Simple Multiple Choice ?...Please let me know if I'm right, Thanks!

Thread Starter


Joined Jun 26, 2010
a single phase 1HP motor consumes 9A at supply voltage of 123V at 60Hz at a power factor of 78% while driving a fan. Which of the following statements is true?

a) The motor is overloaded
b) The motor is not overloaded
c) The motor is operating at 50% efficiency
d) The speed of the motor is 3600 rpm

I think the answer is A. I don't think it can be C because the numbers I came out with suggest it's operating above it's 1HP capacity? I don't think it can be D because there's no mention of the # of poles so I don't even know how you would calculate the rpm...

Please let me know if I'm right or help steer me in the right direction, Thanks!


Joined Mar 6, 2009
I'd agree with answer (a) for the following reason ....


At 123V supply and pf=0.78


So at Iload=9A, the rated current is being exceeded which suggests an overload condition.