Answer:
) The torque developed by a DC motor is directly proportional to ________
Flux per pole ∗ armature current
Armature resistance ∗ armature current
Armature resistance ∗ applied voltage
None of the above
ANSWER
Answer: ( 1 )
EXPLANATION
22) The shaft torque (Tsh) in a DC motor is less than the total armature torque (Ta) because of ___________ in the motor.
Cu losses
Field losses
Iron and friction losses
None of the above
ANSWER
Answer: ( 3 )
EXPLANATION
23) Armature reaction in a DC motor is increased _________
When the armature current increases
When the armature current decreases
When the field current increases
By interpoles
ANSWER
Answer: ( 1 )
EXPLANATION
24) In a DC motor, the brushes are shifted from the mechanical neutral plane in a direction opposite to the rotation to _______
Decrease speed
Increase speed
Reduce sparking
Produce flat characteristics
ANSWER
Answer: ( 3 )
EXPLANATION
25) In very large DC motors with severe heavy duty, armature reaction effects are corrected by ________
Using interpoles only
Using compensatory winding’s in addition to interpoles
Shifting the brush position
None of the above
ANSWER
Answer: ( 2 )
EXPLANATION
26) The speed of a ________ motor is practically constant.
Cumulatively compounded
Series
Deferentially compounded
Shunt
ANSWER
Answer: ( 4 )
EXPLANATION
27) Which of the following is not necessarily the advantage of DC motors over AC motors?
High starting torque
Wide speed range
Better speed control
Low cost
ANSWER
Answer: ( 4 )
