DC Motors Most Important Interview Questions - Electronic Engineering
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DC Motors Most Important Interview Questions and Answers. Viva Questions DC motors important question and Answers DC motors.
- Lathe machine
- Centrifugal pump
- Locomotive
- Air blower
Question 1: Which of the following application requires high starting torque?
Answers: Locomotive
- back EMF = 1/2 x supply voltage
- back EMF = 2 x supply voltage
- supply voltage= back EMF
- supply voltage = 1/2 x back e.m.f.
Question 2: The condition for maximum power in case of dc motor is ?
Answers: back EMF = 1/2 x supply voltage
- 8.40%
- 6. 77%
- 2:36 %
- 4.76%
Question 3: The speed of a motor falls from 1100 RPM at no-load to 1050 RPM at rated load. The speed regulation of the motor is?
Answers: 4.76%
- eddy current losses= stray losses
- variable losses = constant losses
- hysteresis losses= eddy current losses
- copper losses = 0
Question 4: The condition for maximum efficiency for a DC generator is?
Answers: variable losses = constant losses
- Rheostatic braking
- Regenerative braking
- Plugging
- Nope of the above
Question 5: Which method of braking is generally used in elevators ?
Answers: Plugging
- will not rotate at all
- rotate in anti-clockwise direction
- gain excessively high speed
- rotate in clockwise direction
Question 6: A DC shunt motor is rotating in clockwise direction as viewed from one end. The polarity of connection of the armature and field winding are reversed simultaneously. The motor will ?
Answers: rotate in clockwise direction
- any unbalanced magnetic pull on the armature core
- all of the above
- twisting strains due to transmission of torque
- bending moment due to the weight of the armature and commutator
Question 7: The armature shaft of a DC motor must be able to withstand?
Answers: all of the above
- Copper losses
- Eddy current losses
- Stray losses
- Friction losses
Question 8: Which losses can be determined by performing the retardation test ?
Answers: Stray losses
- constant torque drive
- variable power drive
- constant power drive
- variable torque drive
Question 9: Speed control by varying the armature circuit resistance, in a DC motor, provides a ?
Answers: constant torque drive
- induction motor
- universal motor
- synchronous motor
- DC series motor
Question 10: A face plate starter is employed for starting ?
Answers: DC series motor
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Total Questions Attempted: 0
Correct: 0 Wrong: 0
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