đ Key Concepts
⢠Use the emergency diesel generator rating shown on the oneâline diagram (kW and voltage).
⢠Recall the 3âphase power relationship between kW, kVA, volts, amps, and power factor.
⢠Convert from real power (kW) at a given power factor of 0.9 to line current at 480 VAC, 3âphase.
đ Think About
⢠From the illustration, what is the kW rating and voltage of the emergency generator? Is it singleâphase or 3âphase?
⢠Once you find apparent power in kVA using the power factor, how do you relate kVA, lineâtoâline voltage, and line current in a 3âphase system?
⢠After computing the current, which answer choice is numerically the closest to your calculated value?
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Before You Answer
⢠Be sure you are using the emergency generatorâs rating, not one of the shipâs service diesel generators.
⢠Use the correct 3âphase formula: include â3 and use lineâtoâline voltage (480 V), not phase voltage.
⢠Carry units carefully (kW â kVA â A) so the final value is in amperes and is reasonable for a 500 kW, 480 V, 3âphase machine.