MULTIPLE CHOICE QUESTIONS
Q.1 An ideal d.c. generator is one that has .........
voltage regulation.
(A) low
(B) zero
(C) positive
(D) negative
Q.2 The ......... generator has poorest voltage
regulation.
(A) series
(B) shunt
(C) compound
(D) high
Q.3 The voltage regulation of an over compound d.c.
generator is always ..........
(A) positive
(B) negative
(C) zero
(D) high
Q.4 Most commercial compound d.c. generator are
normally supplied by the manufacturers as over compound machines because
(A) they are ideally suited for transmission of d.c.
energy to remotely-located loads
(B) degree of compounding can be adjusted by using a
divertor across series field
(C) they are more cost effective than shunt generators
(D) they have zero percent regulation.
Q.5 The speed of a d.c.
motor can be controlled by varying
(A) its flux per pole
(B) resistance of armature circuit
(C) applied voltage
(D) all of the above
Q.6 The most efficient method of increasing the speed
of a 3.75 kW d.c. shunt motor would be
the ...........method.
(A) armature control
(B) flux control
(C) Ward-Leonard
(D) tapped-field control
Q.7 Regarding Ward-Leonard system of speed control which
statement is false ?
(A) It is usually used where wide and very sensitive
speed control is required.
(B) It is used for motors having ratings from 750 kW
to 4000 kW
(C) Capital outlay involved in the system is right
since it uses two extra machines.
(D) It gives a speed range of 10 : 1 but in one
direction only.
(E) It has low overall efficiency especially at light
loads.
Q.8 In the rheostatic method of speed control for a
d.c. shunt motor, use of armature divertor makes the method
(A) less wasteful
(B) less expensive
(C) unsuitable for changing loads
(D) suitable for rapidly changing loads
Q.9 The chief advantage of Ward-Leonard system of d.c.
motor speed control is that it
(A) can be used even for small motors
(B) has high overall efficiency at all speeds
(C) gives smooth, sensitive and wide speed control
(D) uses a flywheel to reduce fluctuations in power
demand
Q.10 The flux control method using paralleling of field
coils when applied to a 4-pole series d.c. motor can give ........... speeds.
(A) 2
(B) 3
(C) 4
(D) 6
