not

be

as h

igh

as w

e w

ould

like

. For

exa

mpl

e, w

here

ther

e ar

e tw

o or

mor

e eq

uipm

ents

fi tte

d w

ith

mai

ns fi

lters

con

nect

ed to

a m

ains

su

pply,

thei

r low

CM

impe

danc

es

enco

urag

e th

e C

M c

urre

nts

of e

ach

item

of e

quip

men

t to

fl ow

in th

e ot

her’s

mai

ns fi

lter –

enc

oura

ging

CM

cu

rren

ts to

fl ow

wid

ely,

whi

ch is

not

w

hat w

e w

ant.

Whe

re a

BD

M’s

mai

ns fi

lter d

oes

not

incl

ude

a C

M c

hoke

on

the

supp

ly

side

of i

ts C

M c

apac

itors

, thi

s pr

oble

m

can

be re

duce

d by

fi tti

ng a

CM

cho

ke

in th

at p

ositi

on, c

o-lo

cate

d w

ith th

e

mai

ns fi

lter.

But

all

chok

es c

ause

so

me

volta

ge d

rop

and

so th

is m

ight

ca

use

an in

crea

sed

rate

of t

rippi

ng

due

to s

ags

or d

ips

in th

e su

pply.

A

noth

er p

ossi

bilit

y is

to fi

t an

earth

/gr

ound

cho

ke to

the

BD

M, w

hich

of

cour

se w

ill o

nly

wor

k if

it is

fi tte

d to

th

e si

ngle

con

duct

or th

at c

onne

cts

the

BD

M’s

ear

th/g

roun

d to

the

earth

/gr

ound

stru

ctur

e of

the

site

or v

esse

l (s

ee it

em b

in S

ectio

n 4.

3).

But

an

isol

atin

g tra

nsfo

rmer

ded

icat

ed

to th

e B

DM

and

co-

loca

ted

with

it

(see

item

a in

sec

tion

4.3)

will

pro

vide

m

uch

bette

r con

trol o

f CM

cur

rent

s th

an a

ny c

hoke

s.

A m

ains

isol

atin

g tra

nsfo

rmer

mig

ht

also

pro

ve to

be

suffi

cien

t, on

its

own

with

out a

mai

ns fi

lter,

for p

reve

ntin

g th

e C

M n

oise

from

a B

DM

’s m

ains

in

put f

rom

circ

ulat

ing

wid

ely.

It w

ould

do

littl

e or

not

hing

for t

he B

DM

’s D

M

nois

e em

issi

ons,

or t

he re

sulti

ng

wav

efor

m d

isto

rtion

, but

this

is o

ften

not a

s m

uch

of a

pro

blem

as

the

CM

no

ise

emis

sion

s an

yway

.

Whe

re a

BD

M is

fi tte

d w

ith a

mai

ns

fi lte

r tha

t dea

ls w

ith C

M n

oise

as

wel

l as

DM

, the

maj

ority

of p

robl

ems

with

wid

ely-

circ

ulat

ing

CM

cur

rent

s oc

cur a

t low

er fr

eque

ncie

s, b

elow

15

0kH

z. In

this

cas

e ex

perie

nce

seem

s to

sho

w th

at th

e no

rmal

ty

pe o

f con

stru

ctio

n fo

r an

isol

atin

g tra

nsfo

rmer

is a

dequ

ate

for c

ontro

lling

C

M c

urre

nts

in th

is fr

eque

ncy

rang

e.

How

ever

, the

re a

re te

chni

ques

av

aila

ble

for d

ecre

asin

g th

e st

ray

prim

ary-

seco

ndar

y in

terw

indi

ng

capa

cita

nce,

and

for a

ddin

g in

terw

indi

ng s

cree

ns. T

hese

can

be

use

d to

pro

vide

bet

ter i

sola

tion

perfo

rman

ce a

nd h

ighe

r CM

sou

rce

impe

danc

e, fr

om D

C to

radi

o fre

quen

cies

, whi

ch m

ay b

e ne

eded

on

occa

sion

, for

exa

mpl

e w

hen

a m

ains

fi l

ter i

s no

t fi tt

ed a

t all.

4.4.

5. M

ore

deta

il on

RF-

bond

ing

tech

niqu

esFi

gure

25

show

s th

e ba

sics

of t

he

idea

l met

hod

of R

F-bo

ndin

g tw

o m

etal

item

s to

geth

er (e

.g. R

F-bo

ndin

g th

e m

etal

bod

ies

of th

e m

ains

fi lte

r, re

ctifi

er a

nd c

hopp

er to

the

back

plat

e in

Fig

ure

16).

But

ther

e ar

e m

any

mor

e de

tails

th

at c

ould

be

impo

rtant

, and

in

som

e ca

ses

alte

rnat

ives

mig

ht b

e ap

prop

riate

, so

the

info

rmat

ion

in

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4647

4.4.

7. S

cree

ned

(shi

elde

d)

encl

osur

esE

N/IE

C 6

1800

-3 is

rath

er d

ism

issi

ve

of th

e po

tent

ial o

f PD

Ss

to in

terfe

re

with

radi

o re

cept

ion

thro

ugh

radi

ated

em

issi

ons.

How

ever

, VFD

s –

espe

cial

ly lo

w-p

ower

one

s sw

itchi

ng

at o

ver 2

0kH

z –

have

bee

n kn

own

to

inte

rfere

with

radi

ocom

mun

icat

ions

, as

som

e ite

ms

in [1

5] s

how

(e.g

. No.

24

).

As

long

ago

as

the

early

199

0s I

have

had

to im

prov

e th

e sh

ield

ing

of in

dust

rial c

ontro

l cab

inet

s th

at

cont

aine

d se

vera

l VFD

s, to

pas

s th

e ra

diat

ed e

mis

sion

test

s to

the

gene

ric

emis

sion

s st

anda

rd fo

r the

indu

stria

l en

viro

nmen

t (w

hich

was

EN

500

82-1

,

but i

s no

w E

N/IE

C 6

1000

-6-4

). E

ach

VFD

com

plie

d on

its

own,

but

whe

n al

l th

e dr

ives

in th

e ca

bine

t wer

e ru

nnin

g,

thei

r agg

rega

te e

mis

sion

s w

ere

sign

ifi ca

ntly

abo

ve th

e lim

it lin

e.

As

Pow

erFE

Ts a

nd IG

BTs

dev

elop

, th

ey a

re d

esig

ned

to s

witc

h fa

ster

to

redu

ce h

eat l

osse

s an

d in

crea

se

effi c

ienc

y, s

o th

e pr

ospe

cts

for

radi

ated

inte

rfere

nce

can

only

wor

sen.

A

nd a

s m

entio

ned

in s

ectio

n 3,

mor

e ra

dioc

omm

unic

atio

ns a

re b

eing

use

d ev

eryw

here

, whi

ch a

lso

incr

ease

s th

e po

tent

ial f

or ra

diat

ed in

terfe

renc

e fro

m

PD

Ss.

Des

igni

ng a

nd/o

r ins

talli

ng s

hiel

ded

encl

osur

es re

quire

s a

lot o

f atte

ntio

n to

det

ail,

but t

he b

asic

prin

cipl

es a

re

outli

ned

in F

igur

e 27

, whi

ch s

how

s

Cho

pper

Scr

eene

d B

DM

enc

losu

reM

otor

Scr

eene

d ca

bles

mus

tha

ve 3

60O R

F-bo

ndin

gco

nnec

tors

or g

land

sat

bot

h en

ds

Uns

hiel

ded

cabl

esm

ust a

ll be

filte

red

byth

roug

h-bu

lkhe

ad fi

lters

All

cabl

esro

uted

clo

seto

the

PE

C

Filte

rs

The

Par

alle

l Ear

th C

ondu

ctor

‘PE

C’ (

e.g.

a c

able

tray

)

Figu

re 2

7:Th

e ba

sic

prin

cipl

es o

f em

ploy

ing

a sc

reen

ed e

nclo

sure

Two

strip

s of

sof

t con

duct

ive

gask

et c

reat

e 36

0O

RF-

bond

s be

twee

n th

e ca

bles

’ scr

eens

and

the

high

ly-c

ondu

ctiv

e su

rface

of t

he c

hopp

er’s

met

alen

clos

ure,

cha

ssis

or f

ram

e - w

hen

the

clam

ping

plat

e is

tigh

tene

d do

wn.

Scr

eene

d ca

bles

ent

erin

g/le

avin

g th

e B

DM

(Stra

in re

lief a

nd e

nviro

nmen

tal s

ealin

g no

t sho

wn)

Met

al c

lam

ping

pla

teC

able

scr

eens

exp

osed

to m

ake

good

con

tact

with

the

gask

ets

Figu

re 2

6:A

low

-cos

t way

to R

F-bo

nd m

ultip

le c

able

scr

eens

sect

ion

5.7

of [1

9], 2

.2 th

roug

h 2.

5 of

[20]

and

Cha

pter

5 o

f [26

] may

be

usef

ul.

4.4.

6. M

ore

deta

il on

cab

le

scre

enin

g (s

hiel

ding

) te

chni

ques

This

will

be

foun

d in

sec

tions

5.7

.6

thro

ugh

5.7.

10 a

nd 5

.11

of [1

9], 3

.7 o

f [2

0] a

nd C

hapt

er 7

.2 o

f [26

].

Scr

een

bond

ing

need

not

be

cost

ly,

espe

cial

ly w

here

ther

e ar

e nu

mbe

r of

cab

les

scre

ens

to b

e bo

nded

(e.g

. to

a c

abin

et b

ackp

late

) as

show

n by

the

DIY

scr

een-

bond

ing

tech

niqu

e of

Fi

gure

26.

How

ever

, whe

re a

scr

eene

d en

clos

ure

(e.g

. cab

inet

, roo

m, e

tc.)

is u

sed

(see

4.

4.5)

, “pr

oper

” gla

nds

like

the

top

left-

hand

sid

e on

in F

igur

e 21

sho

uld

alw

ays

be u

sed

(or c

onne

ctor

s w

ith

sim

ilar s

cree

ned

brai

d te

rmin

atio

ns).

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4849

whi

nes

and

whi

stle

s if

rout

ed to

o cl

ose

to c

able

s as

soci

ated

with

a d

rive,

and

ar

e a

mat

ter o

f som

e co

ncer

n to

EN

/IE

C 6

1800

-3 (s

ee 6

.2.5

in [1

]). F

or a

re

al-li

fe e

xam

ple

of s

erio

us te

leph

one

inte

rfere

nce

from

a h

igh-

pow

er d

rive,

se

e Ite

m 1

in [1

5].

Cab

le c

lass

ifi ca

tion

and

segr

egat

ion

is c

over

ed in

sec

tion

4.8

of [1

9] (4

.4

is a

lso

impo

rtant

); 3.

3 of

[20]

and

C

hapt

er 7

.4 o

f [26

].

4.4.

9. C

omm

utat

ion

notc

hes

Volta

ge “n

otch

ing”

is a

n em

issi

on

prob

lem

cau

sed

by n

atur

ally

co

mm

utat

ed th

yris

tors

/tria

cs in

DC

dr

ives

. The

cro

ss-c

ondu

ctio

n w

hen

one

thyr

isto

r or t

riac

turn

s on

bef

ore

anot

her h

as fi

nish

ed tu

rnin

g of

f, m

omen

taril

y sh

orts

-out

thei

r pha

ses

caus

ing

a di

p w

ith a

dep

th o

f 100

%.

Alth

ough

this

is a

low

-freq

uenc

y no

ise,

it is

ver

y se

vere

and

can

in

terfe

re w

ith o

ther

equ

ipm

ent t

hat

is u

sing

thos

e ph

ases

. How

ever

, a

“3%

indu

ctor

” suc

h as

is o

ften

fi tte

d to

redu

ce e

mis

sion

s of

mai

ns

harm

onic

s an

d in

terh

arm

onic

s (s

ee

4.4.

8), w

ill g

ener

ally

pro

vide

ade

quat

e su

ppre

ssio

n.

[1] c

alls

this

ser

ies

indu

ctor

a

“dec

oupl

ing

reac

tanc

e” a

nd re

quire

s th

at it

s si

ze b

e sp

ecifi

ed.

4.4.

10.

Mai

ns h

arm

onic

s an

d in

terh

arm

onic

sTh

ese

are

typi

cally

sup

pres

sed

by

usin

g a

“3%

indu

ctor

” in

serie

s w

ith

the

rect

ifi er

, as

show

n in

Fig

ures

15

and

16. T

he 3

% re

fers

to th

e fa

ct th

at

whe

n ca

rryi

ng it

s fu

ll ra

ted

curr

ent,

its

inte

rnal

impe

danc

e re

duce

s th

e m

ains

vo

ltage

by

3%. T

his

is c

onsi

dere

d to

be

a co

st-e

ffect

ive

com

prom

ise,

bu

t som

etim

es it

is n

eces

sary

to g

o as

hig

h as

a 4

% in

duct

or. I

ncre

asin

g th

e im

peda

nce

even

furth

er is

not

ad

vise

d, s

o if

serie

s in

duct

ors

have

no

t man

aged

to re

duce

the

harm

onic

an

d in

terh

arm

onic

em

issi

ons

by

enou

gh, o

ther

tech

niqu

es m

ust b

e us

ed in

stea

d of

, or a

s w

ell a

s, s

erie

s in

duct

ors.

Sin

gle-

phas

e V

SD

s an

d V

FDs

suffe

r fro

m e

mitt

ing

all o

f the

odd

-nu

mbe

red

mai

ns h

arm

onic

s, in

clud

ing

tripl

ens

as m

entio

ned

earli

er.

On

four

wire

sys

tem

s (i.

e. 3

pha

se +

N)

the

tripl

ens

add

arith

met

ical

ly in

the

neut

ral c

ondu

ctor

cau

sing

sig

nifi c

ant

prob

lem

s w

ith lo

calis

ed p

ower

qua

lity

and

equi

pmen

t ope

ratio

n.

How

ever

, th

ree-

phas

e (6

pul

se) d

rives

runn

ing

from

reas

onab

ly lo

w-d

isto

rtion

mai

ns

supp

lies

have

ver

y lo

w le

vels

of

“trip

len”

har

mon

ics,

of w

hich

the

mos

t im

porta

nt a

re th

e 3rd

and

9th. L

osin

g th

e 3rd

mak

es it

eas

ier t

o us

e se

ries

indu

ctor

s to

get

goo

d le

vels

of m

ains

ha

rmon

ic re

duct

ion.

that

no

cond

ucto

r of a

ny ty

pe (e

ven

a m

echa

nica

l pus

h-ro

d or

met

al p

ipe)

ca

n en

ter/e

xit a

scr

eene

d en

clos

ure

with

out e

ither

:

a) B

eing

RF-

bond

ed to

the

encl

osur

e’s

met

al w

all a

t the

poi

nt o

f en

try/e

xit,

or

b) B

eing

fi lte

red

to a

n ap

prop

riate

sp

ecifi

catio

n, w

ith th

e fi l

ter R

F-bo

nded

to

the

encl

osur

e’s

met

al w

all a

t the

po

int o

f ent

ry/e

xit,

or

c) B

eing

a s

cree

ned

cabl

e w

ith a

n ap

prop

riate

spe

cifi c

atio

n, th

e sc

reen

be

ing

RF-

bond

ed (i

.e. 3

60°

bond

ed)

to th

e en

clos

ure’

s m

etal

wal

l at t

he

poin

t of e

ntry

/exi

t.

No

alte

rnat

ives

are

eve

r per

mitt

ed, f

or

any

reas

on. I

am

ofte

n as

ked

to s

olve

re

al-li

fe p

robl

ems

in w

hich

exp

ensi

ve

shie

lded

cab

inet

s ar

e fo

und

to b

e “le

akin

g”, a

nd th

e us

ual p

robl

em is

th

at s

ome

cond

ucto

r ass

umed

to

be in

sign

ifi ca

nt (e

.g. h

ydra

ulic

pip

e,

mou

se c

able

, etc

.) ha

s be

en a

llow

ed

to e

nter

/exi

t the

enc

losu

re w

ithou

t on

e of

the

abov

e th

ree

met

hods

bei

ng

appl

ied.

How

ever

, som

etim

es th

e pr

oble

m h

as

been

that

the

syst

em in

tegr

ator

has

si

mpl

y cu

t a la

rge

hole

in th

e w

all o

r do

or o

f the

scr

eene

d en

clos

ure,

to

mou

nt th

eir h

uman

-mac

hine

inte

rface

, de

stro

ying

the

scre

enin

g ef

fect

iven

ess

in th

e pr

oces

s.

A gr

eat d

eal o

f det

ail o

n th

e de

sign

and

inst

alla

tion

of s

hiel

ded

encl

osur

es, o

f all

size

s fro

m ju

st la

rge

enou

gh fo

r one

sm

all V

FD, u

p to

sc

reen

ing

an e

ntire

room

or e

ven

a bu

ildin

g, w

ill b

e fo

und

in th

e fo

llow

ing:

se

ctio

n 5.

12 o

f [19

], se

ctio

n 5

of [2

0]

and

Cha

pter

6 o

f [26

].

4.4.

8. O

ther

EM

C te

chni

ques

The

abov

e di

scus

sion

has

not

ad

dres

sed

all t

he E

MC

tech

niqu

es

that

will

pro

babl

y be

requ

ired,

for

whi

ch re

ad [3

1] [3

2] [3

3] [3

4] [3

6] a

nd

[19]

[20]

and

[26]

.

For e

xam

ple,

mos

t (if

not a

ll) V

FD

man

ufac

ture

r’s E

MC

inst

alla

tion

inst

ruct

ions

, as

wel

l as

[33]

[34]

and

[3

6] w

ill in

clud

e th

e re

quire

men

t to

clas

sify

the

cabl

es a

ssoc

iate

d w

ith

a P

DS

acc

ordi

ng to

som

e ru

les,

and

th

en to

rout

e th

ese

“cab

le c

lass

es”

sepa

rate

ly fr

om e

ach

othe

r, w

ith

certa

in m

inim

um s

paci

ngs

to b

e m

aint

aine

d be

twee

n ca

ble

clas

ses

whe

re th

ey a

re ro

uted

in p

aral

lel.

This

ack

now

ledg

es th

e fa

ct th

at n

o ca

ble

scre

ens

or fi

lters

are

per

fect

, so

it h

elps

to re

duce

the

cros

stal

k be

twee

n th

e ca

bles

, esp

ecia

lly fr

om

the

mot

or o

utpu

t to

the

mai

ns s

uppl

y or

con

trol c

able

s. It

als

o he

lps

ensu

re

low

cro

ssta

lk to

cab

les

that

are

not

as

soci

ated

with

the

driv

e, s

uch

as

tele

phon

e ca

bles

, whi

ch c

an s

uffe

r dr

amat

ical

ly fr

om a

udio

-freq

uenc

y

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5051

is re

ally

a c

hopp

er th

at is

con

trolle

d to

sou

rce

or s

ink

mai

ns c

urre

nts

in

antip

hase

to th

ose

that

are

cau

sing

pr

oble

ms,

and

– d

espi

te it

s na

me

– is

no

t a fi

lterin

g te

chni

que

at a

ll. P

assi

ve

and

activ

e ha

rmon

ic fi

lters

are

ofte

n us

ed w

here

it is

des

ired

to d

eal w

ith

the

harm

onic

s of

all

the

equi

pmen

t on

one

fl oo

r of a

bui

ldin

g, o

r eve

n an

en

tire

build

ing,

site

or v

esse

l, in

stea

d of

dea

ling

with

them

at t

he le

vel o

f in

divi

dual

item

s of

equ

ipm

ent.

Act

ive

fi lte

rs, i

ntro

duce

d so

me

10

year

s ag

o, a

re e

xpen

sive

but

wid

ely

used

. Th

ese

elec

troni

c ‘fi

lters

’ pro

vide

a

very

low

impe

danc

e so

urce

(<1%

) fo

r the

har

mon

ic c

urre

nts.

The

refo

re,

if ra

ted

corr

ectly

, the

load

(s) d

raw

the

harm

onic

cur

rent

s fro

m th

e ac

tive

fi lte

r whi

lst t

he s

ourc

e pr

ovid

es o

nly

the

fund

amen

tal c

urre

nt.

Dep

endi

ng

on th

e ty

pe, a

ctiv

e fi l

ters

can

redu

ce

harm

onic

em

issi

ons

to b

elow

5%

. A

ctiv

e fi l

ters

are

par

alle

l dev

ices

, an

d so

onl

y ne

ed to

be

rate

d fo

r the

ha

rmon

ic c

urre

nt.

The

othe

r typ

e of

har

mon

ic fi

lter

whi

ch is

ver

y po

pula

r is

wor

ldw

ide

the

pass

ive

“wid

e sp

ectru

m fi

lter”

. Th

ese

are

mul

ti-lim

bed

reac

tors

w

ound

on

a co

mm

on c

ore,

fi tte

d w

ith a

sm

all c

apac

itor b

ank

(not

like

tra

ditio

nal p

assi

ve fi

lters

). Th

ey a

re

conn

ecte

d in

ser

ies

with

the

load

(s)

and

– de

pend

ing

on m

anuf

actu

rer

– ca

n al

so re

duce

the

I thd t

o ar

ound

5%

. O

ne m

anuf

actu

rer s

uppl

ies

thes

e

fi lte

rs u

p to

alm

ost 3

,000

kW fo

r bot

h A

C a

nd D

C d

rives

. B

eing

pas

sive

an

d lin

ear,

they

do

not c

ause

EM

I em

issi

ons.

Cos

t-effe

ctiv

enes

s ca

lcul

atio

ns m

ay

show

that

it c

osts

less

to a

llow

all

the

PD

Ss

on a

site

or i

n a

vess

el to

em

it th

eir h

arm

onic

s, a

nd to

cle

an

them

up

with

a s

ingl

e fi l

ter (

pass

ive

or

activ

e) s

o th

at th

ey d

o no

t cau

se to

o m

uch

dist

ortio

n of

the

mai

ns v

olta

ge

wav

efor

m.

Thes

e an

d ot

her “

inst

alla

tion

leve

l” te

chni

ques

are

dis

cuss

ed in

pag

es

42-6

2 of

[29]

, and

[35]

.

4.4.

11.

Mai

ns v

olta

ge

fl uct

uatio

ns[1

] set

s lim

its fo

r the

gen

erat

ion

of

mai

ns v

olta

ge fl

uctu

atio

ns, f

or w

hich

th

ere

are

only

a fe

w in

stal

latio

n-le

vel m

itiga

tion

tech

niqu

es, s

uch

as

Dyn

amic

Vol

tage

Res

tore

rs (D

VR

s)

see

page

s 36

-49

of [3

0].

At t

he le

vel o

f the

mot

or d

rive,

the

maj

or b

enefi

t co

mes

from

usi

ng “s

oft-

star

ting”

, esp

ecia

lly fo

r AC

mot

ors

beca

use

they

can

dra

w v

ery

larg

e m

agne

tisin

g cu

rren

ts w

hen

switc

hed

Dire

ct-O

n-Li

ne (D

OL)

nea

r the

ze

ro-c

ross

ings

of t

he m

ains

vol

tage

. U

sing

VFD

s so

lves

this

pro

blem

au

tom

atic

ally.

Whe

re h

igh-

pow

ered

driv

es h

ave

a ra

pidl

y fl u

ctua

ting

load

, the

fl uc

tuat

ing

Pha

se-s

hifti

ng m

ains

tran

sfor

mer

s ca

n be

use

d to

cre

ate

six-

phas

e (o

ften

calle

d 12

-pul

se) r

ectifi

ers

, w

hich

has

the

effe

ct o

f cau

sing

the

5th

and

7th h

arm

onic

s to

be

subs

tant

ially

ca

ncel

led

out i

n th

e re

ctifi

er’s

circ

uits

, so

that

its

fi rst

sig

nifi c

ant m

ains

ha

rmon

ic is

the

13th. I

ncre

asin

g m

ultip

les

of th

ree

phas

es (o

r six

pu

lses

) atte

nuat

es e

ven

high

er-o

rder

ha

rmon

ics,

but

the

spec

ifi ca

tion

on

the

purit

y of

the

mai

ns s

uppl

y’s

sine

w

avef

orm

and

equ

ipm

ent a

nd p

hase

sh

ift tr

ansf

orm

er q

ualit

y (in

tern

al

imba

lanc

e to

lera

nce

leve

ls) m

ust

incr

ease

with

the

num

ber o

f pha

ses

for t

his

to b

e ef

fect

ive.

How

ever

, us

ing

larg

e or

mul

tiple

-pha

se-s

hift

trans

form

ers,

as

is ty

pica

l of o

il pr

oduc

tion

plat

form

s, c

an s

till r

educ

e th

is e

xces

sive

vol

tage

dis

torti

on,

espe

cial

ly a

t hig

her o

rder

whe

re th

ey

are

both

mos

t pro

blem

atic

and

diffi

cul

t to

trea

t.

Shi

ps a

nd o

ther

ves

sels

ofte

n ha

ve

very

dis

torte

d m

ains

sup

plie

s be

caus

e th

eir e

lect

ricity

gen

erat

ors

have

muc

h hi

gher

(abo

ut 3

tim

es) t

he s

ourc

e im

peda

nce

of a

land

lubb

er’s

HV

tra

nsfo

rmer

of t

he s

ame

VA ra

ting,

and

al

so b

ecau

se o

f the

incr

ease

d us

e of

po

wer

ful V

FDs

in “e

lect

ric th

rust

ers”

an

d ev

en e

lect

rical

pro

puls

ion.

For

th

is re

ason

, 6-p

hase

and

hig

her

(12-

puls

e an

d hi

gher

) rec

tifi e

rs a

re

ofte

n un

suita

ble

for s

hips

, bec

ause

th

ey re

ly o

n lo

w-d

isto

rtion

mai

ns fo

r th

eir h

arm

onic

impr

ovem

ents

. So

ship

s an

d ve

ssel

s of

ten

use

spec

ial

harm

onic

sup

pres

sion

tech

niqu

es th

at

are

not c

omm

only

use

d in

land

-bas

ed

inst

alla

tions

, see

[35]

for d

etai

ls.

A re

ason

ably

new

des

ign

tech

niqu

e,

at th

e tim

e of

writ

ing,

is th

e “a

ctiv

e fro

nt e

nd” (

AFE

), w

hich

use

s IG

BTs

in

stea

d of

pla

in o

ld re

ctifi

ers.

The

se

are

switc

hed

at a

hig

h ra

te, j

ust l

ike

a ch

oppe

r tha

t driv

es P

WM

into

a

mot

or, b

ut c

ontro

l sof

twar

e ar

rang

es

the

sequ

enci

ng a

nd ti

min

g so

that

, af

ter p

assi

ng th

roug

h a

serie

s in

duct

or

to a

vera

ge o

ut th

e P

WM

, the

resu

lt is

a

rect

ifi er

that

app

ears

to th

e m

ains

su

pply

as

a su

bsta

ntia

lly li

near

(i.e

. re

sist

ive)

load

, whi

ch a

s a

dire

ct

cons

eque

nce

is c

laim

ed to

ach

ieve

lo

w e

mis

sion

s of

mai

ns h

arm

onic

s (<

5% I th

d).

How

ever

, AFE

s ac

hiev

e th

is a

t the

co

st o

f sig

nifi c

ant h

arm

onic

cur

rent

s in

the

supp

ly a

t the

sw

itchi

ng

frequ

ency

of t

he A

FE b

ridge

, hig

her

EM

I em

issi

ons

betw

een

10kH

z an

d 10

0kH

z, a

nd o

ther

a n

umbe

r of o

ther

is

sues

. A

FE re

ctifi

ers,

bei

ng s

erie

s de

vice

s, h

ave

to b

e di

men

sion

ed

for t

he to

tal l

oad.

Thi

s, o

f cou

rse,

is

a m

atte

r of d

rive

sele

ctio

n, a

nd is

no

t oth

erw

ise

unde

r the

con

trol o

f a

syst

em in

tegr

ator

or i

nsta

ller.

Filte

ring

was

men

tione

d ea

rlier

as

a m

eans

of s

uppr

essi

ng m

ains

ha

rmon

ics,

usi

ng p

assi

ve fi

lters

suc

h as

reso

nant

trap

s. A

noth

er te

chni

que

is th

e so

-cal

led

“act

ive

fi lte

r”, w

hich

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5253

nece

ssar

y) e

ither

fi lte

red

or s

cree

ned.

W

hen

fi lte

ring

tech

niqu

es a

re u

sed,

fi l

ters

may

be

need

ed a

t bot

h en

ds,

beca

use

the

DC

-Lin

k ca

rrie

s no

ises

ge

nera

ted

by b

oth

the

rect

ifi er

and

the

chop

per.

4.4.

14.

Neu

tral

shi

ft ca

n st

ress

mot

or in

sula

tion

Sec

tion

4-12

of [

36] d

iscu

sses

the

prob

lem

s of

incr

easi

ng n

eutra

l-ea

rth/g

roun

d vo

ltage

cau

sed

by

VS

Ds

with

Wye

-con

nect

ed in

puts

. It

also

dis

cuss

es s

olut

ions

that

can

be

used

whe

n a

Del

ta c

onne

cted

mai

ns

inpu

t can

not b

e us

ed. T

hese

incl

ude

usin

g an

isol

atio

n tra

nsfo

rmer

at t

he

mai

ns in

put a

nd fl

oatin

g th

e ne

utra

l co

nnec

tion

to th

e V

SD

.

4.5.

Ins

ulat

ed N

eutr

al,

“fl o

atin

g” m

ains

pow

er

syst

ems

Shi

ps a

nd o

ther

ves

sels

gen

eral

ly u

se

mai

ns s

uppl

ies

that

do

not h

ave

the

neut

ral o

f the

ir m

ains

pow

er s

uppl

y di

rect

ly b

onde

d to

thei

r ear

th/g

roun

d st

ruct

ure

[35]

, and

som

e la

nd-b

ased

in

stal

latio

ns a

lso

use

this

pra

ctic

e.

This

is k

now

n as

an

IT p

ower

net

wor

k (n

othi

ng to

do

with

Info

rmat

ion

Tech

nolo

gy!).

EN

/IEC

618

00-3

[1] a

ssum

es

(D.1

.2.2

and

D.2

.2) t

hat fi

lter

ing

is

an u

nsui

tabl

e te

chni

que

whe

re th

e m

ains

pow

er n

etw

ork

is is

olat

ed

from

gro

und,

and

say

s th

at in

su

ch s

ituat

ions

the

only

miti

gatio

n po

ssib

le is

to e

nsur

e th

at a

ll th

e ot

her

equi

pmen

t on

the

site

is im

mun

e en

ough

to th

e no

ise

emitt

ed b

y th

e P

DS

. But

this

igno

res

the

poss

ibili

ty o

f in

terfe

renc

e w

ith e

quip

men

t off-

site

, an

d w

ith ra

dio

rece

iver

s, s

o is

not

a

com

plet

e so

lutio

n.

How

ever

, if fi

lter

s ar

e fi t

ted

to

indi

vidu

al B

DM

s as

reco

mm

ende

d in

this

Gui

de, a

ll th

at is

nec

essa

ry

is to

“fl o

at” t

he c

hass

is, f

ram

e or

en

clos

ure

of th

e B

DM

. Sin

ce th

e m

ains

and

out

put fi

lter

s (if

use

d) w

ill

be R

F-bo

nded

dire

ctly

to th

e B

DM

’s

chas

sis,

fram

e or

enc

losu

re th

ey w

ill

not i

ncre

ase

the

leak

age

curr

ent i

nto

the

earth

/gro

und.

Of c

ours

e, th

is w

ill

mea

n pr

otec

ting

the

BD

M fr

om b

eing

to

uche

d, to

pre

vent

per

sonn

el fr

om

suffe

ring

elec

tric

shoc

ks if

ther

e is

a

phas

e-to

-ear

th/g

roun

d fa

ult i

n th

e sy

stem

.

Whe

n us

ing

cabl

e sc

reen

s an

d/or

ar

mou

r ins

tead

of o

utpu

t fi lt

ers,

a

capa

citiv

e R

F-bo

nd c

ould

be

used

at

one

end

of th

e m

otor

cab

le, e

ither

at

the

BD

M o

r in

the

mot

or’s

term

inal

bo

x. T

his

will

not

be

as e

ffect

ive

as

a pr

oper

360

° R

F-bo

nd, b

ut m

ay b

e go

od e

noug

h if

thei

r lea

d le

ngth

s ar

e ke

pt v

ery

shor

t. Fo

r saf

ety,

suc

h sc

reen

-bon

ding

cap

acito

rs s

houl

d be

saf

ety-

rate

d fo

r the

full

phas

e-to

-ph

ase

volta

ge, a

nd o

f cou

rse

thei

r ef

fect

on

the

amou

nt o

f ear

th/g

roun

d

mot

or c

urre

nts

can

also

giv

e ris

e to

si

gnifi

cant

mai

ns v

olta

ge fl

uctu

atio

ns.

This

may

be

able

to b

e cu

red

by

addi

ng in

ertia

l ene

rgy

stor

age

(e.g

. a

larg

er fl

ywhe

el) o

r by

inst

allin

g a

DV

R

with

an

adeq

uate

ratin

g, s

ee 5

.3.9

on

page

48

of [3

0].

4.4.

12.

Rad

iate

d EM

di

stur

banc

es –

low

freq

uenc

y H

-fi el

dsTh

ese

are

supp

ress

ed b

y th

e fi l

terin

g an

d ca

ble

scre

enin

g m

etho

ds

disc

usse

d ea

rlier

, and

by

ensu

ring

that

all

cond

ucto

rs c

arry

ing

DM

loop

s ar

e in

clo

se p

roxi

mity

, pre

fera

bly

twis

ted

toge

ther

, alo

ng th

eir e

ntire

ro

ute,

see

sec

tion

4.4

of [1

9].

Whe

re c

able

s ca

rry

curr

ents

that

are

to

o la

rge

to p

erm

it th

em to

be

twis

ted

or p

lace

d cl

ose

toge

ther

, bec

ause

of

the

phys

ical

dam

age

that

wou

ld

occu

r to

thei

r ins

ulat

ion

due

to th

e el

ectro

-mot

ive

forc

es a

ctin

g on

thei

r co

nduc

tors

, it m

ay b

e po

ssib

le to

ar

rang

e fo

r ext

erna

l shi

eldi

ng a

roun

d th

e bu

ndle

of c

ondu

ctor

s to

pro

tect

ne

arby

equ

ipm

ent f

rom

the

mag

netic

fi e

lds

(see

5.1

2 in

[19]

).

But

shi

eldi

ng c

an b

e ve

ry c

ostly

, es

peci

ally

in th

e ca

se o

f ver

y lo

w

frequ

enci

es –

say

bel

ow 1

kHz

– w

here

it c

an a

lso

be v

ery

diffi

cult

to d

o at

all.

Whe

re p

robl

ems

aris

e w

ith lo

w-

frequ

ency

mag

netic

fi el

d em

issi

ons,

fo

r ins

tanc

e in

a ±

8kA

DC

driv

e I s

aw

in a

ste

el m

ill, o

ften

the

only

sol

utio

ns

are

eith

er to

mak

e su

re th

at s

ensi

tive

equi

pmen

t is

loca

ted

far e

noug

h aw

ay

not t

o be

effe

cted

, use

equ

ipm

ent

that

is n

ot s

ensi

tive

(e.g

. use

pla

sma

or L

CD

com

pute

r scr

eens

inst

ead

of

cath

ode

ray

tube

(CR

T) ty

pes)

, or fi

t lo

calis

ed s

cree

ning

to th

e af

fect

ed

item

s of

equ

ipm

ent.

Scr

eeni

ng fo

r ver

y lo

w fr

eque

ncie

s ca

n be

pas

sive

(e.g

. usi

ng

MuM

etal

TM);

or a

ctiv

e, in

whi

ch m

etal

fra

mew

orks

are

driv

en w

ith c

urre

nts

to c

reat

e m

agne

tic fi

elds

that

“can

cel

out”

the

loca

l am

bien

t mag

netic

fi el

d.

Whe

re th

ere

are

pow

erfu

l cur

rent

s th

ere

is a

lway

s th

e po

ssib

ility

that

hu

man

exp

osur

e to

the

resu

lting

m

agne

tic fi

elds

cou

ld b

e to

o hi

gh, s

ee

[10]

and

[11]

for l

imits

, and

met

hods

fo

r tes

ting

and

calc

ulat

ion.

4.4.

13.

Emis

sion

s fr

om th

e D

C-L

ink

DC

-Lin

k co

nduc

tors

can

car

ry a

s m

uch

nois

e as

the

outp

ut c

able

s.

Figu

re 1

4 sh

ows

that

ther

e is

som

e st

ray

capa

cita

nce

to e

arth

/gro

und

from

the

DC

-Lin

k co

nduc

tors

, so

the

nois

e vo

ltage

s an

d cu

rren

ts o

n th

e D

C-L

ink

can

coup

le n

oise

into

oth

er

equi

pmen

t and

radi

o re

ceiv

ers

by

indu

ctio

n or

radi

atio

n.

The

DC

-Lin

k sh

ould

ther

efor

e be

tre

ated

like

a m

otor

cab

le: m

ade

as s

hort

as p

ract

icab

le, a

nd th

en (i

f

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5455

5.1.

Pow

er q

ualit

y is

sues

Sec

tion

5 of

[30]

is th

e m

ost r

elev

ant

refe

renc

e fo

r ins

talla

tion-

leve

l m

etho

ds fo

r dea

ling

with

poo

r pow

er

qual

ity, a

nd 4

.2 o

f [19

] will

als

o be

us

eful

.

Par

t 6.5

of [

21] d

escr

ibes

a n

umbe

r of

way

s of

des

igni

ng e

quip

men

t to

impr

ove

its im

mun

ity to

pow

er q

ualit

y is

sues

, and

som

e of

thos

e te

chni

ques

ca

n al

so b

e ap

plie

d “s

tand

-alo

ne” t

o a

PD

S, s

yste

m o

r ins

talla

tion.

And

the

tech

niqu

es fo

r dea

ling

with

co

mm

utat

ion

notc

hing

and

oth

er

low

-freq

uenc

y em

issi

ons

such

as

harm

onic

s an

d in

terh

arm

onic

s de

scrib

ed in

sec

tion

4 ab

ove,

may

al

so b

e ab

le to

be

used

to im

prov

e im

mun

ity to

thos

e el

ectro

mag

netic

di

stur

banc

es.

5.2.

Mag

netic

fi el

ds,

cond

ucte

d/ra

diat

ed

dist

urba

nces

, fas

t tra

nsie

nts

Whe

re a

PD

S h

as p

robl

ems

com

plyi

ng w

ith th

e te

sts

for i

mm

unity

to

mag

netic

fi el

ds; c

ondu

cted

co

ntin

uous

EM

dis

turb

ance

s (1

50kH

z to

80M

Hz)

; fas

t tra

nsie

nts,

an

d/or

radi

ated

con

tinuo

us E

M

dist

urba

nces

(80M

Hz

to 1

GH

z)

– th

e us

ual s

olut

ions

are

to u

se th

e fi l

terin

g an

d sc

reen

ing

tech

niqu

es

disc

usse

d in

sec

tion

4 ab

ove

for

supp

ress

ing

emis

sion

s of

low

and

high

freq

uenc

ies.

A te

chni

que

that

atte

nuat

es a

n eq

uipm

ent’s

em

issi

ons

of a

par

ticul

ar

elec

trom

agne

tic d

istu

rban

ce,

gene

rally

pro

vide

s a

sim

ilar l

evel

of

atte

nuat

ion

whe

n pr

otec

ting

equi

pmen

t fro

m in

terfe

renc

e by

that

sa

me

type

of d

istu

rban

ce.

5.3.

Sur

ge tr

ansi

ents

Ser

ies

indu

ctor

s us

ed fo

r sup

pres

sing

em

issi

ons

of h

arm

onic

s or

co

mm

utat

ion

notc

hes

also

hel

p in

crea

se a

driv

e’s

imm

unity

to s

urge

tra

nsie

nts.

Oth

er te

chni

ques

are

ga

lvan

ic is

olat

ion

and

surg

e pr

otec

tion

devi

ces

(SP

Ds)

, whi

ch a

re d

iscu

ssed

in

sec

tions

4.3

and

5.1

3 of

[19]

, re

spec

tivel

y.

Thes

e te

chni

ques

can

be

used

in

divi

dual

ly, o

r tog

ethe

r in

any

com

bina

tion.

5.4.

Ele

ctro

stat

ic d

isch

arge

(E

SD)

ES

D te

chni

ques

for e

quip

men

t are

co

vere

d in

par

t 6.1

of [

21],

and

they

ca

n be

app

lied

to a

com

plet

e B

DM

by

enc

losi

ng it

in e

ither

a p

last

ic

encl

osur

e (to

pre

vent

ES

D fr

om

occu

rrin

g at

all)

or i

n a

shie

lded

en

clos

ure

(to d

iver

t ES

D d

istu

rban

ces

away

from

the

BD

M’s

ele

ctro

nics

w

ithin

).

Pla

stic

enc

losu

res

do n

ot p

rote

ct

leak

age

curr

ent m

ust b

e ta

ken

into

ac

coun

t.

Ano

ther

tech

niqu

e fo

r red

ucin

g th

e ea

rth/g

roun

d le

akag

e of

fi lte

rs a

nd

cabl

e sc

reen

/arm

our b

onds

, is

to fi

t a

co-lo

cate

d is

olat

ing

trans

form

er

to th

e P

DS

so

that

it c

an b

e bo

nded

di

rect

ly to

the

earth

/gro

und

with

out

com

prom

isin

g th

e re

st o

f the

sys

tem

. O

f cou

rse,

if th

e P

DS

is p

ower

ed fr

om

a de

dica

ted

and

co-lo

cate

d st

ep-

dow

n is

olat

ing

mai

ns tr

ansf

orm

er,

a se

para

te is

olat

ing

trans

form

er is

no

t req

uire

d –

its E

MI s

uppr

essi

on

func

tion

is p

rovi

ded

by th

e st

ep-d

own

trans

form

er.

5. I

mm

unity

As

wel

l as

deal

ing

with

em

issi

ons,

E

N/IE

C 6

1800

-3 [1

] spe

cifi e

s te

st

met

hods

and

test

leve

ls fo

r im

mun

ity.

The

issu

es it

is c

once

rned

with

are

:

Pow

er q

ualit

y is

sues

, inc

ludi

ng:

Dis

torte

d m

ains

sup

plie

s (in

clud

ing

harm

onic

dis

torti

on

and

com

mut

atio

n no

tche

s)

Sup

ply

volta

ge d

evia

tions

, va

riatio

ns, c

hang

es, fl

uct

uatio

ns,

dips

, dro

pout

s an

d sh

ort

inte

rrup

tions

Thre

e-ph

ase

volta

ge u

nbal

ance

Mai

ns fr

eque

ncy

varia

tions

Mag

netic

fi el

dsC

ondu

cted

con

tinuo

us E

M

dist

urba

nces

(150

kHz

to 8

0MH

z)Fa

st tr

ansi

ents

Rad

iate

d co

ntin

uous

EM

di

stur

banc

es (8

0MH

z to

1G

Hz)

Sur

ge tr

ansi

ents

Ele

ctro

stat

ic d

isch

arge

Mos

t of t

hese

are

bes

t dea

lt w

ith

by th

e de

sign

of t

he e

quip

men

t, as

de

scrib

ed in

[21]

and

[22]

, and

so

not

in th

e sc

ope

of th

is G

uide

.

To d

iscu

ss w

hat c

an b

e do

ne to

im

prov

e th

e im

mun

ity o

f a P

DS

by

usin

g in

stal

latio

n te

chni

ques

, the

im

mun

ity p

robl

ems

can

be b

roke

n do

wn

into

four

gro

ups,

see

bel

ow.

Page 32: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

5657

7. R

efer

ence

san

d fu

rthe

r rea

ding

[1]

EN

618

00-3

:200

4, “A

djus

tabl

e S

peed

Ele

ctric

al P

ower

Driv

e S

yste

ms

– P

art 3

: EM

C

requ

irem

ents

and

spe

cifi c

test

m

etho

ds”.

Iden

tical

to IE

C

6180

0-3:

2004

.

[2]

Eur

opea

n U

nion

Dire

ctiv

e 20

04/1

08/E

C (a

s am

ende

d) o

n E

lect

rom

agne

tic C

ompa

tibili

ty

(2nd

Edi

tion)

in E

nglis

h: h

ttp://

eur-

lex.

euro

pa.e

u/Le

xUriS

erv/

site

/en/

oj/2

004/

l_39

0/l_

3902

0041

231e

n002

4003

7.pd

f

– in

any

EU

lang

uage

: http

://ec

.eur

opa.

eu/e

nter

pris

e/el

ectr_

equi

pmen

t/em

c/di

rect

iv/d

ir200

4_10

8.ht

m

The

Dire

ctiv

e’s

offi c

ial

EU

hom

epag

e in

clud

es a

do

wnl

oada

ble

vers

ion

of th

e cu

rren

t EM

C D

irect

ive

and

its

succ

esso

r; a

tabl

e of

all

the

EN

sta

ndar

ds li

sted

und

er

the

Dire

ctiv

e; a

gui

danc

e do

cum

ent o

n ho

w to

app

ly th

e D

irect

ive;

list

s of

app

oint

ed E

MC

C

ompe

tent

Bod

ies;

etc

., al

l at

: ht

tp://

euro

pa.e

u.in

t/com

m/

ente

rpris

e/el

ectr_

equi

pmen

t/em

c/in

dex.

htm

.

[3]

Kei

th A

rmst

rong

, “C

ompl

ying

w

ith th

e E

MC

Dire

ctiv

e (2

004/

108/

EC

), S

econ

d E

ditio

n”,

Con

form

ity, M

arch

200

8, p

ages

12

-22,

http

://w

ww

.con

form

ity.

com

/PD

Fs/0

803/

0803

_F1.

pdf.

Als

o pu

blis

hed

in a

slig

htly

am

ende

d fo

rm in

Con

form

ity’s

20

09 A

nnua

l Ref

eren

ce G

uide

.

[4]

Sev

ente

en E

MC

Gui

des

on E

M

phen

omen

a, le

gal c

ompl

ianc

e an

d E

MC

test

ing

have

bee

n w

ritte

n by

Kei

th A

rmst

rong

an

d pu

blis

hed

by R

EO

(UK

) Lt

d. T

hey

are

very

read

able

an

d pr

actic

al, a

nd c

an b

e do

wnl

oade

d fro

m w

ww

.reo.

co.u

k/kn

owle

dgeb

ase.

They

are

als

o av

aila

ble

from

R

EO

(UK

) Ltd

and

Che

rry

Clo

ugh

Con

sulta

nts

as a

CD

-R

OM

that

con

tain

s al

l 17

of th

em

plus

two

othe

r RE

O E

MC

Gui

des

and

a gr

eat d

eal o

f oth

er u

sefu

l in

form

atio

n on

EM

C.

[5]

“On-

Site

EM

C T

est M

etho

ds”,

Kei

th A

rmst

rong

, EM

C T

est L

abs

Ass

ocia

tion

(ww

w.e

mct

la.c

o.uk

) Te

chni

cal G

uida

nce

Not

e N

o.

TGN

49,

als

o av

aila

ble

from

the

“Pub

licat

ions

and

Dow

nloa

ds”

page

s at

ww

w.c

herr

yclo

ugh.

com

.

[6]

The

EC

’s o

ffi ci

al G

uide

to

2004

/108

/EC

can

be

dow

nloa

ded

from

: http

://ec

.eur

opa.

eu/

ente

rpris

e/el

ectr_

equi

pmen

t/em

c/di

rect

iv/d

ir200

4_10

8.ht

m#g

uide

from

the

radi

ated

fi el

ds o

f a n

earb

y di

scha

rge,

so

it m

ay tu

rn o

ut th

at a

sh

ield

ing

solu

tion

is b

ette

r. Th

is is

th

en ju

st a

mat

ter o

f app

lyin

g th

e sh

ield

ing

tech

niqu

es b

riefl y

intro

duce

d in

4.4

.5 a

bove

, usu

ally

aim

ing

for t

he

uppe

r fre

quen

cy to

be

cont

rolle

d to

be

at le

ast 1

GH

z, id

eally

3G

Hz.

To s

uppr

ess

ES

D w

ithin

an

inst

alla

tion

mea

ns p

reve

ntin

g it

from

hap

peni

ng

by u

sing

sta

tic c

ontro

l mea

sure

s:

diss

ipat

ive

fl oor

ing

and

othe

r sur

face

s,

diss

ipat

ive

clot

hing

, ion

isin

g bl

ower

s,

cont

rol o

f rel

ativ

e hu

mid

ity e

tc.,

all

very

fam

iliar

to a

nyon

e w

ho h

as

wor

ked

in s

emic

ondu

ctor

man

ufac

ture

or

ligh

t ele

ctro

nic

asse

mbl

y.

6. E

MC

sup

pres

sion

pr

oduc

ts fr

om R

EOFi

gure

28

show

s th

e ra

nge

of p

rodu

cts

that

RE

O p

rovi

des

for s

uppr

essi

ng

and/

or p

rote

ctin

g m

otor

driv

es.

L1 L2 L3

M 3

Inpu

t Filt

erLi

ne In

duct

or

Com

bine

d Fi

lter I

nduc

tor

DC

Lin

k C

hoke

Bra

king

Res

isto

r

dV/d

tFi

lter

Mot

orIn

duct

or

Sin

usoi

dal

Filte

r

DC

Con

verte

rP

WM

Inve

rter

Out

put F

ilter

Figu

re 2

8: R

EO’s

mot

or d

rive

prod

ucts

Page 33: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

5859

Mor

e “B

anan

a S

kins

” are

pu

blis

hed

6 tim

es a

yea

r in

“The

E

MC

Jou

rnal

”, av

aila

ble

free

at

ww

w.th

eem

cjou

rnal

.com

or w

ww

.co

mpl

ianc

e-cl

ub.c

om.

[16]

IEC

TS

610

00-1

-2, b

asic

saf

ety

publ

icat

ion,

dra

ft se

cond

edi

tion,

Ja

nuar

y 20

08, “

Ele

ctro

mag

netic

C

ompa

tibili

ty (E

MC

) – P

art 1

-2:

Gen

eral

– M

etho

dolo

gy fo

r the

ac

hiev

emen

t of t

he fu

nctio

nal

safe

ty o

f ele

ctric

al a

nd e

lect

roni

c eq

uipm

ent w

ith re

gard

to

elec

trom

agne

tic p

heno

men

a.”

[17]

The

IET,

“Gui

de o

n E

MC

for

Func

tiona

l Saf

ety”

, Aug

ust 2

008,

IS

BN

978

-0-9

5551

18-2

-0

Cos

t £27

plu

s p&

p fro

m h

ttp://

ww

w.e

mca

cade

my.

org/

book

s.as

p or

free

dow

nloa

d fro

m w

ww

.th

eiet

.org

/fact

fi les

/em

c/in

dex.

cfm

.

[18]

The

“Mac

hine

ry S

afet

y D

irect

ive”

: “D

irect

ive

98/3

7/E

C o

f the

E

urop

ean

Par

liam

ent a

nd o

f th

e C

ounc

il of

22

June

199

8 on

th

e ap

prox

imat

ion

of th

e la

ws

of

the

Mem

ber S

tate

s re

latin

g to

m

achi

nery

The

new

Mac

hine

ry S

afet

y D

irect

ive:

“Dire

ctiv

e 20

06/4

2/E

C

of th

e E

urop

ean

Par

liam

ent a

nd

of th

e C

ounc

il of

17

May

200

6 on

mac

hine

ry, a

nd a

men

ding

D

irect

ive

95/1

6/E

C (r

ecas

t)”

[19]

RE

O G

uide

on

“Goo

d E

MC

E

ngin

eerin

g P

ract

ices

in th

e D

esig

n an

d C

onst

ruct

ion

of F

ixed

Inst

alla

tions

”, fre

e do

wnl

oad

from

: ww

w.re

o.co

.uk/

know

ledg

ebas

e

[20]

RE

O G

uide

on

“Goo

d E

MC

E

ngin

eerin

g P

ract

ices

in th

e D

esig

n an

d C

onst

ruct

ion

of In

dust

rial C

abin

ets”

, av

aila

ble

from

ww

w.re

o.co

.uk/

know

ledg

ebas

e

[21]

Kei

th A

rmst

rong

, “D

esig

n Te

chni

ques

for E

MC

” in

six

parts

, The

EM

C J

ourn

al, I

ssue

62

thro

ugh

Issu

e 77

(Jan

uary

20

06 th

roug

h Ju

ly 2

008)

, ww

w.

thee

mcj

ourn

al.c

om, (

sear

ch b

y “K

eith

Arm

stro

ng”)

[22]

Kei

th A

rmst

rong

, “E

MC

for

Prin

ted

Circ

uit B

oard

s –

Bas

ic

and

Adv

ance

d D

esig

n an

d La

yout

Tec

hniq

ues”

, Nut

woo

d/A

rmst

rong

, Feb

ruar

y 20

07, £

47

plus

p&

p.

Per

fect

bou

nd (w

ith ti

tled

spin

e):

ISB

N 9

78-0

-955

5118

-1-3

Spi

ral b

ound

(lay

s fl a

t):

ISB

N 9

78-0

-955

5118

-0-6

Ord

er v

ia h

ttp://

ww

w.

emca

cade

my.

org/

book

s.as

p

[23]

Kei

th A

rmst

rong

, “B

OM

Cos

t and

P

rofi t

abili

ty”,

The

EM

C J

ourn

al,

Issu

e 82

, May

200

9, p

ages

32-

34, w

ww

.thee

mec

jour

nal.c

om

[7]

The

EM

C R

egul

atio

ns 2

006,

U

nite

d K

ingd

om S

tatu

tory

In

stru

men

t 200

6 N

o. 3

418:

http

://w

ww

.ops

i.gov

.uk/

si/s

i200

6/uk

si_

2006

3418

_en.

pdf,

impl

emen

ting

2004

/108

/EC

in U

K la

w.

[8]

The

offi

cial

gui

de to

the

UK

’s

2006

EM

C R

egul

atio

ns is

pos

ted

unde

r “R

elat

ed D

ocum

ents

” at

: http

://w

ww

.ber

r.gov

.uk/

dius

/in

nova

tion/

regu

latio

ns/e

cdire

ct/

page

1246

9.ht

ml

[9]

The

cons

olid

ated

ver

sion

of t

he

Low

Vol

tage

Dire

ctiv

e, 2

006/

95/

EC

, rep

lace

s 73

/23/

EE

C a

nd it

s am

endm

ent b

y 93

/68/

EE

C, h

ttp://

euro

pa.e

u.in

t/com

m/e

nter

pris

e/el

ectr_

equi

pmen

t/lv/

inde

x.ht

m

[10]

199

9/51

9/E

C, “

Cou

ncil

reco

mm

enda

tion

1999

/519

/EC

on

the

limita

tion

of e

xpos

ure

of th

e ge

nera

l pub

lic to

el

ectro

mag

netic

fi el

ds (0

Hz

to 3

00 G

Hz)

”, fro

m: h

ttp://

ec.e

urop

a.eu

/ent

erpr

ise/

elec

tr_eq

uipm

ent/l

v/em

f.htm

[11]

EN

623

11:2

008,

“Gen

eric

st

anda

rd to

dem

onst

rate

th

e co

mpl

ianc

e of

ele

ctro

nic

and

elec

trica

l app

arat

us

with

the

basi

c re

stric

tions

re

late

d to

hum

an e

xpos

ure

to

elec

trom

agne

tic fi

elds

(0 H

z -

300

GH

z)” (

a m

odifi

ed v

ersi

on o

f IE

C 6

2311

:200

7, it

repl

aces

EN

50

392:

2004

).

[12]

200

4/40

/EC

, “O

n th

e m

inim

um

heal

th a

nd s

afet

y re

quire

men

ts

rega

rdin

g th

e ex

posu

re o

f w

orke

rs to

the

risks

aris

ing

from

ph

ysic

al a

gent

s (e

lect

rom

agne

tic

fi eld

s) (1

8th

indi

vidu

al D

irect

ive

with

in th

e m

eani

ng o

f Arti

cle

16(1

) of D

irect

ive

89/3

91/E

EC

)”,

date

d 29

Apr

il 20

04. F

rom

: ht

tp://

ww

w.h

se.g

ov.u

k/ra

diat

ion/

noni

onis

ing/

l184

emf.p

df

[13]

EN

/IEC

618

00-5

-2, “

Adj

usta

ble

spee

d el

ectri

cal p

ower

driv

e sy

stem

s –

Par

t 5-2

: Saf

ety

requ

irem

ents

– F

unct

iona

l”

[14]

IEC

615

08: “

Func

tiona

l Saf

ety

of E

lect

rical

, Ele

ctro

nic

and

Pro

gram

mab

le E

lect

roni

c S

yste

ms”

(sev

en p

arts

)

[15]

The

Firs

t 500

“Ban

ana

Ski

ns”,

Nut

woo

d U

K, 2

007,

500

repo

rts

and

anec

dote

s co

ncer

ning

el

ectro

mag

netic

inte

rfere

nce

(EM

I). R

ead

it at

ww

w.

thee

mcj

ourn

al.c

om, o

r buy

fro

m p

am@

nutw

ood.

eu.c

om

(app

roxi

mat

ely

£10)

or v

ia h

ttp://

ww

w.e

mca

cade

my.

org/

book

s.as

p.

Num

bers

: 1, 1

8, 5

0, 1

01, 1

62,

168,

233

, 274

, 278

, 279

, 282

, 32

4, 4

33, 4

38, 4

55, 4

69, 4

83

conc

ern

inci

dent

s as

soci

ated

w

ith s

witc

h-m

ode

pow

er

conv

ersi

on, i

nclu

ding

var

iabl

e sp

eed

mot

or d

rives

.

Page 34: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

6061

Inte

rnat

iona

l EM

C S

ympo

sium

, A

ustin

Tex

as, U

SA

, 17-

22 A

ugus

t 20

09, I

SB

N: 9

78-1

-424

4-42

85-0

EN

and

IEC

sta

ndar

ds m

ay b

e pu

rcha

sed

from

Brit

ish

Sta

ndar

ds

Inst

itutio

n (B

SI)

at: o

rder

s@bs

i-glo

bal.

com

. To

enqu

ire a

bout

a p

rodu

ct o

r se

rvic

e ca

ll B

SI C

usto

mer

Ser

vice

s on

+44

(0)2

0 89

96 9

001

or e

-mai

l th

em a

t cse

rvic

es@

bsi-g

loba

l.com

. IE

C s

tand

ards

can

als

o be

pur

chas

ed

with

a c

redi

t car

d, in

Eng

lish

and

man

y ot

her l

angu

ages

, fro

m h

ttp://

web

stor

e@ie

c.ch

.

[24]

Kei

th A

rmst

rong

, “G

ettin

g W

hat

You

Wan

t”, T

he E

MC

Jou

rnal

, Is

sue

77, J

uly

2008

, pag

es 1

9-21

, ww

w.th

eem

cjou

rnal

.com

[25]

Kei

th A

rmst

rong

, “A

bsen

ce o

f P

roof

is N

ot P

roof

of A

bsen

ce

(and

the

“pro

ven

in u

se” f

alla

cy)”

, Th

e E

MC

Jou

rnal

, Iss

ue 7

8,

Sep

tem

ber 2

008,

pag

es 1

6-20

, w

ww

.thee

mcj

ourn

al.c

om

[26]

Tim

Will

iam

s an

d K

eith

A

rmst

rong

, “E

MC

for S

yste

ms

and

Inst

alla

tions

”, N

ewne

s,

2000

, IS

BN

: 0-7

506-

4167

-3,

ww

w.b

h.co

m/n

ewne

s, R

S

Com

pone

nts

16/N

o. 3

77-6

463,

(a

ppro

xim

atel

y £4

7, p

aper

back

)

[27]

Kei

th A

rmst

rong

, “Th

e Tr

uth

of M

urph

y’s

Law

”, Th

e E

MC

Jo

urna

l, Is

sue

79, N

ovem

ber

2008

, pag

es 1

6-18

, ww

w.

thee

mcj

ourn

al.c

om

[28]

Pul

se-W

idth

Mod

ulat

ion

(PW

M),

see:

http

://en

.wik

iped

ia.o

rg/w

iki/

Pul

se-w

idth

_mod

ulat

ion

[29]

RE

O (U

K) L

td G

uide

on

“Har

mon

ics”

, ava

ilabl

e fro

m

ww

w.re

o.co

.uk/

know

ledg

ebas

e.

[30]

RE

O G

uide

on

“Pow

er Q

ualit

y”,

avai

labl

e fro

m w

ww

.reo.

co.u

k/kn

owle

dgeb

ase.

[31]

RE

O G

uide

on

“Pow

er Q

ualit

y fo

r Var

iabl

e S

peed

Driv

es”,

free

dow

nloa

d fro

m: w

ww

.reo.

co.u

k/kn

owle

dgeb

ase

[32]

“Var

iabl

e S

peed

Driv

es –

A G

uide

to

Sup

ply

Har

mon

ics

and

Oth

er

Low

-Fre

quen

cy D

istu

rban

ces”

, E

mer

son

Indu

stria

l Aut

omat

ion,

fre

e do

wnl

oad

from

: ww

w.

cont

rolte

chni

ques

.com

/gui

des

[33]

“A G

uide

to E

lect

rom

agne

tic

Com

patib

ility

(EM

C) f

or

Varia

ble

Spe

ed D

rives

”, E

mer

son

Indu

stria

l Aut

omat

ion,

fre

e do

wnl

oad

from

: ww

w.

cont

rolte

chni

ques

.com

/gui

des

[34]

“Con

trol T

echn

ique

s D

rives

and

C

ontro

ls H

andb

ook,

2nd

Edi

tion”

, B

ill D

rury

, IE

T pu

blis

hers

, 200

9,

ISB

N 9

78-1

-849

19-0

13-8

, ww

w.

thei

et.o

rg/p

ublis

hing

/boo

ks/

pow

-en/

cont

rol-t

echn

ique

s-2n

d-ed

.cfm

[35]

Am

eric

an B

urea

u of

Shi

ppin

g,

“Gui

danc

e N

otes

on

Con

trol o

f H

arm

onic

s in

Ele

ctric

al P

ower

S

yste

ms”

, May

200

6, fr

ee

dow

nloa

d fro

m: w

ww

.eag

le.

org/

absd

ownl

oads

/get

pub.

cfm

?pub

=150

[36]

EP

RI,

“Tro

uble

-Sho

otin

g G

uide

fo

r Low

-Vol

tage

AS

D/M

otor

S

yste

ms”

, TR

-110

97, fi

nal

repo

rt N

ovem

ber 1

998,

free

dow

nloa

d:

http

://m

ydoc

s.ep

ri.co

m/d

ocs/

publ

ic/T

R-1

1109

7.pd

f

[37]

K O

Phi

pps,

P F

Kee

bler

and

R

F A

rritt

, “R

eal W

orld

AS

D

Inte

rfere

nce

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Page 35: Another EMC resource from EMC Standards...Helping you solve your EMC problems 9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk Another EMC

62 Kei

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