Configuration of an Induction motor


Joined Jun 7, 2009
Dear All,

Is there a test to find out which configuration an induction motor is in; i.e. star or delta?

We have an induction motor of which I am told its in delta configuration nut I have doubts and am wondering if there is a way I can verify this?

the manufacturer knows for sure and may even stamp it on the nameplate.

There are some general differences in operation that can alude to which winding is employed;

Star windings typically provide better low load efficiencies. At no load, a star will typically draw less than 15% FLA. It's delta counter part will draw 30+% FLA. As such, star wound is often employed where the motor predominately runs unloaded, or less than approx 30% rated load. On the other end of the scale, delta motors have better speed regulation at load, and are most often used on continous loads, or frequent loads exceeding approx 40% of rated power.

This can be used to advantage in a star/delta switching arrangements to maximize effeciencies based on load, for line fed motors.

Turn your motor on and measure no load draw, then compare it to nameplate FLA. Of course, if you have no nameplate or any information, you don't know the voltage, it's HP rating, etc, so why even ask if it's wye or delta?