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
The characteristics of drive for crane hoisting and lowering are which of the following ?
(A) Precise control
(B) Smooth movement
(C) Fast speed control
(D) All of the above
A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is____________________?
(A) slop speed operation
(B) high starting torque
(C) low windage losses
(D) all of the above
By the use of which of the following m D.C. can be obtained from AC. ?
(A) Silicon diodes
(B) Mercury arc rectifier
(C) Motor generator set
(D) Any of the above
Heavy duty cranes are used in________________?
(A) ore handling plants
(B) steel plants
(C) heavy engineering workshops
(D) all of the above
In ______________ the speed can be varied by changing the position of brushes?
(A) slip ring motor
(B) schrage motor
(C) induction motor
(D) repulsion motor
For a motor-generator set which of the following motors will be preferred ?
(A) Synchronous motor
(B) Slip ring induction motor
(C) Pole changing induction motor
(D) Squirrel cage induction motor
In ________________ method of staging three phase induction motors the starting voltage is not reduced?
(A) auto-transformer
(B) star-delta
(C) slip ring
(D) any of the above
Battery operated scooter for braking uses________________?
(A) plugging
(B) mechanical braking
(C) regenerative braking
(D) rheostatic braking
Which of the following types of motor enclosure is safest ?
(A) Totally enclosed
(B) Totally enclosed fan cooled
(C) Open type
(D) Semi closed