SOME IMPORTANT MCQ FOR ELECTRICAL STUDENTS
(20 mcq, synchronous machine)
1. Alternator operates on the
principle of
(a) electromagnetic induction
(b) self induction.
(c) mutual induction
(d) self or mutual induction
2.The armature bof an alternator
(a) is a stationary member
(b) is revolving member
(c) is the frame
(d) consisting of the winding into which current is induced
3. In morden alternator, the rotating part is
(a) field system
(b) armature
(c) armature as well as field system
(d) none of the above
4.The current from the stator of an alternator is taken out the external load circuit through
(a) slip rings
(b) commentator segments
(c) solid connections
(d) carbon brushes
5.An alternator is .
(a) a polyphase synchronous machine
operated with dc exciter
(b) a polyphase synchronous machine operated with ac exciter
(c) a three phase induction machine with prime mover.
(d) any ac generator
6. Which type of alternator is used in hydroelectric power stations ?
(a) Non salient pole alternator
(b)Turbo generator
(c) salient pole alternator
(d) stream turbine alternator
7. In a synchronous machine the, stator frame is made of
(a) stainless steel
(b) CRGOS
(c) cast iron
(d) cast steel
8. The stator core of a synchronous machine is built up of ................. laminations
(a) stainless steel
(b) silicone steel
(c) cast iron
(d) cast steel
9. The slip rings employed in a 3 phase synchronous machine are insulated for
(a) output rated voltage
(b) low voltage
(c) very low voltage
(d) very high voltage
10. Hydro-generators are generally employed to run at
(a) 500
(b) 1,000
(c) 1,500
(d) 3,000
11. The salient pole rotors have
(a) two or four projecting poles carrying the field coils
(b) a large number of projecting poles carrying the field coils
(c) thick steel laminations riveted together and fixed to the rotor by a dova-tail joint
(d) pole faces usually provided with slots for damper winding
(e) all of the above except (a)
12. Large diameter of salient pole field structure, the pole shoes cover about... of pole pitch
(a) it occupies much less space
(b) it saves lot of copper in stator winding
(c) it reduces weight of the motor
(d) number of conductors held in large circumference of rotor is very large and so they need not be long
13. The stator of modern alternator are wound for...... phase group
(a) 180⁰
(b) 120⁰
(c) 60⁰
(d) 240⁰
14. For a two layer winding the number of stator slots is equal to the number of
(a) poles
(b) conductor
(c) coils side
(d) coils
15. The armature reaction effect in a synchronous machine depends on
(a) load current
(b) power factor of the load
(c) speed of machine
(d) both a and b
16. A leading power factor load on an alternator implies that it's voltage regulation shall be
(a ) positive
(b) negative
(c) zero
(d) any of these
17. A pony motor is basically a
(a) small induction motor
(d) dc series motor
(c) dc shunt motor
(d) double winding ac/dc motor
18. When a synchronous motor is running at synchronous speed ,damper winding produces
(a) damping torque
(b) eddy current torque
(c) torque aiding the developed torque
(d) no torque
19. While starting synchronous motor its field winding should be
(a) kept open
(b) short circuited
(c) connected to a dc source
(d) none of the above
20. which of the following motor is not a synchronous motor ?
(b) Hysteresis
(b) Repulsion
(c) inductors
(d) Reluctance
No comments:
Post a Comment