MCQ of D.C motor page-18

131. The resistance of the field regulator of a dc shunt motor is of the order of

A) 100 Ω
B) 10 Ω
C) 2 Ω
D) 0.5 Ω.

Ans : (A)

132. High in rush of current during a starting of a dc motor can efficiently be restricted to a safer value by increasing the …….. resistance.

A) shunt field
B) armature circuit
C) both (A) and (B)
D) none of these.

Ans : (B)

133. A 3 point starter is considered suitable for dc ….. motors.

A) series
B) shunt
C) compound
D) shunt as well as compound.

Ans : (B)

134. For efficient operation of a dc motor, the additional resistance inserted in the armature circuit should be

A) cut-out in steps
B) increased in steps
C) left in the armature circuit
D) removed immediately after start.

Ans : (A)

135. Speed control by variation of field flux results in

A) variable torque drive
B) constant torque drive
C) variable power drive
D) constant power drive.

Ans : (D)

136. In a dc shunt motor, the three point starter

A) Limits the starting current to a safer value
B) Provides over-load protection
C) Provides no-volt protection
D) All of the above.

Ans : (D)

137. The dc motor starting handle should be moved

A) very slowly in steps
B) smoothly in steps
C) quickly
D) with a jerk to final position.

Ans : (B)

138. The current drawn by a dc motor at starting is

A) very high
B) normal
C) very low
D) zero.

Ans : (A)

139. The number of poles of 8/6 stepper motor can be

A) 3
B) 4
C) 6
D) 7.

Ans : (B)

140. In Dc machines, the armature winding are placed on the rotor because of the necessity for

A) Electromechanical energy conversion
B) Generation of voltage
C) Commutation
D) Development of torque.

Ans : (C)

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