Last Answer : In a capacitor start single-phase motor, when capacitor is replaced by a resistance motor will continue to run in same direction.
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223 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to improve power factor.
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710 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The capacitors used in single-phase capacitor motors have no polarity marking.
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133 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : If the capacitor of a single-phase motor is short-circuited the motor will not start.
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104 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a capacitor start motor, the phase displacement between starting and running winding can be nearly 90°.
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207 views
1 answer
asked
Mar 20, 2018
by
anonymous

Explain the working of a single phase capacitor start induction motor.
Last Answer : Single phase capacitor start induction motor https://youtu.be/31lvvzU5Puc
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395 views
2 answers
asked
Jul 30, 2019
by
anonymous

Last Answer : To reverse the direction of rotation of a capacitor 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.
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131 views
1 answer
asked
Mar 20, 2018
by
anonymous

A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will?
Last Answer : A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will not start at all.
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231 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : A single-phase induction motor is inherently non-self-starting with low torque.
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73 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The power factor of a single-phase induction motor is usually lagging.
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189 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.
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204 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The rotor developed by a single-phase motor at starting is zero.
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89 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The range of efficiency for shaded pole motors is 5% to 35%.
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120 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The repulsion-start induction-run motor is used because of high starting torque.
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89 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : In a two value capacitor motor, the capacitor used for running purposes is paper spaced oil filled type.
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162 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : The value of starting capacitor of a fractional horse power motor will be 300 uF .
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98 views
1 answer
asked
Mar 20, 2018
by
anonymous
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SINGLE PHASE INDUCTION MOTORS MCQ
Last Answer : 101. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on (a) running winding (b) rotor winding (c) field winding (d) compensating winding Ans: a ... motor is usually reduced by using (a) gearing (b) belts (c) brakes (d) chains Ans: a
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22 views
3 answers

What are the five types of single phase motors used in the industry?
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79 views
0 answers
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Mar 15, 2018
by
anonymous

Why is a capacitor used in a single phase motor and not in three phase motor ?
Last Answer : In 1-phase induction motor capacitor work is generate the auxiliary winding current than excite the main winding to rotor starts rotate. After rotor start rotating about 75% of their speed than auxiliary ... emf to start the motor.so,in 3-phase induction motor is self start induction motor.
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260 views
6 answers
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Sep 2, 2019
by
anonymous

THREE PHASE INDUCTION MOTORS MCQ
Last Answer : 101. Insertion of resistance in the stator of an induction motor (a) increases the load torque (b) decreases the starting torque (c) increases the starting torque (d) none of the above Ans: b
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323 views
3 answers

3 phase motor 42 hp same ratting two motors but pole change 2 and 4 pole tell me difference amp of both motors
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2.6k views
0 answers
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Jul 24, 2019
by
ZAHID

Damper winding is provided in 3 phase synchronous motors to :
Last Answer : Damper winding is provided in 3 phase synchronous motors to : provide starting torque and prevent hunting
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93 views
1 answer
asked
Apr 29, 2018
by
anonymous

Single-phase mid-point controlled rectifier with RL load
Last Answer : Single-phase mid-point controlled rectifier with RL load : The circuit configuration of single-phase midpoint controlled rectifier is shown in the figure. During positive half-cycle of ... some part of next positive half-cycle of voltage with reversed polarity can appear across load.
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209 views
1 answer
asked
Oct 13, 2019
by
anonymous

Single-phase Midpoint controlled rectifier with Resistive load
Last Answer : Single-phase Midpoint controlled rectifier with Resistive load: 1) During positive half cycle of AC supply, a is positive with respect to b , this makes T1 forward biased and T2 is reverse ... voltage reverses the polarity and T2 is turned off. The operation is as shown in waveforms.
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612 views
1 answer
asked
Oct 13, 2019
by
anonymous
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When the firing angle a of a single-phase, fully controlled rectifier feeding constant direct current into a load is 30°, the displacement power factor of the rectifier is
Last Answer : When the firing angle a of a single-phase, fully controlled rectifier feeding constant direct current into a load is 30°, the displacement power factor of the rectifier is √3/2
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1.4k views
1 answer
asked
Apr 29, 2018
by
anonymous

An additional condition for parallel operation of three-phase transformers over single-phase transformers is that
Last Answer : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that the transformers should belong to the same vector group
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144 views
1 answer
asked
Apr 29, 2018
by
anonymous

In a single-phase induction motor, the operating direction is determined by the ________ A) Rotor B) Stator C) Starting circuit D) None of these
Last Answer : In a single-phase induction motor, the operating direction is determined by the Starting circuit
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128 views
1 answer
asked
Apr 29, 2018
by
anonymous

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α
Last Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ
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150 views
1 answer
asked
Apr 28, 2018
by
anonymous

A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is (A) 4.5 V (B) 6.75 V (C) 9 V (D) 13.5 V
Last Answer : A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is 9 V
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182 views
1 answer
asked
Apr 28, 2018
by
anonymous

In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is (A) sinusoidal current (B) constant dc current (C) continuous rectangular pulses (D) alternating rectangular pulses
Last Answer : In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is alternating rectangular pulses
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177 views
1 answer
asked
Apr 28, 2018
by
anonymous

The sequence components of current of a single-phase load connected to a 3-phase system are (A) equal positive and negative sequence components (B) equal positive, negative and zero sequence components (C) vector sum of sequence currents is zero (D) algebraic sum of sequence currents is zero
Last Answer : The sequence components of current of a single-phase load connected to a 3-phase system are equal positive, negative and zero sequence components
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478 views
1 answer
asked
Apr 28, 2018
by
anonymous

In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then (A) the flux is constant (B) the flux first decreases and then increases in ... increases and decreases in the opposite direction with the same magnitude (D) current flows through the rotor
Last Answer : In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then the flux first decreases and then increases in the same direction
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95 views
1 answer
asked
Apr 28, 2018
by
anonymous

A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is (A) 216 V (B) 226 V (C) 234 V (D) 236 V
Last Answer : A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is 226 V
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139 views
1 answer
asked
Apr 28, 2018
by
anonymous

In a single-phase transformer, the magnetizing current is (A) in phase with the no-load current (B) in quadrature with the no-load current (C) the product of no-load current and power factor (D) in phase with the flux in the core
Last Answer : In a single-phase transformer, the magnetizing current is in phase with the flux in the core
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86 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : The starting winding of a single-phase motor is placed in stator.
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115 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : If starting winding of a single-phase induction motor is left in the circuit, it will draw excessive current and overheat.
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234 views
1 answer
asked
Mar 20, 2018
by
anonymous

SYNCHRONOUS MOTORS MCQ
Last Answer : 101. In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then (a) the motor is said to be fully loaded (b) the torque ... square of the applied voltage (c) inversely proportional to applied voltage (d) none of the above Ans: a
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19 views
3 answers

Why are DC motors used in trains and not AC motors ?
Last Answer : The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.
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161 views
1 answer
asked
Sep 3, 2019
by
anonymous

Suggest electric motors for i) traction ii) crane iii) lathe machine iv) domestic fan.
Last Answer : i) Traction :- DC Series motor ii) Crane :- DC Series motor iii) Lathe machine :- 3 phase Induction motor or DC shunt motor iv) Domestic fan :- 1 phase induction motor
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74 views
1 answer
asked
Aug 17, 2019
by
anonymous

State which electric motors are generally used in electro agro systems with reason.
Last Answer : 1) 3 phase induction motor is used in electro agro system for water pumping from wells as 3 phase ac supply is easily available, cost of induction motor is less, maintenance free being rugged ... as 1 phase ac supply is easily available for domestic purpose, repair is simple and easily available.
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94 views
1 answer
asked
Aug 17, 2019
by
anonymous

State factors for selection of motors as drive.
Last Answer : Following Factors governing / or are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- ... level, load equalization 7) Cost: - Capital, Running and maintenance cost should be less.
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1.9k views
2 answers
asked
Aug 17, 2019
by
anonymous

Compare variable reluctance and permanent magnet motors.
Last Answer : Variable reluctance Motor Permanent magnet motors The rotor is not magnetised The rotor is magnetised High torque to inertia ratio Low torque to inertia ratio ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction.
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2.5k views
1 answer
asked
Jul 30, 2019
by
anonymous

What are the factors to be considered while selection of motors for different drives?
Last Answer : Following Factors are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- Whether supply ... , load equalization 7) Cost: - Capital, Running and maintenance cost should be less.
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140 views
1 answer
asked
Jul 30, 2019
by
anonymous

A relay used for protection of motors against overload is : (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay
Last Answer : D
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547 views
2 answers
asked
May 8, 2018
by
anonymous

Stepper motors are used in (1) printers (2) lifts (3) amplifiers (4) oscillators
Last Answer : Stepper motors are used in printers
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68 views
1 answer
asked
Apr 29, 2018
by
anonymous
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Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
Last Answer : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
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179 views
1 answer
asked
Apr 29, 2018
by
anonymous
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Slot harmonics are reduced in induction motors by using (A) fractional-pitch windings (B) fractional-slot windings (C) integral-slot windings (D) distributed windings
Last Answer : Slot harmonics are reduced in induction motors by using fractional-slot windings
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79 views
1 answer
asked
Apr 28, 2018
by
anonymous

Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as (A) One-third of their synchronous speed (B) One-fifth of their synchronous speed (C) One-seventh of their synchronous speed (D) One-ninth of their synchronous speed
Last Answer : Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as One-seventh of their synchronous speed
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102 views
1 answer
asked
Apr 28, 2018
by
anonymous

Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.
Last Answer : Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.
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248 views
1 answer
asked
Apr 28, 2018
by
anonymous

Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these
Last Answer : Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these
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203 views
1 answer
asked
Apr 26, 2018
by
anonymous
