Motor Amperage Question / Answer

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M achew

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Location
Colorado
Occupation
Electrician Apprentice
Happy late Turkey Day! Did my first 100 question practice test without the answers after you chose. I completed it in 2.5 hrs and 91%. I'll do another in the morning and then some extra reading. Keep in mind I have seen many of these questions before. I will slow way down for the actual test and use all of the time to be sure I pass.
 
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Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
M achew said:
How many amps does a 3-hp, 240v, 3-Phase motor draw if the motor has 90% efficiancy & a power factor of 95%?

I started with looking up the FLA = 9.6 in table 430.250

Then 9.6 / 75% = RLA (7.2)

Next 7.2 x 90% x 95% = 6.156 amps

The correct answer was 6.3

I know I'm close, but where am I off?
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Pardon my ignorance, but what is the 75% for and I believe that would be times not divided by 75%
 
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