Electrical Machines Practice Test 3

1. A dc shunt motor is running at 1000 rpm at the rated load torque. If we reverse the supply terminals, then the __________

2. The speed torque of the differential compound dc motor is shown below. What conclusions can be made?

3. The correct positioning of the windings in the below diagrams is?

4. A series generator, having external characteristics which is a straight line through 0 to 50 V at 200 A is connected as a booster, between a station bus-bar and feeders of 0.5 ohm resistors. The voltage at the far end of feeder at current of 50 A is?

5. Which of the following express the starting current nature of the dc motor?

6. For a 7.46 kW, 200 V dc shunt motor with full load efficiency of 85% has armature resistance of 0.25 ohms. Calculate the value of starting resistance in ohms for a current 1.5 times of the full load current.

7. The coil under going commutation lies along _____ while the coil getting short circuited lies along ____ for a practical dc machine.

8. Mark the wrong option. Which of the following cause and effect behaviour in speed control is correct when field resistance is increased.

9. The torque limit of speed for a shunt motor _________

10. A starting resistance is inserted at the starting in an induction motor as well as dc motor.