Question

A DC motor operates with 220V mains. Initiallyit draws a current of 20A. The resistance of starteris 61. When the motor runs at its full speed itconsumes 500 W power. Find the current drawn
by it.
(1) 5A (2) 10A (3) 15A (4) 20A​

Answer 1

The current will be 5 A.

Explanation:

Using the initial current first we will find back emf, we know that:

I = (V - E) / R

So,

E = V – IR

E = 220 – 20*6

E = 100 V

As the power is 500, using formula given below,

P = IE  

I = P/E

I = 500/100

I = 5 A