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WorksheetsMONTHLY TEST OF JANUARY
Total questions: 20
Worksheet time: 20mins
1.A capacitor start single phase induction motor will usually have power factor of
a) Units
b) 0.6 leading
c) 0.8 leading
d) 0.6 lagging
Which of the following single phase motors is cheapest?
a) Capacitor run motor
b) Capacitor start motor
c) Reluctance motor
d) All have almost the same cost
Which of the following single phase motors does not have constant speed characteristic?
a) Reluctance motor
b) Hysteresis motor
c) Universal motor
c) Universal motor
For the same rating which of the following motors has the highest starting torque?
a) Universal motor
b) Split phase motor
c) Synchronous motor
d) All have identical starting torque
b) Split phase motor
c) Synchronous motor
d) All have identical starting torque
The speed of the split phase induction motor can be reversed by reversing the leads of
a) Auxiliary winding
b) Main winding
c) Either (a) or (b)
c) Either (a) or (b)
The rotor of a salient pole alternator has 12 poles. The number of cycles of emf per revolution would be (a)
(a) is used as a exciter for a generator.
In alternators, (a) is generally used with prime movers for high speed applicaton.
As the speed of an alternator increases, the frequency will be (a)
The number of electrical degrees passed through in one revolution of a four pole synchronous alternator is
(a)
Alternator works on the principle of
a) Self and mutual induction
b) Self mutual induction
c) Faraday’s law of electromagnetic induction
d) Mutual induction
Cylindrical rotor alternators have
a) Large length to diameter ratio
b) Small length to diameter ratio
c) Vertical configuration
d) None of these
The synchronous speed of a 8 pole induction motor supplied power from a 50 Hz source, will be
A) 1500 rpm
B) 900 rpm
C) 750 rpm
D) 375 rpm.
A 3-phase slip ring induction motor can be started with which of the following starter ?
A) Stator-rotor starter
B) Star-delta starter
C) Direct-on-line starter
D) Any of the above.
Advantage of slip ring induction motor over squirrel cage induction motor is
a) Suitability of high speeds
b) Higher efficiency
c) Higher power factor
d) That it can be started using factor resistan
Large air gap in an induction motor results in
a) Reduced noise
b) Reduced pulsation losses
c) Better cooling
d) Increased overload capacity
The back emf set up in the stator of synchro-nous motor depends on
a) Speed of the rotor
b) Input to prime mover
c) Rotor excitation
d) Coupling angle
A three phase induction motor connected to 2 phase supply
A) will run at lower rpm
.
B) will run at higher rpm
C) may run with fluctuation in speed and torque
D) may burn
The emf generated in alternator depends on
a) Frequency
b) Flux per pole
c) Coil span factor
d) All of these
The rotor of a salient pole alternator has 12 poles. The number of cycles of emf per revolution would be
(a)
