Question

In which mode machine is operating, given that conductor current is in the same direction of conductor emf?

(a) Motoring

(b) Generating

(c) Can’t be determined using directions

(d) In both modes for different cycles

This question was addressed to me during a job interview.

My enquiry is from EMF and Torque Production topic in chapter Circuit Model, Emf and Torque of DC Machines

Answer 1

Correct choice is (b) Generating

The explanation is: If the conductor current is in the same direction of conductor emf then machine outputs electrical power and absorbs mechanical power. So, when mechanical power is absorbed machine is said to be in a generating mode. When conductor emf and conductor current are in opposite directions then machine is said to be in a motoring mode.