Theory & SafetyQuestion 111 of 120
A balanced three-phase load draws 40 amperes at 480 volts with a power factor of 0.85. What is the true power?
a.Approximately 33.3 kilowatts
b.Approximately 28.3 kilowatts
c.Approximately 19.2 kilowatts
d.Approximately 16.3 kilowatts
Explanation
True power for a three-phase load is P = 1.732 x E x I x PF = 1.732 x 480 x 40 x 0.85, or about 28,270 watts. The 33.3-kilowatt answer omits the power factor and gives apparent power in kVA instead, 19.2 kilowatts leaves out the 1.732 factor, and 16.3 kilowatts omits both.
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