eliminating harmonic neutral current problems

8/11/2019 Eliminating Harmonic Neutral Current Problems

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Presented by

Michael Z. Lowenstein, Ph.D.

Chief Technology Officer

Harmonics Limited

Eliminating Harmonic Neutral

Current Problems

Powering multiple computer loads createsproblems in electrical distribution systems.

Harmonic current flow generates heat in allparts of the distribution system, whichwastes energy.

Ridding the system of harmonic current flowsaves energy and money.

Basic Premises


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Why there is a problem

Power dist ribut ion in a Wye system

Powering computers

Accommodating harmonic currents

Preventing harmonic currents with theHarmonic Suppression System (HSS)

Saving energy

HSS products Who uses the HSS and the results they

obtain

Outline

When an electric motor is connected to theAC l ine, i t draws i ts power directly from theline. The power is not treated in any way.

The same is true for a resist ive load such asan electr ic heater.

Linear loads


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Voltage & currenthave the samemathematicalrelationship acrossthe entire cycle

PEAKS ZERO CROSSINGS

CURRENTVOLTAGE

0 180 360

AMPLITUDE

WAVE ANGLE

Linear voltage-current relationship

When a computer is connected to theAC line, it draws its power from aninternal DC supply that containsrectifiers and capacitors.

Non-linear loads


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Non-linear voltage-current relationship

Mathematicalrelationshipsbetween voltage& current varyacross the cycle

PEAKS ZERO CROSSINGS

VOLTAGECURRENT

0 180 360

AMPLITUDE

WAVE ANGLE

Linear & non-linear loads (1)

Linear Load Thecurrent looks l ikethe voltage

The more the currentlooks l ike thevoltage, the morelinear is the load

Non-linear LoadThe current doesnot look like thevoltage


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Linear Loads gettheirkW power at60 Hz.

Non-linear loads gettheir kW power at 60Hz and in additiondraw harmoniccurrents

Linear & non-linear loads (2)

What are harmonics?

3rd HARMONIC

5th HARMONIC

FUNDAMENTAL

0 90 180 270 360WAVE ANGLE

AMPLITUDE

Harmonics are continuousintegral mult iples of thefundamental frequency


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FREQUENCYFREQUENCYHARMONIC

1

2

3

5

7

9

11

49

60

120

180

300

420

540

660

2940

400

800

1200

2000

2800

3600

4400

19600

Table of harmonics

Single-phase 2-pulse diode bridge(computer power supply)

+

_

CAPACITIVE LOAD


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Single-phase 2-pulse diode bridge(waveform)

VOLTS

AMPS

0 90 180 270 360 450 540 630 720

WAVE ANGLE IN DEGREES

13

57

911

1315

1719

0

10

20

30

40

50

60

70

80

90

100

C

URRENT%F

UNDAMENTAL

HARMONIC NUMBER

Single-phase harmonic spectrum(typical for personal computers)


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3-phase wye

distribution systems(with phase-to-neutral loads)

Wye distribution system

Serving Linear Loads

TRANSFORMER ENCLOSUREPHASE C

PHASE A

PHASE B

60HzCURRENTS

60Hz CURRENT

60Hz IMBALANCE CURRENT ONLY

PRIMARY CIRCUITBREAKER

TO BUILDING STEEL

X0

HEATER HEATER HEATER


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Standard t ransformer, phase A

linear load

A = 12.4 Amps; B = 0.8 Amps; C = 0.8 Amps; N = 12.2 Amps

Standard t ransformer, phases A + B

linear load

A = 12.4 Amps; B = 11.9 Amps; C = 0.7 Amps ; N = 11.9 Amps


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Standard transformer, phases A + B + C

linear load


Harmonics currents do no work, but docontribute to the rms current the system mustcarry

3rd harmonic currents are additive in thesystem neutral

3rd harmonic currents return to thetransformer over the neutral and are dissipatedas heat in the transformer, cables and loaddevices

Reasons to be concerned about

harmonic currents


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PHASE C

PHASE A

60Hz IMBALANCE CURRENT +SUMMED 3rd HARMONIC CURRENT

PHASE B

3rd HARMONIC CURRENTCIRCULATES IN DELTA WINDING

SAFETYGROUND

TRANSFORMER ENCLOSURE

60Hz CURRENT +HARMONIC CURRENT60Hz ANDNON-TRIPLEN

HARMONICCURRENTS

TO BUILDING STEEL

COMPUT ER COMPUT ER COMPUT ER


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Wye Distribution System

Serving Non-Linear Loads

Standard Transformer, 10 non-linear loads,

phase A



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A = 24.7 Amps; B = 23.4 Amps; C = 0.7 Amps ; N = 33.9 Amps


phases A + B



phases A + B + C


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k-Rated Transformers

Double Neutrals

Oversized switch gear

De-rated UPSs, and Power DistributionUnits (PDUs)

Zig-zag or phase shifting transformers

Avoiding Harmonic Problems(Accommodation)

PHASE C

PHASE A


PHASE B

3rd HARMONIC CURRENTCIRCULATES IN DELTA WINDING

SAFETYGROUND


60Hz CURRENT +HARMONIC CURRENT60Hz ANDNON-TRIPLEN

HARMONICCURRENTS

TO BUILDING STEEL

COM PUTER COMPUTER COM PUTER


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K-rated transformer to accommodate

harmonic currents


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K-rated transformer, 10 non-linear loads, phases

A+B+C


Double Neutrals


De-rated UPSs, and Power Distribution

Units (PDUs) Zig-zag or phase shifting transformers

Avoiding Harmonic Problems

(Accommodation)


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Double Neutrals


De-rated UPSs, and Power DistributionUnits (PDUs)

Zig-zag or phase shifting transformers

Avoiding Harmonic Problems(Accommodation)

Zig-zag transformer to accommodate

harmonic currents

PHASE C

PHASE A

PHASE B

3rd HARMONIC CURRENT DISSIPATEDAS HEAT IN SECONDARY WINDING

SAFETYGROUND


60Hz CURRENT +HARMONIC CURRENT

TO BUILDING STEEL

COM PUTER COMPUTER COM PUTER

60Hz ANDNON-TRIPLENHARMONICCURRENTS




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zig-zag transformer, 10 non-linear loads, phases

A+B+C

Introducing the Harmonic SuppressionSystem (HSS)

Blocks 3rd harmonic currents andprevents their flow anywhere in thesystem

Eliminates need for oversized componentsand doubled neutrals.

Minimizes waste heat from the transformerout to the furthest outlet.

Eliminating Harmonic Problems


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3rd

HARMONICFLOW

HSS blocking 3rd harmonic currents

SINCE NO 3rd HARMONICCURRENT CAN RETURN IN THE

NEUTRAL WIRE, NO 3rdHARMONIC CURRENT CAN FLOW

IN THE PHASE WIRES.

60Hz CURRENT and 3rd HARMONICCURRENT FLOWING IN ALL THREEPHASES

60 Hz 3rdHARMONIC

PHASE C

PHASE A

PHASE B

COMPUTER COMPUTER COMPUTER

60Hz IMBALANCE CURRENT PLUS 3RD HARMONICCURRENT, COMBINED FROM ALL THREE PHASES, MUST

RETURN TO THE TRANSFORMER ON THE NEUTRAL WIRE`

NEUTRAL

X0

RLC Parallel-Resonant Tank Circui t HSS)


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TRANSFORMER ENCLOSUREPHASE C

PHASE A

PHASE B

60Hz ANDNON-TRIPLENHARMONICCURRENTS

COMPUTER COMPUTER COMPUTER

HSS

NO 3rd HARMONIC CURRENTSTO CIRCULATE IN DELTA WINDING

60Hz CURRENT & HARMONIC-CURRENTS OTHER THAN 3RD

60Hz IMBALANCE CURRENT ONLYIN COMBINED NEUTRAL


TO BUILDING STEEL

X0

HSS ENCLOSURE

Wye distribution system with HSS

Computer Current (With & Without HSS)

no HSS

HSS


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With HSS Without HSS

1 3 5 7 9 11 13 15 17 19

0102030405060708090

100

1 3 5 7 9 11 13 15 17 19

%o

fFundamental

Phase Harmonic Currents With & WithoutHarmonic Suppression System

Neutral Harmonic Currents With &

Without Harmonic Suppression System

With HSS Without HSS

1 3 5 7 9 11 13 15 17 19

0255075

100125150175200225250

1 3 5 7 9 11 13 15 17 19

Currentinamps


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Reduces neutral currents by more than90% by preventing 3rd harmoniccurrent flow (from the transformer out tothe furthest outlet)

Lowers rms phase currents, leading tomore useable capacity without the needto install a larger system.

Reduces energy losses throughout thesystem

What the HSS Does (for your system)

Proper Sizing of the Distribution System

System over-sizing to handleharmonic currents is eliminated.

Useable system capacity isincreased (single phase power factoris improved.)


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Power factor is defined as activepower divided by apparent power

Power factor can be described as ameasure of the effective util ization ofelectrical system capacity

Single-phase power factor

System Capacity

Unloaded system


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System Capacity

kW Power

Harmonics

Low power factor

System Capacity

kW Power

Harmonics

Slightly improved power factor


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System CapacitykW Power

Harmonics

High power factor

*Single-phase power factor, is a measure of

the efficiency of system capacity utilization.

TEST VOLTAGE

(rms volts)

CURRENT

(rms amps)

WATTS VOLT-

AMPS

POWER

FACTOR*

No HSS 116.7 4.972 360.4 580.4 0.62

With HSS 117.2 3.173 355.9 371.8 0.96

Single-phase power factor(with and wi thout the HSS)


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System-wide I2R energy losses

Losses due to system-wide heating showup on the energy bi ll as increased kWHusage

The HSS reduces system-wide heatingand provides real energy savings.

This savings can be measured byexamining a system with and without anHSS installed

Measurements both in the laboratory andin the field conf irm system-wide energysavings.

Power saved by removing harmonic currents

varies with system loading and wiring method

% kW REDUCTION WITH VARYING WIRING OPTIONS

AND LOADING, STANDARD TRANSFORMER

0

1

2

3

4

5

6

7

8

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

% TRANSFORMER LOADING

%

kW

REDUCTION

50' 50'+100' SN 50'+ 100'CN 50'+100' SN+100'CN


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The Energy Savings Estimator

The energy savings estimator

(I2R waste heat savings)


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The energy savings estimator(avoided air conditioning)

Secondary currents (by transformer type)

0

5

10

15

20

25

30

35

40

45

CURRENTINAMP

std xfmr k-rated xfmr Zig-zag xfmr

TRANSFORMER TYPE

SECONDARY CURRENT BY PHASE AND TRANSFORMER TYPE (WITH

HARMONICS) 50' + 100' COMMON NEUTRAL

p has e a pha se b p has e c neutral


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0

5

10

15

20

25

30

35

40

45

CURRENTINAMP

std xfmr k-rated xfmr Zig-zag xfmr

TRANSFORMER

SECONDARY CURRENT BY PHAS E AND TRANSFORMER TYPE (HARMONICS

SUPPRESSED) 50' +

100' COMMON NEUTRAL

phas e a phas e b phas e c neutral

Secondary currents (by transformer type)with HSS

6.20

6.30

6.40

6.50

6.60

6.70

6.80

6.90

7.00

7.10

POWERINk

st d x fmr k -r at ed x fmr z ig- zag x fmr

TRANSFORMER TYPE

POWER BY TRANSFORMER TYPE (WITH AND WITHOUT

HARMONICS) 50' + 100' COMMON NEUTRAL

SOLID = WITH CHECKERED = WITHOUT

Power with and without HSS

(by transformer type)


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-8.00%

-7.00%

-6.00%

-5.00%

-4.00%

-3.00%-2.00%

-1.00%

0.00%

1.00%

2.00%

3.00%

PERCENTCHANGEIN

POWERUSED

std x fmr k-rated x fmr zig-zag xfmr

TRANSFORMER TYPE

COMPARISON OF POWER USED, BY TRANSFORMER TYPE

(PERCENT INCREASE OR DECREASE) 50' + 100' COMMON

NEUTRAL (PAGE 2)

CHANGE IN POWER USE COMPARED TO STANDARD TRANSFORMER

CHANGE IN POWER USE WITH HARMONIC REMOVAL

Power used with and without HSS, change(by transformer type)

Harmonic Suppression Products


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The SysteMax

is an add-on

Harmonic

Suppression

System That can be

added to your

present transformer

to remove harmonic

currents

The TransMaxcombines a high

quality TP-1 (formerly

energy star)

transformer with the

Harmonic

Suppression Systemin a single easy-to-

install enclosure.


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500 kVA TransMax(installed in a basement vault)

Who uses the HSS and why?

Data Centers

Financial institutions

Government institutions

Casinos

Educational institutions

Hospitals

Research laboratories


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Stock exchange trading room floor

Transformers2- 112 kVA & 1-75 kVA, K-20 TransformersAvg. transformer loading 64% of Rated

Capacity

Combined Neutral Current reduced by75%, from 750 amps., to 186 amps..

3rd Harmonic Neutral Current reduced by98%, from 712 amps., to 15 amps.,

RMS Phase Current reduced by 9% Using energy savings estimator-- ROI, 19

months 3 Portable A/C units removed ($54,000.00

per yr.)


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Software development center(before and after HSS)

Every electrical distribution system poweringmultiple single-phase non-linear loads, issusceptib le to harmonic neutral currentproblems

Installing a Harmonic Suppression Systemincreases electrical system reliabili ty

Installing a Harmonic Suppression Systemreduces heat and wasted energy system-wide

Using the HSS saves you energy and money

Conclusions


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CONTACT INFORMATION

Michael Z. Lowenstein

Harmonics Limited

2400 Ardmore Blvd., Suite 302

Pittsburgh, PA 15221

Phone: 412-636-9600 ext 3

Cell: 970-216-4515

[email protected]

eliminating harmonic neutral current problems

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