7000+ DC Machines Questions and Answers Pdf - 1

Question: 1

The armature of a dc machine is laminated

(A) To reduce the inductance

(B) To reduce the mass

(C) To reduce eddy current loss

(D) To reduce the hysteresis loss

Ans: C

To reduce eddy current loss

Question: 2

A time varying flux causes an induced electromotive force. What law does this statement represent?

(A) Field form of ohm's law

(B) Lenz's law

(C) Faraday's law

(D) Ampere's law

Ans: C

Faraday's law

Question: 3

The output indicated on the name plate of any motor is always the

(A) Output power at the shaft

(B) Power drawn in kW

(C) Power drawn in kVA

(D) Gross power

Ans: A

Output power at the shaft

Question: 4

A dc series motor is best suited for driving

(A) Cranes and hoists

(B) Shear and punches

(C) Machine tools

(D) Line shafting, blowers and fans

Ans: A

Cranes and hoists

Question: 5

The variable loss in a dc shunt machine is

(A) Armature copper loss

(B) Friction and windage loss

(C) Shunt field loss

(D) Iron loss

Ans: A

Armature copper loss

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