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General info

TECHNICAL 
Main Fuse and Supply Cable Cross Section for Three Phase Capacitors
Rating Rated Voltage 400 VAC Rated Voltage 525 VAC
Kvar Rated Fuse rating Supply cable Rated Fuse rating Supply cable
Current Delay type Cross section Current Delay type Cross section
AMPS AMPS mm²   AMPS AMPS mm²
2 2.88 10 1.5
2.5 3.60 10 1.5 2.74 10 1.5
3 4.32 10 1.5 3.30 10 1.5
4 5.76 10 1.5 4.40 10 1.5
5 7.20 16 2.5 5.50 10 1.5
6 8.64 16 2.5 6.60 16 2.5
7.5 10.80 20 2.5 8.30 16 2.5
10 14.40 25 4 11.00 20 2.5
12.5 18.00 36 6 13.70 25 4
15 21.60 50 10 16.50 36 6
16.7 24.10 50 10 18.40 36 6
20 28.80 50 10 22.00 50 10
25 36.00 63 16 27.40 50 10
30 43.20 80 25 33.00 63 16
35 50.50 100 35 38.50 80 25
40 57.60 100 35 44.00 80 25
50 72.00 125 50 55.00 100 35
60 86.40 160 50 66.00 125 50
Current Rating for Single Rectangular Copper Busbar in Still  Air
Main Fuse and Supply Cable Cross Section  for Control Sytem 400 VAC.
Busbar Mass Approximate
size A.C.
Bank Supply Cable Fuse rating
rating Cross Section Delay type  mm x mm  Kg / m Still air Amp
25 x 3.15 0.703 300
Kvar mm² Amps 25 x 6,3 1,406 400
31,5 x 6,3 1,772 500
10   4 x 4 25 31,5 x 10 2,812 600
12.5   4 x 6 36 40 x 6,3 1,406 600
15-20   4 x 10 50 40 x 10 3,572 800
25-30   4 x 16 63 40 x 12.5 4,465 900
35-40   3 x 25 + 16 earth / wire 80 50 x 6,3 2,902 800
50   3 x 35 + 16 earth / wire 100 50 x 10 4,456 1000
60   3 x 50 + 25 earth / wire 125 50 x 12,5 5,581 1100
75   3 x 70 + 35 earth / wire 160 80 x 6.3 4,500 1100
90-100   3 x 95 + 50 earth / wire 200 80 x 10 7,144 1400
120-125   3 x 120 + 70 earth / wire 250 80 x 12,5 8,93 1600
150   3 x 185 + 95 earth / wire 315 80 x 15,8 11.288 1800
175-200   Two Cables   3 x 95 + 95 earth / wire 400 100 x 6,3 5,626 1400
210-250   Two Cables   3 x 120 + 95 earth / wire 500 100 x 10 8,930 1600
270-300   Two Cables   3 x 185 + 95 earth / wire 630 100 x 12,5 11,163 2000
101 x 15,8 14,250 2500
FINDING THE REQUIRED CAPACITOR RATINGFor Individual Correction of Motors USEFUL 3 PHASE FORMULAE
The Capacitor Rating should correspond approximately to the apparent power of the motor on No- Load . KW=  KVA  x Power Factor
The rating given in the table below are for guidance purposes and based on 1500 r.p.m. motors.  The tabulated values can be increased by 5 % for 1000 r.p.m. motors and by 15 % for 750 r.p.m. motors. KW= Line Amps x Line Volts x 1.73 x Power Factor
1000
Motor Rating KW Motor Rating  H.P. Capacitor Rating KVAr
KW= HP x 746
1000 x Efficiency
KVA= KW
1 to 1.9 1.0 to 2.6 0.5 Power Factor
2 to 2.9 2.7 to 4.0 1
3 to 3.9 4.1 to 5.3 1.5 KVA= Line Amps x Line Volts x 1.73
4 to 4.9 5.4 to 6.7 2 1000
5 to 5.9 6.8 to 8.0 2.5
6 to 7.9 8.1 to 10.7 3 KVA= HP x 746
8 to 10.9 10.8 to 14.8 4 1000 x Efficiency x Power Factor
11 to 13.9 14.9 to 18.9 5
14 to 17.9 19.0 to 24.4 6 Line Amps = KW x 1000
18 to 21.9 24.5 to 29.8 7.5 Line Volts x 1.73 x Power Factor
22 to 29.9 29.9 to 40.9 10
30 to 39.9 41.0 to 54.0 Approx. 40 % of motor Line Amps = KVA x 1000
From 40… From 54.1 … Approx. 35 % of motor Line Volts x 1.73
Line Amps = KVA x 1000
Line Volts x 1.73 x Power Factor x Efficiency
Capacitor Rating Required for individual Correction of Transformers FORMULAE TO CALCULATE MASS (Kg)FOR RECTANGULAR COPPER BUSBAR WIDTH x THICKNESS x 0.00893=KG
The capacitor is intended only to cover the no-load reactive VA  of the transformer.  The capacitor rating is roughly 3 % to 5 % of the transformer rating . In case of doubt please consult your supply undertaking.
Transformer Rating              KVA Capacitor Rating for Voltages of  COPPER BUSBAR TORQUESETTINGS FOR MCC`s  or  MDB`sCOPPER CONNECTION TORQUE SETTINGS
11 KV 22 KV
KVAr KVAr
250 10 15 Bolt Torque 
400 15 20 Size    Nm
630 20 30
800 25 40 M6 11
1000 30 50 M8 25
1250 35 60 M10 35
1600 50 80 M12 45
2000 60 100 M16 91