Complex Analysis Calculations for Electrical Design Engineers

220 30 20

220 20 10

220 50 6600

0.809930407

6600

4400

7023.573298

4467.877092

55

4003.672577

0.939692621

775.8387151

-42.29986201

0.984807753

4779.511292

35.91086744

4138.443734

775.8387151

6600

4400

Lower limit kV -10% 360 198 99 29.7

Voltage kV 0% 400 220 110 33

Higher limit kV 10% 440 242 121 36.3

9.9 0.3735 0.216 0.099

11 0.415 0.24 0.11

12.1 0.4565 0.264 0.121

Rated Voltage 230 V

101.54

Actual Power 100 kW 103.11

Phase shift 10 Deg

Calc. Current 441.49 A

Obtained App. Pwr 101.54 kVA

Obtained React. Pwr 17.63 kVAR

Rated Voltage 415 V

101.54

Actual Power 100 kW 103.11

Phase shift 10 Deg

Calc. Current 141.27 A



1φ System

3φ System

kVAR

17.63

17.63 kW

100.00

101.54 Cos (pi) 0.98 0.98

Tan (pi) 0.17 0.18

Sin (pi) 0.17 0.17

kVAR

17.63

17.63 kW

100.00

101.54 Cos (pi) 0.98 0.98

Tan (pi) 0.17 0.18

Sin (pi) 0.17 0.17

kVA

kVA

Rated Voltage 415 V

-532.09

Actual Power 500 kW -566.24

Phase shift 20 Deg

Calc. Current 740 A

Change in Power -500 kW

Calc. Current -740 A

Obtained App. Pwr -532.09 kVA

Obtained React. Pwr -181.99 kVAR

Rated Voltage 415 V

1252.14

Generated Power 1000 kW 1567.84

Phase shift 37 Deg

Calc. Current 1742 A



Conventional System

Solar System

kVAR

-181.99

-181.99 kW

-500.00

-532.09 Cos (pi) 0.94 0.94

Tan (pi) 0.34 0.36

Sin (pi) 0.32 0.34

kVAR

753.55

753.55 kW

1000.00

1252.14 Cos (pi) 0.80 0.80

Tan (pi) 0.60 0.75

Sin (pi) 0.48 0.60

kVA

kVA

V Z I

230 5% 4600 kV

Lowest

System

Voltage (kV)

415 5% 8300 750

3300 5% 66000 400 360

6600 5% 132000 220 200

11000 5% 220000 132 120

22000 5% 440000 66

33000 5% 660000 33

66000 5% 1320000 11

110000 5% 2200000

132000 5% 2640000

220000 5% 4400000

400000 5% 8000000

765000 5% 15300000

Highest

System

Voltage (kV)

Variation of

Voltage (+-

%)

S/s Area

(Acre)

S/s Size

(m x m)Capacity (kVA) Bus Bar Scheme

800 Breaker and Half

420 Breaker and Half

245 12 -16 200 x 200

Double bus scheme

or Double main and

Transfer bus scheme

145 6 - 8 150 x 200 Double bus scheme

72.5 2 - 4 80 x 120

36 10

12 10

Ampacity of Bus bar

(A)

Suspension

string Discs

Tension

string Discs

S/s Earth

Resistance

(Ohm)

Creepage

Distance

(mm)

Specific

Creepage

Distance

(mm/kV)

Current for CTs (A)

36 2 x 36 0.5 12600 15.75

3200 25 2 x 25 0.5 8050 19.16 800, 1250

3200 13 14 0.5 4900 20 800, 1250, 1600, 2000

1600 9 10 0.5 3150 21.7 800, 1250, 2000

1 1750 24.3 400, 800, 1250, 2000

3 4 2 1050 29.17

3 4 5 350 29.17

Current for

CTs (A)

800, 1250, 1600, 2000

kV 750 400 220

Lowest System Voltage (kV) 360 200

Highest System Voltage (kV) 800 420 245

Variation of Voltage (+- %)

S/s Area (Acre) 12 -16

S/s Size (m x m) 200 x 200

Standard Bay Width (m) 27 17

Capacity (kVA)

Bus Bar Scheme Breaker and Half Breaker and Half

Double bus scheme or

Double main and

Transfer bus scheme

Bus Bar Material Moose (Quadraple)Moose (Single / Twin /

Quadraple)

Ampacity of Bus bar (A) 3200 3200

Suspension string Discs 36 25 13

Tension string Discs 2 x 36 2 x 25 14

S/s Earth Resistance (Ohm) 0.5 0.5 0.5

Full Wave Impulse Withstand Voltage

(1.2 / 50 micro sec.) kVp

1425 kVp for

substation 1550 kVp

for lines

900 - 1050

Switching impulse Withstand Voltage

(250 / 2500 ms) kVp1050 -

One minute Power Freq. withstand

voltage (rms) dry & wet (kV)

630 kV for substation

680 kVp for lines460

Corona Extinction Voltage (kV) 320 156

Max. Radio Interference Votage (RIV)

Betn 0.5 to 2 MHz at 267, 156 & 105

kVrms for 400, 220 & 132 kV

1000 micro volt 1000 micro volt

Min. Creepage Distance (mm) 12600 8050 4900

Total Creepage Distance (mm) 3800

Specific Creepage Distance (mm/kV) 15.75 19.16 20

Current for CTs (A) 800, 1250 800, 1250, 1600, 2000

Min. Clearances:

Phase to Phase (mm)

4200 mm for Rod

Type Conductor /

4000 mm for Cond to

Cond

2100

Phase to Earth (Sub station) (mm) 3500 2100

Sectional clearance (mm) 6500 5000

Equipment live terminal elevation (m) 8 4.9 - 5.5

Take-Off line elevation (m) 23 15 - 18.5

Live part to Tower Body under nil swing 3050 2130

Rated Short Ckt. Current for 1 Sec. (kA) 40 40

System Neutral EarthingEffectively

EarthedEffectively Earthed Effectively Earthed

Max. rated break time of CB's (ms) 40 60

Protection Schemes

Main I: Non Switched

or Numerical

Distance Scheme,

Main II: Non

Switched or

Numerical Distance

Scheme

Main I: Non Switched

Distance Scheme (Fed

from Bus PTs), Main II:

Switched Distance

Scheme (Fed from line

CVTs) with a changeover

facility from Bus PT to

line CVT and vice-versa

Normal Span of Line (m) 400 380 & 350

Min. Ground clearance of bottom most

conductor (m)8.84 7

Min. midspan clearance betn ground

wire & top most power conductor (m)9 8.5

132 66 33 11 0.415

120

145 72.5 36 12 0.457

10 10 10

6 - 8 2 - 4 1 1 0.50

150 x 200 80 x 120

12.2 7.6 4.7 4.7 -

Double bus scheme

Zebra (Single / Twin) Zebra (Single / Twin) Zebra (Single / Twin)

1600

9 3 3 1

10 4 4 2

0.5 1 2 5 10

530 - 650 325 170 75 6

- - - - -

275 80 28 3

105

1000 micro volt

3150 1750 1050 350 75

2250 760

21.7 24.3 29.17 29.17 29.17

800, 1250, 2000 400, 800, 1250, 2000

1600 750 350 127 19

1300 630 320 76.2 15.8

4000 3000 2800 2600300 (outdoor) or

50 (indoor)

3.7 - 5 4 2.8 - 4 2.8 - 4

12 - 12.5 9.5 6.5 - 8.5 6.5 - 8.5

1530 - -

31.5 25 25 10

Effectively Earthed Effectively Earthed Effectively Earthed Effectively EarthedEffectively

Earthed

100 3000 3000 3000

Main Protection:

Switched Distance

Scheme (Fed from Bus

PTs), Backup

Protection: 3 nos

Directional IDMT O/L

Relays & 1 nos

Directional IDMT E/L

Relay

Distance, O/L & E/LNon Directional IDMT

3 O/L and 1 E/L Relay

Non Directional IDMT

2 O/L and 1 E/L RelayO/C & E/L

320

6.1

6.1

1 INPUT DATA

Feeder Load KVA

Rated Voltage kV

Length of the cable m

Allowable Voltage Drop %

Power factor

Total number of runs

Final temperature °C

Initial temperature °C

Duration of short circuit in sec. sec

2 FULL LOAD CURRENT

From Vendor data sheet, 630 Sq.mm 1C, XLPE AL cable is selected

AC resistance of the cable at 90°C = Ω / km

Reactance of the cable at 50Hz = Ω / kmRated current for selected cable = A

Factor for Ambient Temperature, 400C =

Factor for variation of Ground Temperature, 350C =

Factor for grouping the cables =

Factor for variation in depth of laying the cable =

Factor for Thermal Resistivity (1.8 km/W) =

Net current derating factor =

So, Current carrying capacity of selected cable = A

3 VOLTAGE DROP

t = 1

0.065

0.084

= 250Фi = 90

IFL =P (kVA)√3 x kV

=630

P = 630

V = 0.32

= 100

R

X

=Sin φ

= 5

=

L

n

0.5543= 1136.66

0.8

Cos φ =

1228

1.732 x IFL

Vdrop = x

814

1

1.2

0.81

0.97

0.99

0.14

2Фf

A

Vdrop = 7.50 V

n

1968.69

x 100

(R cosφ + X sinφ) x L

0.754

x 100320

Vdrop = x 0.0001

=Vdrop

V% Vdrop

1002

x

=7.50

The selected cable is in Permissible Voltage Drop

4 SHORT CIRCUIT CURRENT RATING OF CABLE Isc

(β + Фf)

(β + Фi)

5 REVERSE CALCULATION FOR C.S.A OF CABLE

6 EARTH FAULT CURRENT

A

Ief =134.4

1

Ief = 134.4

Sq.mm

Ief =A x K

√t

C.S.A =57960.00

92

C.S.A = 630

C.S.A =Isc x √t

Isc = 57960 A

Isc =57960

K

478

318ln

1

Isc =A x K x є

√tln

% Vdrop = 2.35 %

Cells for Input the data

Cells for Result

3 Ph % VD (1.732 x Ifl x Z x L) x 100/(n x V)

1 Ph % VD (2 x Ifl x Z x L) x 100/(n x V)

HV % VD (3 x Ifl x Z x L) x 100/(n x V)

Insulation Material Conductor Material Operating Temp.

PVC Copper 70

PVC Aluminum 70

XLPE Copper 90

XLPE Aluminum 90

β for Copper 234β for Aluminum 228

β for Steel 202

є 1

Material K Factor

Steel Wire Armour 42

Lead Sheath 24Copper Tape 143

Aluminm Wire Armour 76

Short Ckt Temp. K Factor K Factor

160 115

160 76

250 143 226

250 92 148

Complex Analysis Calculations for Electrical Design Engineers

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