Electrical Drives Multiple Choice Questions and Answers

21. What are the constituents in speed time curve of train?

1. Constant speed
2. Coasting
3. Initial acceleration
4. All of the above

22. What type electric drive is used in cranes?

1. Individual
2. Multimotor
3. Group
4. Both A and C

23. Which braking is not possible in series motor?

1. Counter current braking
2. Regenerative braking
3. Dynamic braking
4. Rheostat braking

24. Which of the following are electrical braking methods ?

1. regenerative
2. plugging
3. dynamic
4. All of the above

25. Which speed control method preferred for constant torque drive?

1. Mechanical loading system
2. Field control
3. Armature voltage control
4. None of these

26. While operating on variable frequency supplies, the AC motor requires variable voltage in order to

1. improve the capabilities of the inverter
2. protect the insulation
3. avoid effect of saturation
4. protect thyristor from dV / dt