Dynamic Braking MCQs : This section focuses on the "Dynamic Braking" in Electric Drives. These Multiple Choice Questions (MCQ) should be practiced to improve the Electric Drives skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
____________ is the use of an electric traction motor as a generator when slowing a vehicle such as an electric or diesel-electric locomotive.
A. Regenerative Braking
B. Dynamic braking
C. Countercurrent Braking
D. All of the above
View Answer
Ans : B
Explanation: Dynamic braking is the use of an electric traction motor as a generator when slowing a vehicle such as an electric or diesel-electric locomotive.
Question 2
Dynamic braking _________ wear on friction-based braking components.
A. increases
B. no effect
C. reduces
D. can not say
View Answer
Ans : C
Explanation: Dynamic braking reduces wear on friction-based braking components, and regeneration lowers net energy consumption.
Question 3
Dynamic braking used on ?
A. hybrid electric automobiles
B. trolleybuses
C. electric trams
D. All of the above
View Answer
Ans : D
Explanation: Dynamic braking may also be used on railcars with multiple units, light rail vehicles, electric trams, trolleybuses and electric and hybrid electric automobiles.
Question 4
Which braking method is the best method for obtaining high braking torque?
A. Regenerative braking
B. Plugging
C. Dynamic braking
D. Rheostatic braking
View Answer
Ans : B
Explanation: Plugging is the best braking method among all braking techniques. In plugging the value of the armature current reverses and the mechanical energy is extracted. A very high braking torque is produced in case of plugging.
Question 5
How many main methods of managing the electricity generated during dynamic braking?
A. 2
B. 3
C. 4
D. 5
View Answer
Ans : A
Explanation: The two main methods of managing the electricity generated during dynamic braking are rheostatic braking and regenerative braking.
Question 6
For permanent magnet motors, dynamic braking is easily achieved by shorting the motor terminals.
A. TRUE
B. FALSE
C. Can be true or false
D. can not say
View Answer
Ans : A
Explanation: True, For permanent magnet motors, dynamic braking is easily achieved by shorting the motor terminals, thus bringing the motor to a fast abrupt stop.
Question 7
Full form of SCIM.
A. Squirrel cage inverter motor
B. Solid cage induction motor
C. Square cage induction motor
D. Squirrel cage induction motor
View Answer
Ans : D
Explanation: SCIM stands for squirrel cage induction motor. SCIM rotor is made up of aluminum, copper bars. There are no armature conductors involved in it.
Question 8
The polarity of back e.m.f changes in which of the method?
A. Regenerative braking
B. Dynamic braking
C. Plugging
D. Rheostatic braking
View Answer
Ans : C
Explanation: In case of Plugging braking technique polarity of the back e.m.f voltage changes due to which current direction changes and mechanical, electrical energy are wasted in the form of heat in resistors
Question 9
Reactive power is positive in the case of the inductor.
A. TRUE
B. FALSE
C. Can be true or false
D. can not say
View Answer
Ans : A
Explanation: True, The reactive power is defined as the product of the voltage, current, and sine of the difference between the phase angle of voltage and current. In the case of an inductor, the voltage leads the current. The value of sine is positive and reactive power is positive
Question 10
Reactive power is positive in the case of the capacitor
A. TRUE
B. FALSE
C. Can be true or false
D. can not say
View Answer
Ans : B
Explanation: False, The reactive power is defined as the product of the voltage, current, and sine of the difference between the phase angle of voltage and current. In the case of a capacitor, the voltage lags the current. The value of sine is negative and reactive power is negative.