Calculation

Single Phase: LRC = (LR KVA per hp x 1000 x hp) / E

3-Phase: LRC = (LR KVA per hp x 1000 x hp) / (E x 1.732)

LRC = Locked Rotor Current in amperes

LR kVA = Value from T430.7(B)

1000 = value used to convert kVA to Volt Amps

hp = Motor Horsepower

E = Motor Voltage

LRC = (5.59 x 1000 x 30) / (460 x 1.732)

210.48 Amps

pf = Power Factor

hp = Horsepower

V = Voltage

i = Current

E = efficiency

(20 x 746) / (480V x 25 x 1.732 x 0.87) =

0.82

i = ( hp x 746 ) / ( V x E x 1.732 x pf )