Electrical Machine - I (3140913) MCQs

MCQs of DC Machines

Showing 1 to 10 out of 167 Questions
1 2 3 4 5 6
1.
If field current is decreased in a shunt dc motor, the speed of the motor
(a) remains the same
(b) increases
(c) decreases
(d) none of the above
Answer:

Option (b)

2.
What is the mechanical power developed by a DC series motor is maximum?
(a) Back emf is equal to half the applied voltage
(b) Back emf is equal to the applied voltage
(c) Back emf is equal to zero
(d) None of above
Answer:

Option (a)

3.
In the Ward-Leonard system, the lower limit of the speed imposed by
(a) Field resistance
(b) Armature resistance
(c) Residual magnetism of the generator
(d) None of the above
Answer:

Option (c)

4.
Ward-Leonard control is basically a ___________ control method.
(a) Field control
(b) Armature resistance control
(c) Armature voltage control
(d) Field diverter control
Answer:

Option (c)

5.
For very sensitive and wide speed control, the preferable control method is
(a) Armature control
(b) Ward-Leonard control
(c) Multiple voltage control
(d) Field control
Answer:

Option (b)

6.
Commutator pitches of duplex and simplex lap windings are respectively
(a) 4 and 2
(b) 2 and 1
(c) 4 and 1
(d) 2 and 2
Answer:

Option (b)

7.
The emf induced in the dc generator armature winding is
(a) AC
(b) DC
(c) AC and DC
(d) None of the above
Answer:

Option (a)

8.
Commutator in DC generator is used for
(a) collecting of current
(b) reduce losses
(c) increase efficiency
(d) convert AC armature current in to DC
Answer:

Option (d)

9.
A DC generator without commutator is a
(a) AC generator
(b) DC motor
(c) DC generator
(d) induction motor
Answer:

Option (a)

10.
In DC machine yoke offers
(a) mechanical protection to the machine
(b) flux path completion
(c) produce working flux
(d) both A and B
Answer:

Option (d)

Showing 1 to 10 out of 167 Questions
1 2 3 4 5 6