1

Phase Size of conductor Equi- Equi- Resis React- Percentage Regulationto in mm valent valent tance ance constant for lagging P.F.Phase alum- spacing at inVoltage inium in 40 o c in Ohms/ 0.8 0.9 Unity area in meter Ohms/ Km

Sq.mm km

415 V Gnat 7/2.21 mm AAC 16 0.483 1.1566 0.3330 65.33000 68.90000 67.08000

415 V Ant 7/3.31 mm AAC 30 0.483 0.5879 0.3115 38.16000 38.57000 34.14000

11 KV Squirel 7/2.11 mm ACSR 20 0.914 1.4750 0.3900 0.11690 0.12370 0.12190

11 KV Weasel 7/2.59 mm ACSR 30 0.914 0.9770 0.3820 0.08400 0.08710 0.08150

11 KV Mink 7/3.66 mm ACSR 40 0.914 0.4900 0.3650 0.05049 0.04958 0.04144

22 KV Weasel 7/2.59 mm ACSR 30 1.066 0.9770 0.3920 0.02120 0.02180 0.02040

22 KV Mink 7/3.66 mm ACSR 40 1.066 0.4900 0.3800 0.01290 0.01260 0.01020

33 KV Weasel 7/2.59 mm ACSR 30 1.371 0.9770 0.4085 0.00950 0.00980 0.00910

33 KV Mink 7/3.66 mm ACSR 40 1.371 0.4900 0.3980 0.00580 0.00570 0.00450

REGULATION CONSTANTS FOR OVERHEAD LINESThree Phases 50 Hz per 100 KVA per Km

FORMULA FOR % V.R. CALCULATION FOR 11 KV , 22 KV & 33 KV LINES

[ Es - Er ]% Voltage regulation = x 100 Es

Where,Es = Sending end voltageEr = Receiveing end voltageEr = Es - [ IR Cos Ø + IX Sin Ø]

S/S

500 KVA 500 KVA

Percentage Voltage regulation at B for 11 KV feeder of Squirrel Conductor,kva km between B & A = 500 x 2 = 1000kva km between A & SS = 1000 x 1 = 1000Total kva km = 1000 + 1000 = 2000

Constant from table% Regulation = Total kva km x

100

2000 x 0.1211= = 2.422 % ( This should not exceed ± 6% for L.T. & ± 12% for H.T.) 100

2

FORMULA FOR CALCULATION FOR LINE LOSSES AS PER REC STANDARD

11 KV Line 33 KV Line

Average Energy Loss in feeder Average Energy Loss in feeder in KWH

0.105 x L x R x P 2 x L.L.F. = Peak power Loss x LLF x 8760 =

2 x LDF x (D.F.) 2

R = Resistance of Conductor per Km 3 x I 2 RL = Length of Line in Km Peak Power Loss =P = Total conducted load in KVA 1000LLF = Loss load factor WhereLF = Load factor of system R = Resistance of conductor per Km.D.F. = Diversity Factor I = Max current in the line.L.D.F. = Load distribution factorL.L.F. = 0.8 x ( L.F.) 2 + 0.2 x (L.F.)

LINE CLEARANCES

The minimum clearances shall be in accordance with Indian Electricity Rules, 1956 and are given inTable I.

Table - I, Minimum Clearance ( Values in Meters )

Voltage Category Low & Medium Voltage High Voltage Extra High Voltage (IE Rules,1956) Nominal System - Low Upto Upto 66 KV 132 KV 220 KV 400 KV ±500 KV 800 KV Voltage Clearance 11 KV 33 KV HVDC

1) Clearance to Ground (a) Across Street 5.8 6.1 6.1 6.1 6.1 7.0 8.80 12.50 12.40 (b) Along Street 5.5 5.6 5.8 6.1 6.1 7.0 8.80 12.50 12.40 (c) Other areas Bore Cond. 4.6 4.6 5.2 5.5 6.1 7.0 8.80 12.50 12.40 (d) Other areas Insu. cond. 4.0 4.0 - - - - - - -

2) Clearance to Buildings (a) Vertical (*) - from 2.5 3.7 3.7 4.0 4.6 5.5 7.30 11.59 10.50 higher object $ (b) Horizantal (+) - from 1.129 1.219 2.0 2.3 2.9 3.80 5.6 10.98 9.20 nearest point.

3) Clearance Between Line crossing each other.

Voltage of 1 st Line Voltage of 2 nd Line

250V to 66KV 100 KV 132 KV 220 KV 400 KV ± 500KV 800 KV HVDC

250 V to 66 KV 2.44 2.75 3.05 4.58 5.49 6.86 7.94 100 KV 2.75 2.75 3.05 4.58 5.49 6.86 7.94 132 KV 3.05 3.05 3.05 4.58 5.49 6.86 7.94 220 KV 4.58 4.58 4.58 4.58 5.49 6.86 7.94 400 KV 5.49 5.49 5.49 5.49 5.49 6.86 7.94 + 500 KV HVDC 6.86 6.86 6.86 6.86 6.86 6.86 7.94 800 KV 7.94 7.94 7.94 7.94 7.94 7.94 7.94