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EMF & Torque Equation of DC Machines. Starter Quiz

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Question 1

A 4 pole, 60 kW, DC machine operating at 1000 rpm has a generated emf of 150 V, If the speed is reduced to 80% of its original value and the pole flux is tripled, then induced emf will be.

Question 2

In a 4-pole DC generator, the ratio of induced emf in lap winding and wave winding respectively.

Question 3

For DC machine if flux per pole is 0.03612 Wb, total conductors are 432, speed in rpm 900 and consists of 6 poles induced emf for wave connection is ______Volts.

Question 4

Consider the following statements regarding commutation in DC machines:

1) In a dc machine the ripples in emf generated are reduced by employing commutator with large number of segments.

2) In dc machine the number of commutator segments is equal to armature turns.

3) The purpose of commutator in dc generator is to convert dc into ac.

Which of the above statements is/are NOT correct?

Question 5

The speed of a dc motor is related to the back emf and flux in the following ways:

Question 6

A 10-pole lap wound DC armature has a total of 200 conductors, each with a current carrying capacity of 10 A. The average induced emf per conductor is 10 V. The power rating of the DC machine is

Question 7

A 10 kW, 6 pole, DC generator at 1500 rpm, develop 200 V EMF, if:

(i) Average flux density = 0.9 T

(ii) Length of armature = 0.25 m

(iii) Diameter of armature = 0.2 m

If armature is wave connected, total armature conductors are:

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