MCQs of DC Machines (Electrical Machine - I - 3140913)

Showing 81 to 90 out of 167 Questions

81.

A triangular mmf wave is produced in the air gap of an electric machine. Such a wave is produced by

(a)	the rotor of a synchronous machine
(b)	the stator of an induction machine
(c)	the rotor of a dc machine
(d)	the stator of a dc machine

82.

A commutator in dc machine provide __________ rectification.

83.

In dc machine armature windings are placed on rotor because of the necessity for

(a)	electromechanical energy conversion
(b)	generation of voltage
(c)	commutation
(d)	development of torque

84.

Generators work on the principle of production of

(a)	statically induced emf
(b)	dynamically induced emf
(c)	dynamically and statically induced emf
(d)	none of the above

85.

Counter emf of a DC motor

(a)	exceeds supply voltage
(b)	aids applied voltage
(c)	helps in energy conversion
(d)	regulates its armature voltage

86.

Why the armature of DC machine is laminated.

(a)	to reduce the mass
(b)	to reduce the inductor
(c)	to reduce the eddy current loss
(d)	to reduce the hysteresis loss

87.

Width of a carbon brush should be equal to

(a)	less than the width of the commutator segment
(b)	the width of the 1 to 2 commutator segment
(c)	the width of the 2 to 3 commutator segment
(d)	the width more than 3 commutator segment

88.

Speed of DC motor can be controlled by varying

(a)	applied voltage
(b)	its flux per pole
(c)	the resistance of armature culture
(d)	all of these

89.

E_b/V_t ratio of a DC motor is an indication of

90.

In DC shunt motor if the load is increased, the speed

Showing 81 to 90 out of 167 Questions