Efficiency & Testing of DC Machines - GATE EE Electrical Free MCQ Test

A dc motor is connected in the short-shunt configuration, but the series and the shunt windings get interchanged by mistake and the motor is connected to the rated voltage,

 The main concern before doing hopkinson’s test for finding efficiency is

 Retardation test on DC shunt motor is used for finding _______

The quantities needed to complete retardation test are/is

 ______ test is used for determining the efficiency of a traction motor

 If the field current and armature current are reversed, then

 Mark the possible causes of overheating of commutator in a DC machine.

In the hopkinson’s test on two DC machines. Machine A has field current of 1.4A and B has field current of 1.3A. Which machine acts as motor?

In the Hopkinson’s test on two DC machines. Machine A has field current of 1.4A and B has field current of 1.3A. Which machine acts as generator?

 Hopkinson’s test is also called regenerative test due to

The most appropriate relation to find efficiency of the generator

The efficiency in the swineburne’s test can be found.

The possible assumption is/are made while doing swineburne’s test
(i) mechanical loss constant
(ii) Armature reaction neglected
(iii) Increase

Swineburne’s test is applicable to those machines in which flux is practically _______

Similarity between Hopkinonson’s and field’s test is that