# Electric Drives Questions and Answers – Electrical Drive Systems

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This set of Electric Drives Multiple Choice Questions & Answers (MCQs) focuses on “Electrical Drive Systems”.

1. Calculate the minimum anode current required to turn off SCR if the latching current value is 2 A.
a) 2 A
b) 3 A
c) 4 A
d) 5 A

Explanation: The minimum anode current required to turn off the SCR is the latching current. The value of the latching current is 2 A.

2. Calculate the value of the coefficient of static friction using the data: F=4 N, Normal force=16 N.
a) .24
b) .25
c) .15
d) .14

Explanation: Coefficient of friction is the ratio of the friction force and normal force. It is dependent on the smoothness of the surface area. μ = 4÷16 = .25.

3. Full form of TVS is __________
a) Transient voltage suppression
b) Transient voltage surge
c) Total voltage surge
d) True voltage surge

Explanation: The full form of TVS is Transient voltage suppression. It is one of the types of light surge suppressors. It is used to suppress transient voltages.
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4. The frictional force always acts in the perpendicular direction of motion of the body.
a) True
b) False

Explanation: The friction of force always acts in the opposite direction of the motion of the body. It is a non-conservative force. It helps in the motion of the body.

5. Calculate the coefficient of friction if the angle of inclination is 0°.
a) 2
b) 1
c) 4
d) 0

Explanation: The coefficient of friction is the tangent of the angle of the inclined plane. The value of μ is the tan(0°) = 0. The coefficient of friction depends on the nature of the surface.

6. When was the first train built?
a) 1804
b) 1810
c) 1814
d) 1820

Explanation: Richard Trevithick built the first train in 1804. It was a steam locomotive train that used to carry 10 tonnes of iron from one place to another.

7. Who invented the first circuit breaker?
a) Albert Einstein
b) Thomas Edison
c) Nicola Tesla
d) Trent Boult

Explanation: Thomas Edison was the inventor of the circuit breaker. It was designed in 1879. It was an early form of the circuit breaker.

8. The power conductor in electric trains is called a contact wire.
a) True
b) False

Explanation: The supply conductor in electric trains is also known as Contact wire. Driving motor and power modulators are housed in the locomotive.

9. Full form of LSS is ____________
a) Line Surge Suppressors
b) Local Surge System
c) Local Surge Suppressors
d) Line Surge System

Explanation: Full form of LSS is Line surge suppressors. They are used to protect the semiconductor converter against voltage spikes produced in line.

10. Calculate the value measured by PMMC when a sinusoidal voltage signal V(t)=20sin(ωt) is applied to it.
a) 1 V
b) 2 V
c) 6 V
d) 0 V

Explanation: Permanent magnet moving coil instrument measures the average value of the input signal. The average value of the sinusoidal signal is 0 V.

11. Full form of MCC is ____________
a) Motor control center
b) Motor counter center
c) Machine control center
d) Motor coil counter

Explanation: The full form of MCC is Motor control center. It controls the power to system drives. There can many MCCs exist in an area.

12. Full form of PCC is ____________
a) Producer control center
b) Poor counter center
c) Power control center
d) Power coil counter

Explanation: The full form of PCC is Power control center. They receive power from the main power distribution center.

13. Current Chopping is most severe in which one of the following?
a) Air Blast Circuit Breaker
b) Oil Circuit Breaker
c) Air Break Circuit Breaker
d) Vacuum Circuit Breaker

Explanation: Current chopping is most severe in the case of Air blast circuit breaker. Resistance switching is used to avoid the problem of current chopping.

14. Oil circuit breaker is mainly used in _____________
a) Synchronous machine
b) Induction machine
c) DC machine
d) Transformer

Explanation: Oil circuit breaker is mainly used in transformers. The oil acts a coolant for the transformer. When a fault occurs in the transformer oil decomposes in the gases.

15. Full form of PLC is ____________
a) Programmable Logic Controller
b) Programmable Language Controller
c) Peterson Language Counter
d) Programmable Logic Counter

Explanation: The full form of PLC is Programmable logic controller. It is a computer control system that monitors input states and makes decisions based upon a program to control output states.

Sanfoundry Global Education & Learning Series – Electric Drives.

To practice all areas of Electric Drives, here is complete set of 1000+ Multiple Choice Questions and Answers.