Useful Electrical Formulas and Charts

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Formulas and Charts

TO OBTAIN	SINGLE PHASE *	THREE PHASE *
Kilowatts	V x I x pf 1000	1.732 x V x I x pf 1000
kV-A	V x I 1000	1.732 x V x I 1000
Horsepower required when generator kW unknown (if generator efficiency is unknown, use 0.93)	kW 0.716 x Efficiency (Generator)	kW 0.746 x Efficiency (Generator)
kW input when motor hp known (if motor efficiency unknown, use 0.85 x hp)	hp x 0.746 Efficiency (Motor)	hp x 0.746 Efficiency (Motor)
Amperes when motor hp known	hp x 0.746 V x ph x Efficiency	hp x 0.746 1.732 x V x pf x Efficiency
Amperes when kW known	kW x 1000 V x pf	kW x 1000 1.732 x V x pf
Amperes when kV-A known	kV-A x 1000 V	kV-A x 1000 1.732 x V
* Alternating Current

80% POWER FACTOR
kW	120 V	208 V	240 V	480 V	600 V	2400 V	4160 V
10	83 A	35 A	42 A	15 A	12 A	3 A	1.7 A
20	167 A	69 A	83 A	30 A	24 A	6 A	3.5 A
30	250 A	104 A	125 A	45 A	36 A	9 A	5.2 A
40	333 A	139 A	167 A	60 A	48 A	12 A	6.9 A
50	417 A	173 A	208 A	75 A	60 A	15 A	8.7 A
75	625 A	260 A	313 A	113 A	90 A	22.6 A	13 A
100	833 A	347 A	417 A	150 A	120 A	30.1 A	17.3 A
125	1042 A	434 A	521 A	188 A	150 A	37.6 A	21.7 A
175	1458 A	607 A	729 A	263 A	210 A	52.6 A	30.4 A
225	1875 A	781 A	938 A	338 A	271 A	67.7 A	39 A
275	2292 A	954 A	1146 A	413 A	331 A	82.7 A	47.7 A
300	2500 A	1041 A	1250 A	451 A	361 A	90.2 A	52 A
350	2917 A	1214 A	1458 A	526 A	421 A	105 A	61 A
400	3333 A	1388 A	1667 A	601 A	481 A	120 A	69 A
500	4167 A	1735 A	2083 A	752 A	601 A	150 A	87 A
600	5000 A	2082A	2500 A	902 A	722 A	180 A	104 A
750	6250 A	2602 A	3125 A	1128 A	902 A	226 A	130 A
900	7500 A	3123 A	3750 A	1353 A	1083 A	271 A	156 A
1250	10417 A	4337 A	5208 A	1879 A	1504 A	376 A	217 A
1500	12500 A	5205 A	6250 A	2255 A	1804 A	451 A	260 A
1750	14583 A	6072 A	7292 A	2631 A	2105 A	526 A	304 A
2000	16667 A	6940 A	8333 A	3007 A	2406 A	601 A	347 A

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Cable Size	80-90°C	110°C
2/0	285 A	330 A
4/0	385 A	445 A
313 mcm	480 A	555 A
500 mcm	660 A	765 A
750 mcm	845A	980 A