Question

What is the requirement of the good commutation?

(a) Brushes should be of proper grade, size and material

(b) Brushes should smoothly run in the holders

(c) Smooth, concentric commutator properly undercut

(d) Brushes should be of proper grade, size, material, run smoothly in the holders and concentric commutator properly undercut

I got this question in an international level competition.

Asked question is from Brushes and Commutator Assembly in section DC Machines of DC Machines

Answer 1

The correct answer is (d) Brushes should be of proper grade, size, material, run smoothly in the holders and concentric commutator properly undercut

Explanation: Brushes are in contact with commutator. So, for good commutation brushes must be of superior quality so that brushes will give/receive appropriate current to and from commutator. Also, the contact between brushes and commutator must be smooth for proper commutation process.