WorksheetsEE-II - SPEED CONTROL OF DC MOTOR
Total questions: 10
Worksheet time: 5mins
1. The PWM control of DC motor varies _________
a) linearly with speed
b) inversely with speed
c) parabolically with speed
d) exponentially with speed
Mark the wrong option. Which of the following cause and effect behaviour in speed control is correct when field resistance is increased.
a) Decrease in flux
b) Increase in armature current
c) Increase in EMF
d) Decrease in speed
At a very low speed, increase in field resistance will _________
a) decrease the speed of motor
b) increase the speed of motor
c) not have signicant effect on speed
d) no effect
Small DC motors have best speed control by _________
a) armature voltage control
b) field resistance control
c) any of the methods
d) none of the mentioned
To implement armature voltage control, it must be ensured that _________
a) it is used on separately excited machine
b) it is used on shunt machine
c) it is used on series machine
d) any of the mentioned machine
Armature voltage control works for speeds _____ base speed and field resistance control works well for speed _____ base speed.
a) below, above
b) above, below
c) above, above
d) below, below
Speed of d.c. shunt motors are controlled by
a. Flux control method
b. Rheostatic control method
c. Voltage control method
d. All of these
With the increase in temperature, the speed of series and shunt motor will
a. Increase, decrease
b. Decrease, increase
c. Increase, increase
d. Decrease, decrease
In the flux control method for controlling the speed of d.c. shunt motor, the speed control is not possible
a. Below normal rated speed
b. Above normal rated speed
c. Both (a) and (b)
d. None of these
If a resistance is added in series with the field winding of d.c. shunt motor, then its
a. Both speed and torque decreases
b. Both speed and torque increases
c. Speed decreases, torque increases
d. Speed increases, torque decreases
