1. The number of parallel path in a simplex lap winding is equal to
(a) number of poles
(b) number of pole pairs
(c) two
(d) two times number of pole
Answer
2. The number of parallel path in a simplex wave windings are equal to
(a) two
(b) number of poles
(c) number of poles pairs
(d) no of coils
Answer
3. The number of parallel path in a 8-pole duplex wave winding is equal to
(a) 2
(b) 4
(c) 8
(d) 16
Answer
4. The number of parallel path in a 8-pole duplex lap winding is equal to
(a) 4
(b) 8
(c) 16
(d) 32
Answer
5. In DC machine, the fractional pitch winding is used to
(a) produce vibration
(b) reduce sparking
(c) avoid hunting
(d) avoid magnetic locking
Answer
6. In a DC machine, the sparking at the brushes is due to
(a) low contact resistance
(b) reactance voltage
(c) armature reaction
(d) over excitation
Answer
7. When the field excitation of a DC generator increases, its generated emf
(a) decreases
(b) increases
(c) remain same
(d) first increases then constant
Answer
8. The field coil of a DC machine are usually made of
(a) copper
(b) aluminium
(c) carbon
(d) mica
Answer
9. Then insulating material used between commutator segment is generally
(a) paper
(b) mica
(c) plastic
(d) fibre
Answer
10. The function of dummy coils in DC machines is to
(a) reduce armature reaction
(b) provide alternate flux
(c) reduce losses
(d) provide mechanical balancing
Answer
11. Permeability is reciprocal of
(a) susceptibility
(b) reluctivity
(c) permittivity
(d) conductivity
Answer
12. The purpose of using dummy coil in a DC machine is to
(a) reduce losses
(b) reduce armature reaction
(c) provide mechanical balance to armature
(d) improve power factor
Answer
13. The rotor part of a DC machine carries
(a) armature winding
(b) field winding
(c) either field or armature winding
(d) none of the above
Answer
14. If a field winding designed for series connection is connected in parallel, the machine will
(a) draw very high current
(b) stand still
(c) run normally
(d) run at slow speed
Answer
15. In the commutative compound machine, the mmf of the series field winding will ________ to the mmf of the shunt field winding.
(a) add
(b) minus
(c) same
(d) half
Answer
16. Which is the basic dominant factor in the production of the magnetic flux in a compound machine?
(a) Shunt field mmf
(b) Series field mmf
(c) Both shunt and series field mmf
(d) None of the above
Answer
17. The principle of dynamically induced emf is used in
(a) generator
(b) battery
(c) transformer
(d) all of the above
Answer
18. A dummy coil may required in a DC machine, if the machine is
(a) lap wound
(b) wave wound
(c) either lap or wave wound
(d) none of the above
Answer
19. In a DC Machine, the frog leg wound armature are designed for the use with
(a) high current high voltage
(b) high current low voltage
(c) moderate current and moderate voltage
(d) low current and low voltage
Answer
20. Which of the following is main factor to determine the size and rating of and electric machine?
(a) Current
(b) Temperature
(c) Speed
(d) Voltage
Answer
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