A three-phase alternator operates at 450 volts with a 0.8 power factor. If the ammeter indicates 250 amperes, what should be the kW meter reading?
⢠Three-phase power formula for real power (kW) in a balanced system ⢠Relationship between line voltage, line current, and power factor ⢠How to convert from kVA to kW using power factor
⢠Start by recalling the standard formula for three-phase real power using line voltage, line current, and power factor. Which constant (like â3) belongs in that formula? ⢠Calculate the apparent power (in kVA) first using voltage and current. Then ask: how does power factor change kVA into kW? ⢠Once you have the kW value from your formula, compare it to the choices. Does it match one of them closely without extra rounding steps?
⢠Be sure you are using line values (450 V and 250 A) correctly in the threeâphase formula, not singleâphase formulas ⢠Confirm you are multiplying by power factor (0.8) at the correct stepâafter you find apparent power, not before ⢠Double-check your calculator work for the square root of 3 (â1.732) and make sure units end up in kW rather than W or kVA
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