No-Load Current of Electric Motors

No way to know. No two motors are alike, and No-Load current has a lot to do with the construction of the motor. GENERALLY, the no load current is between 20 and 40% of the motor Full Load Current, but like any rule, there are exceptions. So it could really be 10 - 60% as well.

No equation. The best way to get the data from the vendor or simply test by yourself if you have the motor with you (apply full voltage to the motor without load and measure the current with a clip-on meter - very simple).

Though the rule of thumb is that the 'no load current' is 1/3 of 'full load current' but it is with many exceptions.

- MS

Always remember that head pressure is directly propotional to the length and speed of stroke. I'm sure that you've been implementing that equation for some time now.

The speed of the motor also have an influence on the no load current.

The slower the motors operating speed (8 pole motor), the higher the no load current will be compared to a motor with the same kW rating, operating at higher speed (2 pole motor).

Good answers from others - this old thread may help as well.

You have to know other variables to know it. Here you need to measure or calculate (rather difficult) no load impedance of a motor,

No load current is = Voltage/ No load impedance(z).

So can you calculate no load impedance(z)?

Dear Friend,

The No-Load Current and locii of current of the motor from no-load to full load is governed by the CIRCLE DIAGRAM.

Hence you have to construct the circle diagram for the Motor. How to construct the circle diagram is very well explained in the Eectrical Technology book. Pl. refer and you can identify the same.

DHAYANANDHAN.S