Related Questions

A rheostat differs from potentiometer in the respect that it
A Has lower wattage rating
B Has higher wattage rating
C Has large number of turns
D Offers large number of tapping
When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
A inductor motor torque
B induction generator torque
C synchronous motor torque
D d.c. motor toque
In case of __________ speed control by injecting e.m.f. in the rotor circuit is possible,
A D.C. shunt motor
B Schrage motor
C Synchronous motor
D Slip ring induction motor
In order to reduce the rotor speed of an impulse turbine, the method employed is
A Velocity compounding
B Pressure compounding
C Pressure-velocity compounding
D All of these
The respective ratio between the speed of a speed of the car, bus and train is 5 : 9 : 6. The average speed of the car, bus and train is 72 km/hr together. What is the average speed (km/h)of the car and the train together?
A 82
B 72
C 67
D 84
When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor
A remains same as the original value
B decreases to half the original value
C tends to becomes zero
D increases to two times the original value
In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
A Universal motor
B Synchronous motor
C Induction motor
D Reluctance motor
What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero?
A The slip of the motor will be 5%
B The rotor will not run
C The rotor will run at very high speed
D The torque produced will be very large
For which motor the speed can be controlled from rotor side?
A Squirrel-cage induction motor
B Slip-ring induction motor
C Both (A) and (B)
D None of the above
Besides a constant speed a synchronous rotor possesses which of the following advantages?
A Lower cost
B Better efficiency
C High power factor
D All of the above

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