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AE-JE Foundation EE : Electrical Machines Quiz -4

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Question 1

A 220V dc compound generator connected in long-shunt mode has the following parameters: Ra = 0.1Ω, Rsh = 80Ω, Rseries = 0.05Ω. For a load of 150A at rated terminal voltage, the induced emf of the generator should nearly by

Question 2

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:

Question 3

Consider an 8-pole, 200 V, lap wound, DC shunt generator. Its armature have 100 coils of 8 turns. Its field winding resistance is 100 Ω. Each conductor resistance is 0.025 Ω. At maximum efficiency, current is _____, if total core and mechanical losses are 1250 Watts.

Question 4

In an unloaded shunt generator, when switch is closed, a small filed current is produced which leads to generation of still larger voltage due to addition of

Question 5

The function of interpoles in DC machine is to:

Question 6

If a DC compound machine connected as a generator is run as a motor, the series field connections must be in ______ , as the armature current _________.

Question 7

Which type of DC generator is most suitable for arc welding application?

Question 8

A lap wound DC machine having 4-poles has 720 armature conductors. Its field winding is excited from a Dc source to create an air-gap flux of 32 mWb/pole. The generator is run from a prime mover at 1500 rpm and supplies a current of 100 A to an electric load. Calculate the electromagnetic power developed in the machine?

Question 9

A DC shunt generator having a shunt field resistance of 100 Ω is running normally at 1000 RPM. The critical resistance of the machine is 200 Ω. Due to some reason, the generator just failed to operate, the speed of the prime mover becomes

Question 10

A commutator in a d.c. machine
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Oct 31AE & JE Exams