Recent questions tagged motors

asked Sep 3, 2019 by anonymous

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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138 views 1 answer

asked Aug 17, 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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36 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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66 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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1.2k views 2 answers

asked Jul 30, 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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2.4k 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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66 views 1 answer

asked Jul 24, 2019 by ZAHID

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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2.5k views 0 answers

asked May 8, 2018 by anonymous

A relay used for protection of motors against overload is :

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: A relay used for protection of motors against overload is : Thermal relay

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242 views 1 answer

asked Apr 29, 2018 by anonymous

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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69 views 1 answer

asked Apr 29, 2018 by anonymous

Stepper motors are used in

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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48 views 1 answer

asked Apr 29, 2018 by anonymous

Which of the following motors can run on both AC and DC?

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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115 views 1 answer

asked Apr 28, 2018 by anonymous

Slot harmonics are reduced in induction motors by using

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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61 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

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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78 views 1 answer

asked Apr 28, 2018 by anonymous

Which of the following test is usually conducted to determine the efficiency of traction motors ?

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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209 views 1 answer

asked Apr 26, 2018 by anonymous

Which of the following motors is being extensively used in servo applications ?

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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148 views 1 answer