Question

How to avoid grooves in the commutation of DC machine with the help of brush?

(a) Brushes of opposite polarity should track each other

(b) Brushes of same polarity should track each other

(c) Brush position has no effect on the commutator grooving

(d) Brushes should not track each other

I got this question by my college professor while I was bunking the class.

My doubt is from Brushes and Commutator Assembly topic in section DC Machines of DC Machines

Answer 1

Correct option is (a) Brushes of opposite polarity should track each other

The explanation is: Brushes are located such that they are displaced 900 electrically from the axes of main poles. The two positive and two negative brushes are respectively connected in parallel for feeding the external circuit.