Electrical Mechine free Model online Test2

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1. By which of the following methods motor rating for variable load drives can be determined ?
Method of average losses	Equivalent current method
Equivalent torque method	All of the above

2. Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?
Equivalent power method	Equivalent current method
Method of average losses	Equivalent torque method

3. Which of the following methods is most accurate ?
Equivalent current method	Equivalent power method
Equivalent torque method	Method of average losses

4. By which of the following methods the temperature rise of windings and other parts may be determined ?
Thermometer method	Resistance method
Embedded temperature detector method	Any of the above

5. The slot leakage can be calculated by making which of the following assumptions ?
The current in the slot conductors is uniformly distributed over their cross-section	The leakage path is straight across the slot and around the iron at the bottom
The permanence of air paths is only considered. The reluctance of iron paths is assumed as zero	All of the above

6. The value of exciting or magnetizing current depends upon which of the following factors ?
Total m.m.f. required	The number of turns in the exciting winding
The way in which the winding is distributed	All of the above

7. Tractive magnets are operated from _____.
a.c. supply	d.c. supply
either a.c. or d.c. supply	none of the above

8. electromagnets generally function as holding magnets.
Tractive	Portative
Either of the above	None of the above

9. Which of the following is the commonly used type of electromagnets ?
Flat-faced armature type	Horse shoe type
Flat-faced plunger type	All of the above

10. _____are used for construction of core of electromagnets.
Soft magnetic materials	Hard magnetic materials
Either (a) or (b)	None of the above

11. The design of electromagnets is based upon which of the following fundamental equations ?
Force equation	Magnetic circuit equation
Heating equation	All of the above

12. When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of _____.
short pitch	full pitch
either of the above	none of the above

13. ______are always double layer type.
Closed windings	Open windings
Either of the above	None of the above

14. The distance between the starts of two consecutive coils measured in terms of coil sides is called _____.
front pitch	winding pitch
commutator pitch	back pitch

15. The winding where dummy coils are used is sometimes called _____.
duplex winding	triplex winding
forced winding	none of the above

16. Dummy coil should not be used in ______.
small machines	large machines
either (a) or (b)	none of the above

17. Power transformers have rating
equal to 50 kVA	equal to 100 kVA
above 200 kVA	none of the above

18. Power transformers should be designed to have maximum efficiency
at one-fourth load	at one-half load
at or near full load	any of the above

19. In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core.
5 percent	10 percent
15 percent	30 percent

20. Yokes with rectangular cross-section are used for _____.
small capacity transformers	medium capacity transformers
large capacity transformers	any of the above