Why skewing is done in squirrel cage Induction motor?

Why skewing is done in squirrel cage Induction motor?
by

1 Answer

Answer :

i)    For more uniform torque
ii)   Reduction in noise
iii) To decrease magnetic locking tendency
by

Related questions

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 of slip ring motor over squirrel cage motor?

Description : What are the advantages of slip ring motor over squirrel cage motor?

Last Answer : 1. The starting torque can be varied by adding resistance to rotor. 2. The speed of the machine can be varied by injecting an emf through slip rings to the rotor.

List out the methods of speed control of cage type 3-phase induction motor?

Description : List out the methods of speed control of cage type 3-phase induction motor?

Last Answer : a) By changing supply frequency b) By changing the number of poles c) By operating two motors in cascade

Can we add extra resistance in series with squirrel cage rotor? State the reason?

Description : Can we add extra resistance in series with squirrel cage rotor? State the reason?

Last Answer : We cannot add extra resistance in series with the rotor because all the copper bars of the rotor are short circuited in both the sides by copper end rings to have a closed circuit.

Explain the operation of induction motor in simple words?

Description : Explain the operation of induction motor in simple words?

Last Answer : Answer: When 3 phase ac supply is given to stator of the induction motor rotating magnetic field will be generated. This magnetic field (flux) cuts the stationary conductors of the rotor of ... be developed. If the torque generated is sufficient to overcome the load torque rotor starts rotating.

Why Speed Control of Induction Motor is difficult compared to DC shunt motor?

Description : Why Speed Control of Induction Motor is difficult compared to DC shunt motor?

Last Answer : Answer: Speed Control of DC shunt motor can be possible by providing resistance in the armature and field circuits and varying the resistors speed changes can be carried out over a wide range. ... employed. Care should be taken that in the process efficiency and power factor should be maintained.

Why the efficiency of the Induction motor is less compared to transformer?

Description : Why the efficiency of the Induction motor is less compared to transformer?

Last Answer : Answer: Induction motor and Transformer operates on the same principle that power is transferred to secondary by mutual induction. But in transformer, flux will be traveled from primary to ... compared to transformer which also results in less efficiency for induction motor compared to transformer.

Disadvantages of Star-Delta Starting of Induction motor?

Description : Disadvantages of Star-Delta Starting of Induction motor?

Last Answer : In Star-Delta starting induction motor stator is connected in star connection for starting after picking up speed it is connected to delta connection. When induction motor is connected in star connection ... . This also results in reduced starting torque (1/3 times compared to delta connection).

What is the condition for maximum torque in induction motor?

Description : What is the condition for maximum torque in induction motor?

Last Answer : Starting torque will be maximum when the rotor resistance / phase is equal to standstill rotor reactance / phase

Induction Motor Operating Characteristics

Description : Induction Motor Operating Characteristics

Last Answer : All torques of an induction motor, at a given slip, vary approximately as the square of the voltage applied to its terminals Low rotor resistance results in high full load speed (low slip), ... voltage), the load torque is unchanged, and the ratio of accelerating torque to load torque is reduced

why the three phase induction motor draws heavy current at starting?

Description : why the three phase induction motor draws heavy current at starting?

Last Answer : At the time of starting, the rotor speed is zero hence slip is 1, the emf induced in rotor winding is very high. Hence rotor current is also very high. The starting current is 5 to 7 times more than its full load current.

What happens if the air gap flux density in an induction motor increases?

Description : What happens if the air gap flux density in an induction motor increases?

Last Answer : The increase in air gap flux increases iron loss and hence efficiency decreases.

What would happen if a 3 phase induction motor is switched on with one phase disconnected?

Description : What would happen if a 3 phase induction motor is switched on with one phase disconnected?

Last Answer : The motor is likely to burn .

In what respect does a 1-phase Induction motor differ from a 3-phase Induction motor?

Description : In what respect does a 1-phase Induction motor differ from a 3-phase Induction motor?

Last Answer : Construction wise a plain 1-phase Induction motor is more or less similar to a 3-phase squirrel-cage Induction motor except that its stator is provided with only 1-phase winding..

Why the air gap of an induction motor is made as small as possible?

Description : Why the air gap of an induction motor is made as small as possible?

Last Answer : The mmf and the magnetizing current are primarily decided by length of air gap. If air gap is small then mmf and magnetizing current will be low, which in turn increase the value of power factor. Hence by keeping small air gap, high power factor is achieved.

List out the methods to improve the power factor of the induction motor.

Description : List out the methods to improve the power factor of the induction motor.

Last Answer : The power factor of the induction motor can be improved by reducing the magnetizing current and leakage reactance. The magnetizing current can be reduced by reducing the length of air gap. The ... stator & rotor slots, by providing short chorded winding and reducing the overhang in stator winding.

What are the advantages and disadvantages of large air gap length in induction motor?

Description : What are the advantages and disadvantages of large air gap length in induction motor?

Last Answer : Advantage: A large air gap length results in higher overload capacity, better cooling, reduction in noise and reduction in unbalanced magnetic pull. Disadvantages: The disadvantage of large air gap length is that it results in high value of magnetizing current.

Which part of induction motor has the maximum flux density? What is the maximum flux density in that part?

Description : Which part of induction motor has the maximum flux density? What is the maximum flux density in that part?

Last Answer : The teeth of the stator and rotor core will have maximum flux density. The maximum value of flux density in the teeth is 1.7 wb/m

What types of slots are preferred for the induction motor?

Description : What types of slots are preferred for the induction motor?

Last Answer : Semi enclosed slots are preferred for induction motor. It results in less air gap contraction factor giving a small value of magnetizing currents, low tooth pulsation loss and much quieter operation(less noise)

What are the different types of stator winding in induction motor?

Description : What are the different types of stator winding in induction motor?

Last Answer : The different types of stator windings are mush winding, lap winding and wave winding.

What are the advantages of 3-phase induction motor?

Description : What are the advantages of 3-phase induction motor?

Last Answer : a) It was very simple and extremely rugged, almost unbreakable construction b) Its cost is very low and it is very reliable c) It has been suffiently high efficiency .No brushes are needed and hence frictional losses are reduced d) It requires minimum of maintenance.

Mention different types of speed control of slip ring induction motor?

Description : Mention different types of speed control of slip ring induction motor?

Last Answer : a) By changing supply frequency b) By changing the number of stator poles c) By rotor rheostat control d) By operating two motors in cascade

Explain why the no load current of an induction motor is much higher than that of an equivalent transformer.

Description : Explain why the no load current of an induction motor is much higher than that of an equivalent transformer.

Last Answer : In induction motor, due to the presence of the air gap, the magnetizing current that is required to set up the flux is much higher. The working component of the current has to meet the ... eddy current loss, friction and windage losses. Hence the no load current of induction motor is higher.

Why the induction motor is called asynchronous motor?

Description : Why the induction motor is called asynchronous motor?

Last Answer : Since the induction motor runs always at a speed lesser than synchronous speed, it is called asynchronous motor.

Why Induction motor is called rotating transformer?

Description : Why Induction motor is called rotating transformer?

Last Answer : Transformer has two sides: primary & secondary. Transformer transforms energy from primary to secondary by induction. Similarly, Induction motor has primary (stator) & secondary (rotor). Voltage is ... magnitude i.e. the process of induction Thus induction motor treated as a rotating transformer.

Name the materials used to insulate the laminations of the core of induction motor.

Description : Name the materials used to insulate the laminations of the core of induction motor.

Last Answer : The materials used to insulate the laminations are kaolin and varnish.

What are the materials used to manufacture the brushes for slip rings of an induction motor?

Description : What are the materials used to manufacture the brushes for slip rings of an induction motor?

Last Answer : A:The slip rings are made of brass and phosphor bronze. The brushes are made of metal graphite which is an alloy of copper and carbon.

What is the purpose of connecting external resistors to slip ring Induction motor?

Description : What is the purpose of connecting external resistors to slip ring Induction motor?

Last Answer : It increases starting torque and decreases starting current.

State the types of Induction motor ?

Description : State the types of Induction motor ?

Last Answer : 1) Squirrel cage Induction motor 2) Wound or slip ring Induction motor.

Squirrel cage induction motor has a) Zero starting torque b) Very small starting torque c) Medium starting torque d) Very high starting torque

Description : Squirrel cage induction motor has a) Zero starting torque b) Very small starting torque c) Medium starting torque d) Very high starting torque

Last Answer : Ans: B

The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit

Description : The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit

Last Answer : Answer: A

A split-phase induction squirrel-cage motor will not come up to speed, even though the rated voltage, rated frequency, and rated load are applied. The suspected trouble could be due to _____________. A. a faulty centrifugal switch B. broken rotor bars C. worn bearings D. all of the above

Description : A split-phase induction squirrel-cage motor will not come up to speed, even though the rated voltage, rated frequency, and rated load are applied. The suspected trouble could be due to _____________. A. a faulty centrifugal switch B. broken rotor bars C. worn bearings D. all of the above

Last Answer : Answer: D

A three-phase, squirrel cage, induction motor will run hot due to a/an ______________. A. improper brush position B. reversed commutating pole C. shorted stator D. high power factor

Description : A three-phase, squirrel cage, induction motor will run hot due to a/an ______________. A. improper brush position B. reversed commutating pole C. shorted stator D. high power factor

Last Answer : Answer: C

A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles

Description : A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles

Last Answer : Answer: A

In the illustrated device, the part labeled '1A' _________. EL-0001 A. are start and run windings for a single phase shaded pole induction motor B. is the stator for a polyphase induction motor C. is the armature for a squirrel cage rotor motor D. are direct current shunt field windings for a universal motor

Description : In the illustrated device, the part labeled '1A' _________. EL-0001 A. are start and run windings for a single phase shaded pole induction motor B. is the stator for a polyphase induction ... armature for a squirrel cage rotor motor D. are direct current shunt field windings for a universal motor

Last Answer : Answer: B

In the illustration, the assembly labeled 2 is a ________. EL-0001 A. wound rotor and shaft for a single phase induction motor B. conduction rotor and shaft for a polyphase induction motor C. squirrel cage rotor and shaft for a polyphase motor D. squirrel cage rotor for a single phase induction motor

Description : In the illustration, the assembly labeled 2 is a ________. EL-0001 A. wound rotor and shaft for a single phase induction motor B. conduction rotor and shaft for a polyphase induction motor C. ... cage rotor and shaft for a polyphase motor D. squirrel cage rotor for a single phase induction motor

Last Answer : Answer: C

The speed of a multi-speed, squirrel-cage, induction motor operating in a fixed frequency system can be changed by _____________. A. reconnecting stator windings for different numbers of poles B. changing the RPM of the rotor flux C. changing the phase sequence of the applied voltage D. reconnecting the stator so that no poles have the same polarity

Description : The speed of a multi-speed, squirrel-cage, induction motor operating in a fixed frequency system can be changed by _____________. A. reconnecting stator windings for different numbers of poles B. ... sequence of the applied voltage D. reconnecting the stator so that no poles have the same polarity

Last Answer : Answer: A

The speed of a squirrel-cage induction motor is determined by the ____________. A. diameter of the stator B. number of stator poles C. rotor winding resistance D. rotor conducting bars resistance

Description : The speed of a squirrel-cage induction motor is determined by the ____________. A. diameter of the stator B. number of stator poles C. rotor winding resistance D. rotor conducting bars resistance

Last Answer : Answer: B

In a three-phase, squirrel-cage type, induction motor the rotating magnetic field is established by the _____________. A. current induced in the rotor windings B. application of a three-phase voltage supply to the stator windings C. laminated steel core and aluminum conductors in the rotor D. interaction of the magnetic field caused by the induced current in the squirrel-cage bars with the magnetic field of the stator

Description : In a three-phase, squirrel-cage type, induction motor the rotating magnetic field is established by the _____________. A. current induced in the rotor windings B. application of a three-phase voltage ... caused by the induced current in the squirrel-cage bars with the magnetic field of the stator

Last Answer : Answer: B

Under normal conditions, the speed of a two-speed squirrel cage induction motor is changed by varying the ____________. A. frequency of the applied voltage B. resistance in the rotor circuit C. number of field poles D. amplitude of the applied voltage

Description : Under normal conditions, the speed of a two-speed squirrel cage induction motor is changed by varying the ____________. A. frequency of the applied voltage B. resistance in the rotor circuit C. number of field poles D. amplitude of the applied voltage

Last Answer : Answer: C

The speed of a three-phase squirrel-cage induction-type motor operating in a fixed frequency system is varied by changing the _____________. A. number of phases to the motor B. number of stator poles C. locked rotor current D. resistance of the rotor winding

Description : The speed of a three-phase squirrel-cage induction-type motor operating in a fixed frequency system is varied by changing the _____________. A. number of phases to the motor B. number of stator poles C. locked rotor current D. resistance of the rotor winding

Last Answer : Answer: B

The speed of a squirrel cage induction motor is determined by the _____________. A. diameter of the stator B. number of stator poles C. rotor winding resistance D. bar resistance of the conducting rotor

Description : The speed of a squirrel cage induction motor is determined by the _____________. A. diameter of the stator B. number of stator poles C. rotor winding resistance D. bar resistance of the conducting rotor

Last Answer : Answer: B

Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel cage motor does not? A. Slip rings B. End rings C. A centrifugal switch D. End plates

Description : Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel cage motor does not? A. Slip rings B. End rings C. A centrifugal switch D. End plates

Last Answer : Answer: A

A motor using a rheostat in the motor circuit to vary the speed is called a ____________. A. squirrel-cage induction motor B. regenerative braking motor C. wound-rotor induction motor D. synchronous motor

Description : A motor using a rheostat in the motor circuit to vary the speed is called a ____________. A. squirrel-cage induction motor B. regenerative braking motor C. wound-rotor induction motor D. synchronous motor

Last Answer : Answer: C

What is the working principle of double squirrel cage induction motor?

Description : What is the working principle of double squirrel cage induction motor?

Last Answer : In double squirrel cage motor outer cage rotor winding is of high resistance and low reactance. Inner cage winding is of high reactance and low resistance. At the time of starting rotor frequency is equal ... torque than outer cage at the time of running and the motor running torque is good enough.

A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Description : A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

Last Answer : Ans: B N = NS (1-S) and NS =120 f / p =120 x 50 /4 = 1500 rpm ∴N= 1500 (1-0.02) =1470 rpm

A motor which can conveniently be operated at lagging as well as leading power factors is the (A) squirrel cage induction motor. (B) wound rotor induction motor. (C) synchronous motor. (D) DC shunt motor.

Description : A motor which can conveniently be operated at lagging as well as leading power factors is the (A) squirrel cage induction motor. (B) wound rotor induction motor. (C) synchronous motor. (D) DC shunt motor.

Last Answer : (C) synchronous motor.

The power factor of a squirrel cage induction motor is (A) low at light load only. (B) low at heavy load only. (C) low at light and heavy load both. (D) low at rated load only.

Description : The power factor of a squirrel cage induction motor is (A) low at light load only. (B) low at heavy load only. (C) low at light and heavy load both. (D) low at rated load only.

Last Answer : (A) low at light load only.

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

Name the tests to be conducted for predetermining the performance of 3-phase induction machine.

Description : Name the tests to be conducted for predetermining the performance of 3-phase induction machine.

Last Answer : (a) No load test (b) Blocked rotor test