1. Which test is used to determine the efficiency of a traction motor?
- Field’s test
- Hopkinson’s test
- Retardation test
- Swinburne’s test
2. A 460 V series motor runs at 500 rpm taking a current of 40 A. Calculate the percentage change in torque if the load is changed so that the motor takes 30 A.
- 43.75 %
3. Which of the following are the advantages of the Field Test of DC Motor?
- Easy determination of stray losses
- Uniform Load Distribution
- Same Iron losses
- All of the above
4. Which of the following are the disadvantages of DC motor Field test?
- Bulky Setup
- High Energy Consumption
- Both 1 and 2
- None of the above
5. In a DC series motor, the ratio of back emf (E to supply voltage (V) indicates:
- Running torque
- Speed regulation
- Starting torque
6. What is the relationship between the speed (N) and armature current (I in the case of a dc-series motor?
- N ∝ 1/Ia
- N ∝ √(I
- N ∝ I2a
- N = Ia
7. For a DC series motor, the torque is ________ to the speed.
- Directly Proportional
- Inversely Proportional
- Equal to
8. A ________ motor runs at the highest speed when the load is removed.
- Cumulatively compound
- Differentially compound
9. A d.c. series motor has linear magnetization characteristics and negligible armature resistance. The motor speed is
10. What happens if an ordinary DC series motor is connected to an AC supply?
- The motor is in standstill condition.
- It will rotate and exert unidirectional torque.
- It will oscillate and exert unidirectional torque
- It will rotate and exert bidirectional torque