Single phase induction motors Archives

91. Which of the following applications always have some load whenever switched on ?

Vacuum cleaners

Fan motors

Pistol drills

All of the above

Detailed SolutionWhich of the following applications always have some load whenever switched on ?

92. In a split phase motor, the running winding should have

high resistance and low inductance

low resistance and high inductance

high resistance as well as high inductance

low resistance as well as low inductiance

Detailed SolutionIn a split phase motor, the running winding should have

93. In which single-phase motor, the rotor has no teeth or winding ?

Split phase motor

Reluctance motor

Hysteresis motor

Universal motor

Detailed SolutionIn which single-phase motor, the rotor has no teeth or winding ?

94. A centrifugal switch is used to disconnect starting winding when motor has

run for about 1 minute

run for about 5 minutes

picked up about 50 to 70 per cent of rated speed

picked up about 10 to 25 per cent of rated speed

Detailed SolutionA centrifugal switch is used to disconnect starting winding when motor has

95. In repulsion motor direction of rotation of motor

Is opposite to that of brush shift

Is the same as that of brush shift

Is independent of brush shift

nan

Detailed SolutionIn repulsion motor direction of rotation of motor

96. Which of the following statements regarding repulsion-start induction motor is incorrect ?

It requires more maintenance of commutator and other mechanical devices

It makes quite a bit of noise on starting

In fractional horse power motors, it has replaced the capacitor motors

It is not easily reversed

Detailed SolutionWhich of the following statements regarding repulsion-start induction motor is incorrect ?

97. In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will

Become unstable

Draw excessive armature current and may burn out

Fall out of synchronism and come to stand still

Run as induction motor

Detailed SolutionIn case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will

98. In a

through resistance

through reactances

series motor armature coils are usually connected to commutator A. through resistance B. through reactances C. through capacitors

solidly

Detailed SolutionIn a

99. If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in

Damage to the starting winding

Damage to the centrifugal switch

Overloading of running winding

None of the above

Detailed SolutionIf the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in

Page 1 Page 2 Page 3 Page 4 Page 5

Test 1 Test 2

Exit mobile version