Question

Why there is armature current is zero at no load in dc motor?

Answer 1

Hi Friend !!

Here's ur ans :-


• A shunted DC motor has field and armature windings connected in parallel to each other.

So, supply current is divided between armature and field current as,

=> I = Ia + IfI. = Ia + If

At no-load, we can safely assume 

=> Ia =0Ia=0 .

Still I=IfI=If which means the field winding draws its rated current even if the motor is at no-load.

Answer 2

Answer:

Explanation:

At no load the power taken by the motor is zero (assuming all the losses are neglected) and P = VI.

For shunted DC motor the voltage will still provide for the field. To make the power zero, armature current needs to be zero.