1q Induciton Motor | Electric Motor | Capacitor

May 13, 2018 | Author: Anonymous | Category: Documents
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A centrifugal switch is used to disconnecting starting winding when motor has .... The direction of rotation of universa...

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OBJECTIVE ELECTRICAL ENGINEERING

1Q INDUCTION MOTOR

1. In capacitor stator 1Q motor (a) Current in starting winding loads the voltage (b) Current in starting winding lag the voltage (c) Current in starting winding is in phase with the voltage in running winding (d) None of the above

7. On a split phase motor the starting winding should have (a) High resistance and low inductance (b) Low resistance and high inductance (c) High resistance as well as inductance (d) Low resistance as well as inductance Ans a 8. In a split phase motor running winding should have (a) Low resistance as well as inductance (b) High resistance as well as inductance (c) Low resistance and high inductance (d) High resistance and low inductance

Ans a 2. In a capacitor start motor the phase displacement between starting and running winding can be nearly 0 (a) 10 0 (b) 30 0 (c) 60 (d) 900

Ans c

9. The maximum split that can be advanced with the split phase motor is nearly Ans d 0 (a) 10 electrical 3. In a capacitor start and run motor the (b) 300 electrical 0 function of the starting capacitor in series (c) 60 electrical with the axcillary winding is (d) 900 electrical (a) To improve torque Ans b (b) Reduce fluxtion in torque (fluctuation) (c) Increase over load capacity 10. The torque developed by a 1Q motor at (d) To improve P.F starting is (a) More than the rated torque Ans d (b) Rated torque 4. The motor provided for 1Q is usually (c) Less than rated torque (a) Split phase motor (d) Zero torque (b) Capacitor start motor Ans d (c) Capacitor start and run motor (d) Universal motor 11. Which of the following motor will give relatively high starting torque Ans c (a) Shaded pole motor 5. If the capacitor of 1Q motor is short (b) Capacitor run motor circuited (c) Split phase motor (a) The motor will burn (d) Capacitor start motor (b) The motor will not start Ans d (c) The motor will run in reverse direction (d) The motor will run in same direction 12. A capacitor start 1Q induction motor is reduced speed switched on to supply with its capacitor replaced by an inductor of equivalent Ans b value then motor will 6. For the same horse power torque, rpm, (a) Not start and operating voltage, the slip will be (b) Start and run (a) More in single phase motor (c) Start and than still (b) More in 3Q motor (d) Burn (c) The same in three phase as well as Ans b single phase (d) None of the above 13. Which type of capacitor is preferred for capacitor start and run motor Ans a (a) Air capacitor Page 1

OBJECTIVE ELECTRICAL ENGINEERING

(b) (c) (d)

1Q INDUCTION MOTOR

Paper capacitor (oil field) Ceramic capacitor Electrolytic capacitor

(a) (b) (c) (d)

Ans b 14. Which of the following motor will have relatively high P.F (a) Split phase motor (b) Shaded pole motor (c) Capacitor start motor (d) Capacitor run motor Ans d 15. Hermetically sealed motors are iommonly used in (a) Ceiling fan (b) Blower (c) Refrigerator (d) Mixi Ans c

Shaded pole motor Capacitor start motor Capacitor start and run motor Universal motor Ans d

20. In celing fan motor the rotor is usually supported in (a) Ball-bearings (b) Bush-bearing (c) Cast iron bearing (d) No bearing is used in motor Ans a 21. The balls for ball bearing are made by (a) Casting (b) Roling (c) Turning (d) Cold heating Ans d

16. A shaded pole single phasemotor i s generally not used due to all of the following resons except (a) Poor starting torque (b) Low P.F (c) Low speed operation (d) Irreversibility of direction of rotation Ans c 17. In a shaded pole 1Q motor the revolving field is producing by the use of (a) Inductor (b) Capacitor (c) Resistor (d) Shading coil(ring) Ans d 18. A centrifugal switch is used to disconnecting starting winding when motor has (a) Run for about 5 min (b) Run for about 1 min (c) Pick up about 50%-70% speed of rated speed (d) Pick up about 10%-25% speed of rated speed Ans c 19. If a particular application need high speed and high starting torq ue then which of the following motor will be preferred Page 2

22. Which motor as highest power to weight ratio (a) Universal motor (b) Capacitor start motor (c) Capacitor run motor (d) None of the above Ans a 23. A single phase motor is usually started by (a) Star delta starter (b) Auto T/F starter (c) D.O.L starter (d) None of the above Ans c 24. Single phase capacitor start motor single voltage none reversible with magnetic switching are commonly used in (a) Refrigerator (b) Ceiling fan (c) Toys (d) Cranes Ans c 25. In shaded pole motor nece ssary phase splitting is produced by (a) Induction (b) Inductance (c) Resistance (d) Capacitance

OBJECTIVE ELECTRICAL ENGINEERING

1Q INDUCTION MOTOR

Ans a

Ans d

26. In a universal motor the width of the brush is nearly (a) Half of the width of commutator segment (b) Equal of the width of commutator segment (c) Equal of the width of two commutator segment (d) Equal to the width of four commutator segment Ans c 27. Motorisc hard tools generally used (a) Capacitor start motor (b) Reluctance motor (c) Shaded bole motor (d) Universal motor

32. The P.F of single phase motor is usually (a) Unity (b) Unity to .8 lagging (c) Always loading (d) Lagging .6 to .8 Ans d 33. Which of the following motor does not have a centrifugal switch (a) Capacitor start motor (b) Capacitor run motor (c) Split phase motor (d) None of the above Ans b

Ans d 28. If motor speed 5000 rpm is desire, which of the following motor will be obgous choice (a) Hysteresis motor (b) Reluctance motor (c) Universal motor (d) Capacitor start cp.run motor Ans c 29. Shaded pole motors are built commercially in size (a) 1/250 HP to 1/6 HP (b) ¼ HP to 1 HP (c) 1 HP to 2 HP (d) 2 HP to 5 HP

34. A shaded pole motor can be used for (a) Hair dryer (b) Toys (c) Circulators (d) All of the above Ans d 35. What will happen when the capacitor of a capacitor start motor is replaced by an inductance of same reactance (a) The motor will burn (b) The inductance will burn (c) Motor run in reverse direction (d) The motor will produce high torque Ans c

Ans a 30. The range of efficiency for shaded pole motor is (a) 95-99% (b) 80-90% (c) 50-75% (d) 5-35% Ans d

36. A hysteresis works only principle of (a) Hysteresis loss (b) Magnetization of motor (c) Eddy current losses (d) Electro magnetic induction Ans a 37. Which of the following motor will give highest torque (a) Schrage motor (b) D.c shunt motor (c) Universal motor (d) Repulsion start and induction run motor

31. In a capacitor start 1Q motor, when capacitor replaced by a resistor Ans a (a) The motor will consume less power (b) Torque will increase 38. Which of the following single phase motor (c) The motor will run in reverse direction has a commutator (d) The motor will run in same direction (a) Capacitor start motor (b) Capacitor run motor Page 3

OBJECTIVE ELECTRICAL ENGINEERING

(c) (d)

1Q INDUCTION MOTOR

Split phase motor Repulsion motor

Ans d

45. For a given out put at rated rpm, a Ans d universal motor will requires least voltage (a) At 60Hz 39. In repulsion motor by shifting the position (b) At 50Hz of brushes (c) At 25Hz (a) Only speed can be controlled (d) At D.C voltage (b) Speed and direction of rotation can be controlled Ans d (c) Speed direction of rotation and torque 46. The motor used on small lathe is usually can be controlled (a) 3Q synchronous motor (d) None of the above (b) D.C shunt motor Ans b (c) Single phase capacitor run motor capacitor start 40. Which of the following 1Q induction (d) Universal motor reversible (a) Reluctance motor Ans c (b) Resistance start split phase motor 47. Which of the following is the unexcited (c) Capacitor start split phase motor 1Q synchronous motor (d) None of the above (a) Reluctance motor Ans c (b) Universal motor (c) A.C series motor 41. For which of the following application, a (d) Repulsion motor reluctance motor is preferred (a) Single and timing devices Ans a (b) Refrigerator 48. Split phase motors are commonly (c) Lift and hoists available in size (d) Electric shaver (a) ½ HP to 1/3 HP Ans a (b) ½ to 2 HP (c) 1 HP to 5 HP 42. R.P.M of 2 pole hysteresis motor on 60 (d) Above 5HP Hz supply will be (a) 120 rpm Ans a (b) 1500 rpm 49. Which of the following motor is preferred (c) 1800 rpm for tape recorder (d) 3600 rpm (a) Shaded pole motor Ans d (b) Two value capacitor motor (c) Hysteresis motor 43. In a repulsion motor (d) Universal motor (a) The speed remain constant (b) The speed variation with in 5% Ans c (c) Speed vary with load 50. For which of the following appli cation on (d) Speed vary only with change in two value capacitor motor is preferred in supply voltage (a) Toys Ans c (b) Refrigerator (c) Electric shaver 44. In single phase repulsion motor the P.F is (d) Record players (a) Always unity (b) Always loading Ans b (c) High at low speed 51. A single phase inductance motor is (d) High at high speed (a) Always unity (b) Always loading Page 4

OBJECTIVE ELECTRICAL ENGINEERING

(c) (d)

1Q INDUCTION MOTOR

High at low speed High at high speed

Ans b

58. A single phase induction motor is Ans d (a) In herently self starting with high torque 52. For a given out put at rated rpm, a (b) In herently self starting with low universal motor will requires least voltage torque (a) At 60 Hz (c) In herently non self starting with low (b) At 50 Hz torque (c) At 25 Hz (d) In herently non self starting with high (d) At D.C voltage torque Ans d

Ans c

53. The motor used on small lathe is usually (a) 3Q synchronous motor (b) D.C shunt motor (c) Single phase capacitance run motor and capacitance start (d) Universal motor Ans c 54. Which of the following is it unexcited 1Q synchronous motor (a) Reluctance motor (b) Universal motor (c) A.C series motor (d) Repulsion motor Ans a

59. A charger motor can be sum on (a) Slip (b) Negative slip (c) Positive slip (d) All of the above Ans d 60. The speed of standard split phase motor is nearly same as that of (a) Universal motor (b) 3Q induction motor (c) Synchronous motor (d) D.C series motor Ans b 61. In a capacitance start motor any reduction in the value of capacitance is likely to result is reduced (a) Rpm (b) Vibration (c) Speed (d) Starting torque

55. Split phase motors are commonly available in sizes (a) ½ HP to 1/3 HP (b) ½ to 2 HP (c) 1 HP to 5 HP (d) Above 5 HP Ans a

Ans d

56. Which of the following motor is preferred for tape recorder (a) Shaded pole motor (b) Two value capacitance motor (c) Hysteresis motor (d) Universal motor Ans c

62. Which of the following is not necessary the characteristic of a shaded pole motor (a) Low starting torque (b) High P.F (c) Large slip (d) Poor efficiency Ans b

57. For which of the following application a two a value capacitance motor is preferred in (a) Toys (b) Refrigerator (c) Electric shaver (d) Recorder players

63. A universal motor can run on (a) A.C supply only (b) D.C supply only (c) Either A.C or D.C supply (d) None of the above Ans c 64. Which of the following 1Q motor is

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OBJECTIVE ELECTRICAL ENGINEERING

1Q INDUCTION MOTOR

suitable for timing and controlled purpose (a) Universal motor (b) Series motor (c) Repulsion motor (d) Reluctance motor Ans d 65. A universal motor can be operated on 220 volt D.C as well as 220 volt A.C which of the following will be the same in two cases (a) Operating speed (b) Power out put (c) Operating speed as well as out put (d) None of the above Ans c 66. In case a D.C series motor is connected to A.C supply of the same rpm value it is likely to result in (a) Burning of winding (b) Dangerous high speed operating (c) Leading power fector(P.F) (d) Excessive spacking and poor efficiency Ans d 67. In case of shaded pole motor the direction of rotation of the motor is (a) From shaded pole to main pole (b) From main pole to shaded pole (c) Either of the depending of voltage (d) None of above Ans b 68. Which of the following is not valid in case of repulsion motor (a) High P.F (b) Sparking at brushes (c) High speed on no load (d) Speed variation proportional in load Ans a 69. The speed variation of split phase motor between no load and fu ll load condition is (a) 0.2% to 0.5% (b) 2% to 5% (c) 10% to 20% (d) 20% to 30%

(a) (b) (c) (d)

Over load Worn out bearing High voltage Shorted winding Ans c

71. All of the following are not found in shaded pole motor, except (a) Centrifugal switch (b) Rotor (c) Commutator (d) Capacitor Ans b 72. In case of high speed universal motor, which of the following needs more attention (a) Insulation in rotor (b) Air gap (c) Balancing of rotor (d) End plates Ans c 73. The wattage rating of a ceiling fan motor will be in the range of (a) 10-20 watt (b) 50-150 watt (c) 250-500 watt (d) 500-750 watt Ans b 74. The wattage of motor for driving domestic sewing machine will be around (a) 5-10 watt (b) 10-30 watt (c) 40-80watt (d) 100-150 watt Ans d 75. The motor for which of the following application will have the least wattage (a) Mixer gwinding (b) Table fan (c) Electric shaver (d) Exhaust fan Ans c

76. Which of the following single phase motor has relatively poor starting torque (a) Repulsion motor Ans b (b) Universal motor 70. All of the following causes of operating of (c) Capacitor motor a single phase motor except Page 6

OBJECTIVE ELECTRICAL ENGINEERING

(d)

1Q INDUCTION MOTOR

All 1Q motors have 0 starting torque Ans c

77. The capacitor select of capacitor run motor should be rated for (a) Peach value of voltage (b) Rpm value of voltage (c) D.C value of voltage (d) Average value of voltage

83. When a D.C series motor is connected to A.C supply excessive eddy current will be produced in (a) Yoke (b) Yoke and field core (c) Yoke, field core and stator (d) Yoke, field core, stator and rotor shaft Ans b

84. When a D.C series motor is connected to A.C supply the power fector(P.F) will be low because of 78. Which of the following is effered b y crans (a) High inductance of field and armature and hoists circuit (a) Gradual varing load (b) Induced current in rotor due to (b) None reversing no load start variation of flux (c) Reversing light start (c) Fine copper wire winding (d) Reversing heaving start (d) None of the above Ans d Ans a 79. The speed of universal motor is generally 85. The direction of rotation of universal reduce by using motor can be reversal by reversing the (a) V-blots flow of current through (b) Geartaroin (a) Armature winding (c) Break (b) Field winding (d) Chain (c) Either armature as field winding (d) None of the above Ans b Ans a

80. H.R.C fuse in the line for a 1Q motor provided best protection against (a) Open circuit (b) Short circuit (c) Over load (d) Voltage fluctuation Ans b

Ans c 86. Which universal motor is used for low horse power rating (a) Concentrated pole, non compensated type (b) Distributed field compensated type (c) Either a or b of above (d) None of the above

81. Which of the following motor can be used Ans a for unity P.F (a) Shaded pole motor 87. In which single phase motor the rotor has (b) Capacitor run motor no teeth or winding (c) Schrage motor (a) Reluctance motor (d) Hysteresis motor (b) Split phase motor (c) Hysteresis motor Ans c (d) Universal motor 82. The speed load characteristic of universal Ans c motor closely resemble the characteristic of which of the following motor 88. Which motor is normally free from (a) Capacitor start motor mechanical and magnetic vibration (b) Shaded start motor (a) Universal motor (c) 3Q induction motor (b) Split phase motor (d) None of the above (c) Shaded pole motor (d) Hysteresis motor Ans d Page 7

OBJECTIVE ELECTRICAL ENGINEERING

1Q INDUCTION MOTOR

Ans d

(d)

89. As hysteresis motor are free from mechanical and magnetic vibration, there for these are considered as suitable for (a) Fan (b) Blower (c) Mixer grinder (d) Sound equipment

None of the above Ans c

96. The electric motor is used in portable drill (a) Universal motor (b) Capacitor run motor (c) Repulsion motor (d) Hysteresis motor Ans a

Ans d

97. Which of the following application, always have some load, when ever switched on (a) Fan motor (b) Vaccume cleaner (c) Pistol drill (d) All of the above

90. A reluctance motor (a) Is self starting (b) Is constant speed motor (c) Needs no D.C exciatation (d) All of the above Ans d

Ans d

91. Reluctance motor can be used for (a) Recording instruments (b) Timer (c) Single devices (d) Any of the above

98. In pistol drill gear train is used to (a) Vary the speed (b) Reduce the speed (c) Increase the speed (d) Change the direction of rotation

Ans d

Ans b

92. In a hysteresis motor, the rotor must have 99. The speed control of universal motor high used for sewing machine is by (a) Resistivity (a) Varying the resistance (b) Rentitivity (b) Friction (c) Suspetablity (c) Centrifugal machenizam (d) None of the above (d) Tapping the field Ans b Ans a 93. The rotor of hysteresis motor is made of 100. In a capacitor start capacitor run (a) Cast iron motor the two capacitor (b) Aluminium (a) Have similar construction (c) Crome steel (b) Are of different type (d) Copper (c) Have equal capacitor Ans c (d) None of the above 94. Because of high rentitivity of the rotor of Ans b hysteresis motor 101. The motor generally used in house (a) Eddy current loss is high hold mixer is (b) Eddy current loss is low (a) Shaded pole motor (c) Hysteresis loss is low (b) Universal motor (d) Hysteresis loss is high (c) Capacitor start motor Ans d (d) None of the above 95. In a universal motor on no load the speed Ans b is limited by 102. The cheapest motor in the (a) Voltage fractional horse power motor is (b) Current flow (a) Split phase motor (c) Friction and windage load Page 8

OBJECTIVE ELECTRICAL ENGINEERING

(b) (c) (d)

1Q INDUCTION MOTOR

Capacitor start motor Shaded pole motor None of the above

Ans c

Ans c 103. As compare to split phase motor a capacitor start motor has (a) Higher starting torque (b) Lower starting torque (c) Higher running torque (d) None of the above Ans a 104. The capacitor motor is generally used for exhaust fan because (a) It has higher full load efficiency(n) (b) It has high starting torque (c) It has low running torque (d) All of the above Ans d 105. A loss in the capacitance of a capacitor start motor result in reduces (a) Speed (b) Voltage (c) Armature reaction (d) Starting torque Ans d 106. on (a) (b) (c) (d)

Which type of starting relay used 1Q hermetic is Hot wire relay Timing relay Current coil relay None of the above Ans d

107. A loss in the capacitance of a capacitance start motor result in reduces (a) Speed (b) Voltage (c) Armature reaction (d) Starting torque Ans d 108. on (a) (b) (c) (d)

Which type of starting relay used 1Q hermetic is Hot wire relay Timing relay Current coil relay None of the above

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109. Which of the following application may use of universal (a) Floor polishing machine (b) Oil expeller machine (c) Portable tools (d) Lethe machine Ans c 110. The direction of rotation of a universal motor can be reversed by (a) Reversing the supply terminal (b) Switch over from A.C to D.C (c) Inter canging the brush loads (d) Any of the above Ans c 111. A 1Q motor us generally used for small air compressure is (a) Capacitor start capacitor run motor (b) Reluctance motor (c) Universal motor (d) Shaded pole motor Ans a 112. By pushing and peling the rotor shaft of a motor we can check its (a) Firm ness of mounting (b) Free shaft movement (c) End play (d) Side play Ans c 113. In a two value capacitor motor the capacitor is used for running purpose is (a) Dry type A.C electrolytic capacitor (b) Paper spaced oil filled type (c) An air capacitor (d) Ceramic type capacitor Ans b 114. at (a) (b) (c) (d)

Universal motors are designed run using high speed so that Operating P.F is good Efficiency is better It produce more torque Cooling is better Ans a

115. Which motor is used for rocket (a) Permanent magnet type (b) Shaded pole motor

OBJECTIVE ELECTRICAL ENGINEERING

(c) (d)

1Q INDUCTION MOTOR

Universal motor Reluctance motor

122. The direction of rotation a repulsion motor any be reversed by (a) Reversing the direction of brushes (b) Reversing the supply terminals (c) Reversing the field winding (d) None of the above Ans a 123. Speed of a repulsion motor on no load is (a) Very low (b) Low (c) High (d) Dangersously high

Ans a 116. Which of the following single phase motor mostly used for photo copying machine (a) Shaded pole motor (b) Schrage motor (c) Reluctance motor (d) Universal motor Ans a 117. The stator rotor pole no.may be different in a (a) Pole changing induction motor (b) Reluctance motor (c) Repulsion motor (d) Synchronous motor Ans b 118. In hand application single phase motor used is (a) Shaded pole motor (b) Capacitor start motor (c) Capacitor run motor (d) A.C series motor Ans d 119. A capacitor start single phase motor is used (a) For easy to start loads (b) For medium start loads (c) For hard to start loads (d) For any type to start loads Ans c 120. Which of the following 1Q motor is used for hair dryer (a) Shaded pole motor (b) Capacitor start capacitor run (c) Reluctance motor (d) Universal motor Ans a 121. (a) (b) (c) (d)

Speed of universal motor is Depends on supply frequency Proportional to supply frequency Independent of supply frequency None of the above Ans a Page 10

Ans d 124. Single phase induction motor capacitor start capacitor run motor basically is (a) 1Q motor (b) Two phase motor (c) A.C series motor (d) None of the above Ans b 125. The direction of rotation of a shaded pole motor is (a) From mouth to south pole (b) From south pole to north pole (c) From unshaded part to shaded part (d) From shaded part to unshaded part Ans c 126. The fector controlling speed of a shaded pole motor directly is (a) Current (b) Rotor losses (c) Impresses voltage (d) None of the above Ans c 127. Maximum starting torque is developed in repulsion motor the brush position is respect to the pole axis is (a) 00 0 (b) 180 0 (c) 90 0 (d) 45 Ans d 128. The rotor core of a hysteresis motor is made of (a) Hardend silicon steel rings (b) Thin silicon steel lamination

OBJECTIVE ELECTRICAL ENGINEERING

(c) (d)

1Q INDUCTION MOTOR

Cast iron Copper iron most Ans a

129. Which type of motor is most suitable for a computer printer drive (a) Reluctance motor (b) Hysteresis motor (c) Shaded pole motor (d) Stepper motor Ans d

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