SINGLE LINE DIAGRAM (SLD) Or, ONE LINE DIAGRAM Date: drafted 11th January 2015 WHY IT’S REQUIRED? Whether you have a new or existing facility, the single-line diagram is the vital roadmap for all future testing, service and maintenance activities. As such, the single-line diagram is like a balance sheet for your facility and provides a snapshot of your facility at a moment in time. It needs to change as your facility changes to ensure that your systems are adequately protected. To make all the changes documented in a common file, making the electrical system easily understandable for any technical person inside/outside of the factory. An up-to-date single-line diagram is vital for a variety of service activities including:

• Short circuit calculations • Coordination studies • Load flow studies • Safety evaluation studies • All other engineering studies • Electrical safety procedures • Efficient maintenance

WHAT SHOULD BE IN A SINGLE LINE DIAGRAM (SLD)? A typical package of single line diagram shall include:

• Incoming lines showing voltage and size • Incoming main fuses, cutouts, switches, and main/tie breakers • Power transformers (rating, winding connection and grounding means) • Feeder breakers and fused switches rating and type. • Relays (function, use and type) • Current and / or potential transformers with size, type and ratio • Control transformers rating. • All main cable and wire runs with their associated isolating switches • All substations, including integral relays and main panels with total load of each feeder and

each substation • Critical equipment voltage and size (UPS, battery, generator, power distribution, transfer

switch, computer room air conditioning) • A summary load schedule for the LT switchgear panel. • A load schedule for each distribution panels and switch board. • Rating and dimension of bus bar. • All outgoing cables with cable size and type with rating and type of their associated isolating

switches (e.g. circuit breaker). • Length and voltage drop of all outgoing cables. • Rating of PFI , changeover, ATS, generators with associated protection and isolating switch • All earthing cable rating (size, type etc.) • All connected load with their individual load capacity. • All spare switches (outgoing circuit breaker) shall be mentioned. • Earthing system must be included with dimension of earthing pit, boring, earth electrode size,

earth lead and ECC cable size and type. Here is given an example of a typical LT panel one line diagram or Single line diagram (try to follow it as best as possible).

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

LOAD

SCH

EDU

LE &

SIN

GLE

LIN

E D

IAG

RAM

OF

SM

DB-S

(SEC

ON

D F

LOO

R)

MEP

CONS

ULTA

NT:

Note

:

x x x x

R=49

.330

KW

Y=49

.340

KW

B=49

.330

KW

TL=1

48.0

00 K

WDL

=103

.600

KW

(70%

)

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

SIN

GLE

LIN

E D

IAG

RAM

OF

SM

DB-F

OF

FIRST

FLO

OR

MEP

CONS

ULTA

NT:

Note

:

x x x x

R=49

.340

KW

Y=49

.330

KW

B=49

.330

KW

TL=1

48.0

00 K

WDL

=103

.600

KW

(70%

)

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

SIN

GLE

LIN

E D

IAG

RAM

OF

SM

DB-T

OF

THIR

D F

LOO

R

MEP

CONS

ULTA

NT:

Note

:

x x x x

R=19

.720

KW

Y=19

.720

KW

B=19

.720

KW

TL=5

9.16

0 KW

DL=4

1.41

2 KW

(70%

)

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

LOAD

SCH

EDU

LE &

SIN

GLE

LIN

E D

IAG

RAM

OF

SM

DB-F

r. (

FOU

RTH

FLO

OR)

MEP

CONS

ULTA

NT:

Note

:

x x x x

R=49

.330

KW

Y=49

.330

KW

B=49

.340

KW

TL=1

48.0

00 K

WDL

=103

.600

KW

(70%

)

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

LOAD

SCH

EDU

LE &

SIN

GLE

LIN

E D

IAG

RAM

OF

SM

DB-F

f. (

FIFT

H F

LOO

R)

MEP

CONS

ULTA

NT:

Note

:

x x x x

R=49

.340

KW

Y=49

.330

KW

B=49

.330

KW

TL=1

48.0

00 K

WDL

=103

.600

KW

(70%

)

M

2x1c

,120

.0 m

m2

Cu.

R=27

3.46

5 KW

Y=27

3.22

0 KW

B=27

2.44

5 KW

TL=8

19.1

30 K

W

R=55

.296

KW

Y=55

.060

KW

B=54

.275

KW

TL=1

64.6

30 K

W

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

LOAD

SCH

EDU

LE &

SIN

GLE

LIN

E D

IAG

RAM

OF

LT P

AN

EL

MEP

CONS

ULTA

NT:

Note

:

x x x x

R=98

.670

KW

Y=98

.670

KW

B=98

.660

KW

TL=2

96.0

00 K

W

R=98

.670

KW

Y=98

.660

KW

B=98

.670

KW

TL=2

96.0

00 K

W

PROJ

ECT

NAME

:

DRAW

ING

TITL

E:

Revis

ions

Date

NoDe

scrip

tions

Scale

:Da

te:

ELEC

TRIC

AL

LOAD

SCH

EDU

LE &

SIN

GLE

LIN

E D

IAG

RAM

OF

DB-R

(RO

OF

FLO

OR)

MEP

CONS

ULTA

NT:

Note

:

x x x x

BY

RPH

AS

E L

OA

D IN

KW

PO

INT

PE

RW

ATT

PO

INTS

NO

. OF

PO

INT

RE

FER

AN

CE

SIZ

EN

UTR

AL

PH

AS

E

RA

TM

CB

RE

F.C

KT

B3

Y3

R3

B2

Y2

R2

B1

Y1

R1

TOTA

L C

ON

NE

CTE

D L

OA

D 8

.015

KW

DS

13--

DS

18

0.51

0D

S7-

-DS

12

DS

19--

DS

24

10A

SP

DB R

EF. :

DB-

R | F

ED F

ROM

: RY

B9/M

DB-1

| LO

CATI

ON

: CAN

TEEN

(RO

OF

FLO

OR)

RE

F.M

CC

B 20A TP MCB MAIN

2.46

0TO

TAL

PH

AS

E L

OA

D3.

260

2.29

5

(rm

)S

IZE

EA

RTH

(re)

LOC

ATI

ON

2X2.

51X

2.5

DS

1--D

S6

CA

NTE

EN

60.

510

85A

mp

0.51

0

6 6

85 85

TOTA

L D

IVE

RS

IFIE

D L

OA

D (7

0%) 5

.610

KW

06W

AY (T

P) 2

0A T

P M

CB

MAI

N |

CAB

LE S

IZE

: 1X4

c,6.

0mm

2 N

YY/P

VC+1

X1c,

6.0m

m2

PVC

S/C

EC

C

CA

NTE

EN

TOIL

ETS

10A

SP

10A

SP

10A

SP

10A

SP

10A

SP

10A

SP

10A

SP

10A

SP

B4

Y4

R4

STA

IR L

OB

BY

10A

SP

10A

SP

10A

SP

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

1.5

DS

25--

DS

30

DS

31--

DS

36

DS

37--

DS

42

DS

43--

DS

48

L1--

L6+E

XF1

--E

XF2

L12-

-L19

+F1-

-F3

L20-

-L27

+F4-

-F6

L7--

L11

685

6 6

85 85

685

6 6+2

85

25/1

00

8+3

40/7

0

8+3 5

40/7

0

25

0.51

0

0.51

0

0.51

0

0.51

0

0.51

0

0.35

0

0.53

0

0.53

0

0.12

5

B5

Y5

R5

CA

NTE

EN

20A

SP

20A

SP

20A

SP

2X4.

01X

4.0

2X4.

01X

4.0

2X4.

01X

4.0

S1-

-S2

(RA

DIA

L)

S3-

-S4

(RA

DIA

L)

S5-

-S8

(RA

DIA

L)

220

0

2 4

200

200

0.40

0

0.40

0

0.80

0

B6

Y6

R6

SP

AR

E

S9-

-S12

(RA

DIA

L)

SP

AR

E

M.P

RA

YE

R R

OO

M

F.P

RA

YE

R R

OO

M

2X2.

51X

2.5

2X2.

51X

2.5

2X2.

51X

2.5

CA

NTE

EN

CA

NTE

EN

CA

NTE

EN

CA

NTE

EN

CA

NTE

EN

CA

NTE

EN

F.P

RA

YE

R R

OO

M

M.P

RA

YE

R R

OO

M

20A

SP

2X

4.0

1X4.

0

20A

SP

-

-

10A

SP

-

-

--

4 -20

0 -0.

800

-

-

TP

MCB20A

DB-R

6WA

Y

TL=

8.01

5 KW

B=2.

295

KWY=

3.26

0 KW

FED

FROM

RYB

9/M

DB-1

6WAY

, 20A

TPN

+E

COPP

ER B

US B

AR

R=2.

460

KW

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

10A

MCBSP

DS1--DS6

DS7--DS12

DS13--D18

DS19--DS24

DS25--DS30

DS31--DS36

DS37--DS42

DS43--DS48

L1--L6+EXF1--EXF2

L7--L11

L20--L27+F4--F6

L12--L19+F1--F3DL=

5.61

0 KW

(70%

)

+1X1

c,6.0

mm

2 PV

C S/

C EC

C

1X4c

,6.0

mm

2 NY

Y/PV

C

20A

MCBSP

20A

MCBSP

20A

MCBSP

S5--S8 (RADIAL)

S3--S4 (RADIAL)

S1--S2 (RADIAL)

SPARE

S9--S12 (RADIAL)

SPARE20A

MCBSP

20A

MCBSP

10A

MCBSP

1x1c

ECC

240

mm

2 BYA

/NYY

(or

10-1

2 m

m d

ia b

are

copp

er w

ire

1x4c

240 m

m2 BYA

/NYY

1x1c

ECC

240

mm

2 BYA

/NYY

(or

10-1

2 m

m d

ia b

are

copp

er w

ire

1x1c

ECC

240

mm

2 BYA

/NYY

(or

10-1

2 m

m d

ia b

are

copp

er w

ire

600

A (a

djus

tabl

e)M

CCB