Single phase induction motors Archives

31. In a capacitor start single-phase motor, when capacitor is replaced by a resistance

torque will increase

the motor will consume less power

motor will run in reverse direction

motor will continue to run in same direction

Detailed SolutionIn a capacitor start single-phase motor, when capacitor is replaced by a resistance

32. In a shaded pole single-phase motor, the revolving field is produced by the use of

inductor

capacitor

resistor

shading coils

Detailed SolutionIn a shaded pole single-phase motor, the revolving field is produced by the use of

33. The electric motor used in portable drills is

capacitor run motor

hysteresis motor

universal motor

repulsion motor

Detailed SolutionThe electric motor used in portable drills is

34. Which of the following motors is used in tape-recorders ?

Hysteresis motor

Reluctance motor

Capacitor-run motor

Universal motor

Detailed SolutionWhich of the following motors is used in tape-recorders ?

35. For which of the applications a reluctance motor is preferred ?

Electric shavers

Refrigerators

Signalling and timing devices

Lifts and hoists

Detailed SolutionFor which of the applications a reluctance motor is preferred ?

36. In a universal motor, the most common cause of brush sparking is

open armature winding

shorted armature winding

shorted field winding?

high commutator mica E. all of the above

Detailed SolutionIn a universal motor, the most common cause of brush sparking is

37. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then

motor will not come up to speed

motor will not carry the load

current drawn by the motor will be excessively high

electrolytic capacitor will, in all probability, suffer break down

Detailed SolutionIf the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then

38. To reverse the direction of rotation of acapacitor start motor while it is running we should

disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding

disconnect motor from supply and immediately reconnect it to supply with reversed con-nections of the main winding

reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply

reverse the direction of connections of the auxiliary winding and immediately connect it to supply

Detailed SolutionTo reverse the direction of rotation of acapacitor start motor while it is running we should

39. The power factor of a single-phase induction motor is usually

lagging

always leading

unity

unity to 0.8 leading

Detailed SolutionThe power factor of a single-phase induction motor is usually

40. Which of the following single-phase induction motors is generally used in time phonographs?

Resistance start

Capacitor start capacitor run

Shaded pole

Universal

Detailed SolutionWhich of the following single-phase induction motors is generally used in time phonographs?