1
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Describe the different types of single phase
induction motor.
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Types of
single phase induction motor
- Split phase induction motor
- Capacitor start induction run motor
- Shaded pole motor
- Repulsion motor : ( 1 ) Compensated repulsion motor (
2 ) Repulsion start induction run motor and ( 3 ) Repulsion induction motor
- AC series motor
- Unexcited synchronous motor : ( 1 ) Hysteresis motor
and ( 2 ) Reluctance motor
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2
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Which type of construction the single phase
induction motor consists of?
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The single phase induction motor consists of
Stator
- It consists of starting and running winding. Both
windings are placed 900 with respect to each other.
Rotor
- It is squirrel cage type.
Centrifugal
switch
- It is provided in motor to cut out starting winding.
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3
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Give reason : The single phase induction motor is
not self starting.
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Single phase induction motor not self starting
- The single phase winding produces pulsating or
alternating flux which acts on the stationary squirrel cage rotor.
- This flux
does not produce any rotation therefore the single phase induction motor is
not self starting. ( The forward and backward rotating torque in the single
phase induction motor is equal and opposite at standstill therefore the net
torque is zero. )
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4
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What is backward rotating slip of the induction
motor if the forward rotating slip is s?
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2 – s
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5
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On which factor the starting torque of the split
phase induction motor depends?
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The starting torque in the split phase induction
motor is directly proportional to sin α. ( Where α is angle between starting
winding current and running winding current )
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6
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Describe the function of the centrifugal switch in
the single phase induction motor.
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Function of the centrifugal switch
- The function of the centrifugal switch is to disconnect
starting winding from the main supply when the motor speed reaches 70 to 80%
of the full load speed.
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7
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Where the relay coil is connected in the split phase
induction motor?
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The relay coil is connected is in series with main
winding whereas the pair of its contacts are connected in series with the
starting winding.
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8
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Which winding has high resistance in the split phase
induction motor? Main winding or starting winding
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The main winding of the split phase induction motor
has high reactance but low reactance whereas the starting winding has high
resistance but low reactance.
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9
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State the applications of the split phase motor.
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Applications
- Centrifugal pumps
- Fans
- Blowers
- Washing machines
- Duplicating machines
- Oil burners
- Refrigerators
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10
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Give reason : The split phase induction motor is
constant speed motor.
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Speed Regulation
- The speed of the split phase induction motor varies about 2 to 5%
between no load to full load.
- Therefore it is called as constant speed motor.
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11
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How the phase split is done in the capacitor start
induction motor?
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The phase split in the capacitor start induction
motor is done by connecting a capacitor is in series with the starting
winding.
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12
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Which type of capacitor is used in the capacitor
start induction motor?
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Short duty electrolyte capacitor
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13
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Which type of induction motor has high starting
torque, split phase or capacitor start induction motor? Why?
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High starting torque
- The capacitor start induction motor has high
starting torque as compared to split phase motor because the angle between
starting winding current and running winding current is 800 in the
capacitor motor as compared to 300 in the split phase motor.
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14
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Why the capacitor is provided in series with
starting winding in the capacitor start induction motor?
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Function
of capacitor
- To provide necessary phase difference between
starting and running winding.
- It provides necessary high starting torque.
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15
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Describe the function of capacitor in the capacitor
start and capacitor run motor.
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Function
of capacitor
- It increases the power factor
- High efficiency
- Overload capacity increases
- Noiseless operation
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16
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Which motor works as unbalanced two phase motor?
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Single value capacitor run motor
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17
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Whether any centrifugal switch is necessary in the
single value capacitor run motor?
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No
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18
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Which type of capacitor is used in the single value
capacitor run motor?
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Continuous duty rating motor, Pyranol insulated foil
paper capacitor
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19
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State the applications of the single value capacitor
motor.
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Application
- Induction regulator
- Furnace control
- Rheostat
- Arc welding control
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20
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What do you mean by single value capacitor motor and
two value capacitor motor?
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Single
value capacitor motor
- The single value capacitor motor is one in which one
capacitor is used during starting as well as running condition.
Two
value capacitor motor
- The two value capacitor is one in which high value
of capacitor is used during starting condition and low value of capacitor is
used during running condition.
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