Why Induction motors are widely used in Industries?

Why Induction motors are widely used in Industries?
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1 Answer

Answer :

Answer: In Industries 80% of the motor drives used are induction motors. Induction Motors are widely used in Industries because of some features it possess.
They are:
• Low Cost
• Simple and Rugged Construction
• Absence of Commutator
• Good power factor
• Higher efficiency
• Good Speed Regulation
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Related questions

Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency? A. A four-pole synchronous motor under normal load. B. A four-pole induction motor under no load. C. A six-pole synchronous motor under normal load. D. A six-pole induction motor under full load.

Description : Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency? A. A four-pole synchronous motor under normal load. B. A four-pole induction motor under ... A six-pole synchronous motor under normal load. D. A six-pole induction motor under full load.

Last Answer : Answer: A

The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and _____________. A. decreased motor magnetizing current B. hysteresis loses C. increased power factor D. mechanical damage to the rotor

Description : The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and _____________. A. decreased motor magnetizing current B. hysteresis loses C. increased power factor D. mechanical damage to the rotor

Last Answer : Answer: D

Most three-phase induction motors of five horsepower or less, are started by _____________. A. autotransformer starters B. resistor starters C. across-the-line starters D. reactor starters

Description : Most three-phase induction motors of five horsepower or less, are started by _____________. A. autotransformer starters B. resistor starters C. across-the-line starters D. reactor starters

Last Answer : Answer: C

Most three-phase induction motors used for driving engine room auxiliaries are started by _____________. A. resistor starters B. across-the-line starters C. impedance starters D. reactor starters

Description : Most three-phase induction motors used for driving engine room auxiliaries are started by _____________. A. resistor starters B. across-the-line starters C. impedance starters D. reactor starters

Last Answer : Answer: B

Which of the following types of motors is often designed for use in correcting power factor? A. Polyphase B. Wound-rotor C. Induction D. Synchronous

Description : Which of the following types of motors is often designed for use in correcting power factor? A. Polyphase B. Wound-rotor C. Induction D. Synchronous

Last Answer : Answer: D

Autotransformer starters or compensators are sometimes used with polyphase induction motors to _____________. A. reduce the voltage applied to the motor during the starting period B. increase the voltage for 'across-the-line starting' C. provide a backup means of voltage regulation for emergency starting D. allow the voltage to be either stepped up or down, depending on the application, to ensure full torque

Description : Autotransformer starters or compensators are sometimes used with polyphase induction motors to _____________. A. reduce the voltage applied to the motor during the starting period B. increase the voltage for ' ... to be either stepped up or down, depending on the application, to ensure full torque

Last Answer : Answer: A

In general, polyphase induction motors can be started on full line voltage by means of ______________. A. compensator starters B. autotransformer starters C. across-the-line starters D. primary-resistor starters

Description : In general, polyphase induction motors can be started on full line voltage by means of ______________. A. compensator starters B. autotransformer starters C. across-the-line starters D. primary-resistor starters

Last Answer : Answer: C

Low horsepower, polyphase, induction motors can be started with full voltage by means of _____________. A. compensator starters B. autotransformer starters C. across-the-line starters D. primary-resistor starters

Description : Low horsepower, polyphase, induction motors can be started with full voltage by means of _____________. A. compensator starters B. autotransformer starters C. across-the-line starters D. primary-resistor starters

Last Answer : Answer: C

Slip ring induction motor advantages and disadvantages compared to squirrel cage motors?

Description : Slip ring induction motor advantages and disadvantages compared to squirrel cage motors?

Last Answer : Advantages: High starting torque with low starting current Smooth acceleration under heavy loads No abnormal heating during starting Good running characteristics after external rotor resistances are cut out ... cage motors The speed regulation is poor when run with resistance in the rotor circuit

What are the advantages and disadvantages of Induction Motors?

Description : What are the advantages and disadvantages of Induction Motors?

Last Answer : Advantages: It is simple and rugged in construction It is relatively cheap Induction motors require less maintenance Induction motor has high efficiency and reasonably good power factor 3-phase induction ... and its speed cannot be changed easily Its starting torque is inferior to dc shunt motor

Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Description : Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Last Answer : Capacitors are easily available, cheaper and reliable. Repulsion-induction motors posses a special commutator and brushes that require maintenance. Most manufacturers have stopped making them.

Why capacitor –start induction motors advantageous?

Description : Why capacitor –start induction motors advantageous?

Last Answer : In capacitor start induction motors capacitor is connected in series with the auxiliary winding. When speed of the motor approaches to 75 to 80% of the synchronous speed the starting winding gets ... torque is proportional to phase angle ά and hence such motors produce very high starting torque.

Give applications of Capacitor start Induction run motors.

Description : Give applications of Capacitor start Induction run motors.

Last Answer : Drilling machine, centrifugal pump, grinders , refrigerator etc

Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Description : Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Last Answer : Ans : Capacitors are easily available, cheaper and reliable. Repulsion-induction motors posses a special commutator and brushes that require maintenance. Most manufacturers have stopped making them.

Why are centrifugal switches provided on many 1-phase Induction motors?

Description : Why are centrifugal switches provided on many 1-phase Induction motors?

Last Answer : Centrifugal switches are provided on many 1-phase Induction motors to disconnect the starting / auxiliary winding from the supply when the motor reaches about 70% of its synchronous speed.

Name types of 1-phase induction motors.

Description : Name types of 1-phase induction motors.

Last Answer : Based on the method of starting arrangement provided, the 1-phase Induction motors are classified as follows (i) Split-phase motor (ii) Shaded pole motor (iii) Resistor start Induction run ... iv) capacitor start Induction run single phase IM (v) capacitor start Capacitor run single phase IM

Name the two different theories with which principle of 1-phase induction motors are explained

Description : Name the two different theories with which principle of 1-phase induction motors are explained

Last Answer : The two different theories are · Double revolving field theory · Cross field theory

Where do we require single-phase induction motors?

Description : Where do we require single-phase induction motors?

Last Answer : Single-phase induction motors are required where (i) 3 phase supply is not available (ii) Efficiency is of lesser importance (iii) Rating is less than one H.P. (iv) Equipment is portable

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Last Answer : The answer is 'Bacteria,microalgae and fungi.'

Which type of microorganism is most widely used in industries? -General Knowledge

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Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of (A) Bronze (B) Stainless steel (C) Flint or porcelain (D) Concrete

Description : Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of (A) Bronze (B) Stainless steel (C) Flint or porcelain (D) Concrete

Last Answer : (C) Flint or porcelain

Laser welding is widely employed in the __________ industries. (A) Electronic (B) Structural (C) Process (D) Heavy

Description : Laser welding is widely employed in the __________ industries. (A) Electronic (B) Structural (C) Process (D) Heavy

Last Answer : Option A

Laser welding is widely employed in the __________ industries. (A) Electronic (B) Structural (C) Process (D) Heavy

Description : Laser welding is widely employed in the __________ industries. (A) Electronic (B) Structural (C) Process (D) Heavy

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Description : Which type of microorganism is most widely used in industries?

Last Answer : Bacteria, microalgae and fungi

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Description : _________is the most widely used media in distribution of heat over distance in industries a) Steam b) light c) Springs c) water

Last Answer : a) Steam

How to control the speed of induction motors? Do variable frequency drives plays a role in that?

Description : How to control the speed of induction motors? Do variable frequency drives plays a role in that?

Last Answer : VSD - DC/DC usage to drive compressors allows controlling and accurate measurements on speed and torque of compressor motors, and so enhancing its application characteristics. Integrating of VSD ... vital auxiliary circuit. The converter is analyzed; design and considerations have been discussed.

Straight silicon steel (containing Si from 0.5 to 5%) because of their low hysteresis loss and high magnetic permeability are used for electrical appliances. Which of the following electrical appliances made of silicon steel contains maximum percentage of silicon (about 4%)? (A) Armature of small motors/generators (B) Generators and small motors (C) Induction motors (D) High frequency transformers

Description : Straight silicon steel (containing Si from 0.5 to 5%) because of their low hysteresis loss and high magnetic permeability are used for electrical appliances. Which of the following electrical ... /generators (B) Generators and small motors (C) Induction motors (D) High frequency transformers

Last Answer : (D) High frequency transformers

On which Following products is labelling not Voluntary a) Colour TV c) Ceiling fans b) Ballast d) Induction motors

Description : On which Following products is labelling not Voluntary a) Colour TV c) Ceiling fans b) Ballast d) Induction motors

Last Answer : Colour TV

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Description : Products on which labeling is voluntary are a) Electric geysers b) Induction motors b) Ceiling fans d) All of the above

Last Answer : All of the above

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Description : How do split-phase induction motors become self-starting?

Last Answer : By using combinations of inductance and capacitance to apply out-of phase currents in starting windings.

In induction motors, the length of air gap in kept as small as mechanically possible is order to have (a) low power factor (b) high power factor (c) high over load capacity (d) any of the above

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Last Answer : (b) high power factor

SINGLE PHASE INDUCTION MOTORS MCQ

Description : 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

THREE PHASE INDUCTION MOTORS MCQ

Description : 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

State the types of single phase induction motors.

Description : State the types of single phase induction motors.

Last Answer : The types of single phase induction motors are: i) Resistance split phase induction motor. ii) Capacitor split phase inductor motor. a. Capacitor start induction run motor b. permanent capacitor motor c. capacitor start capacitor run induction motor iii) Shaded pole induction motor.

What is the effect of following on induction motors: (1) Voltage unbalance (2) Harmonic distortion

Description : What is the effect of following on induction motors: (1) Voltage unbalance (2) Harmonic distortion

Last Answer : i) Effect of voltage unbalance: For three phase motors this leads to unequal currents in the three phase windings that result in unbalance in the fields produced due to which negative phase ... currents thereon). This leads to motor failures, lower life and improper torque speed characteristics. 

State the classification of single phase induction motors.

Description : State the classification of single phase induction motors.

Last Answer : Types of single phase induction motors: 1. Split phase induction motor. 2. Capacitor start inductor motor. 3. Capacitor start capacitor run induction motor. 4. Permanent split capacitor motor. 5. Shaded pole induction motor. 

The speed and torque of induction motors can be varied by which of the following means:

Description : The speed and torque of induction motors can be varied by which of the following means: 1) Stator voltage control 2) Rotor voltage control 3) Frequency control 4) All of these

Last Answer : All can off them can control speed and torque of induction motor.This is because  increased supply frequency increases synchronous speed  which will definetly affect torque and speed . .Both stator and rotor  voltage control are proportional to torque and slip.

Deep bar rotor construction is used in three phase induction motors to mainly:

Description : Deep bar rotor construction is used in three phase induction motors to mainly: (1) Control speed (2) Control power factor (3) Increase starting torque (4) None of these

Last Answer : Deep bar rotor construction is used in three phase induction motors to mainly: Increase starting torque

In the Squirrel cage induction motors, the rotor slots are usually a slight skew to reduce

Description : In the Squirrel cage induction motors, the rotor slots are usually a slight skew to reduce (A) Windage losses (B) Eddy currents (C) Accumulation of dirt and dust (D) Magnetic hum

Last Answer : Eddy   currents.

Slot harmonics are reduced in induction motors by using

Description : 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

Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as

Description : 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

Unless it can be shown that a 45°C ambient temperature will not be exceeded, motors within a machinery space must be designed for an ambient temperature of _____________. A. 45°C B. 50°C C. 55°C D. 60°C

Description : Unless it can be shown that a 45°C ambient temperature will not be exceeded, motors within a machinery space must be designed for an ambient temperature of _____________. A. 45°C B. 50°C C. 55°C D. 60°C

Last Answer : Answer: B

As shown in the illustration, the electrical symbol is used to indicate which of the listed types of motors? EL-0054 A. Shunt motor. B. Series motor. C. Compound motor. D. Tri-field motor.

Description : As shown in the illustration, the electrical symbol is used to indicate which of the listed types of motors? EL-0054 A. Shunt motor. B. Series motor. C. Compound motor. D. Tri-field motor.

Last Answer : Answer: C

An advantage of DC motors over AC motors is that they _____________. A. are less expensive B. require less maintenance C. offer infinite speed variation D. all of the above

Description : An advantage of DC motors over AC motors is that they _____________. A. are less expensive B. require less maintenance C. offer infinite speed variation D. all of the above

Last Answer : Answer: C

Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while starting. C. The brushes are removed from the commutator while starting. D. They have a low starting torque.

Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.

Last Answer : Answer: B

Universal motors will operate on AC or DC current, and are generally found in _____________. A. portable tools B. large pump motors C. turbo electric main motors D. forced draft fans

Description : Universal motors will operate on AC or DC current, and are generally found in _____________. A. portable tools B. large pump motors C. turbo electric main motors D. forced draft fans

Last Answer : Answer: A

Electric motors intended for use outside the engine room and boiler room are frequently rated to run at a designed ambient temperature of 40°C. What is the equivalent temperature in degrees Fahrenheit? A. 54.2°F B. 72.0°F C. 104.0°F D. 129.6°F

Description : Electric motors intended for use outside the engine room and boiler room are frequently rated to run at a designed ambient temperature of 40°C. What is the equivalent temperature in degrees Fahrenheit? A. 54.2°F B. 72.0°F C. 104.0°F D. 129.6°F

Last Answer : Answer: C

Electrical failures in motors are caused by the breakdown of insulation, which may be caused by _____________. A. penetration of moisture B. accumulation of dirt C. overheating D. all of the above

Description : Electrical failures in motors are caused by the breakdown of insulation, which may be caused by _____________. A. penetration of moisture B. accumulation of dirt C. overheating D. all of the above

Last Answer : Answer: D