Table fans do not run on UPS.?

Question

Hi,

I am trying to use a computer UPS for running a table fan, but it does not run. I can run TV, Lights on that UPS but when i plug in the table fan it does not run.
Any reason / solution for it? please advise The fan is of 45 Watts and UPS of 500 watts. The fan runs properly in raw power.

Thanks - Amit

Answer 1

I suspect that the problem is the inrush current of the fan, which can be 8 to 20 times the normal run current (for the duration of 1 cycles or so).
The starting current can also be 6 to 8 times normal run current until the motor reaches about 90% of it's operating speed.
This means that , even though the fan is rated at 45watt, to start the thing takes 360watts, with a momentary spike of 900watts to initially magnetize the rotor. I'll bet if you read the instruction manual, it would specifically prohibit this application.
Now the question is, why would you want to? Fans are not a mission critical application, they are a convenience.