Electrical Machines Practice Test 8

1. A 3-phase, 50 Hz, 6-pole induction motor has a shaft output of 10kW at 930 rpm. Friction and windage losses is 1% of the output. Total stator losses is 600W. What is the stator input?

2. The electrical anlogous of the mechanical load in the induction machine is given by?

3. A 10kW,400V, 4-pole delta connected induction motor gave the following test results:

No-load test: 400V, 8A, 250 W
Blocked rotor test: 90V, 35A, 1350 W

The dc resistance per phase is 0.6 ohms. The effective stator resistance is?

4. Below is the torque slip characteristic of the induction machine. What can be inferred from it?

5. Starters are required in the induction motor because __________

6. Which tests are to be conducted to draw circle diagram for a given induction motor?

A. Running light test
B. Slip test
C. Voltmeter-Ammeter test

7. The stator current of the induction motor is given by which of the below?

8. Stator equivalent circuit for polyphase induction motor is?

9. A 3-phase induction motor had the maximum rated torque of 40 N-m while the load torque applied to it is 55 N-m.

10. A 3-phase, 4-pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by auto transformer method of starting with a tapping ratio of 'x', then the starting torque will be?