A three phase slip ring induction motor with chopper controlled resistance has its torque

A three phase slip ring induction motor with chopper controlled resistance has its torque proportional to 

 (a) Rotor current (b) Stator resistance (c) Square of rotor current (d) Square root of rotor current 
by

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Answer :

A three phase slip ring induction motor with chopper controlled resistance has its torque proportional to Square of rotor current

by

Related questions

A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is:

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Last Answer : A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is: Slip frequency

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Description : A 400 V, 15 kW, 4-pole, 50 Hz, Y-connected induction motor has full load slip of 4%. The output torque of the machine at full load is  (A) 1.66 Nm (B) 95.50 Nm (C) 99.47 Nm (D) 624.73 Nm

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Description : The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the ... frequency of induced voltage across slip ring is A) 30 Hz B) 70 Hz C) 20 Hz D) 35 Hz

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A three-phase squirrel cage induction motor has a starting torque of 150% and a maximum torque of 300%

Description : A three-phase squirrel cage induction motor has a starting torque of 150% and a maximum torque of 300% with respect to rated torque at rated voltage and rated frequency. Neglect the stator resistance and rotational losses. The ... maximum torque is  (A) 13.48% (B) 16.42% (C) 18.92% (D) 26.79%

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A 3-phase induction motor is running at slip ‘s’. If its two supply leads are interchanged, then the operating

Description : A 3-phase induction motor is running at slip ‘s’. If its two supply leads are interchanged, then the operating slip at that instant will be:

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If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor

Description : If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is:

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A 3-phase induction motor is driving a constant torque load at rated voltage and frequency. If both voltage

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The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip increases, rotor reactance decreases. B. The pullout point on the torque curve is about seven times the normal full load torque value. C. At stand still, stator current is 150% of normal. D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Description : The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip ... D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Last Answer : Answer: D

To reverse the direction of rotation of a three-phase AC induction motor, do one of the following: w) reverse any two of the three-phase connections x) change the frequency of the applied AC power y) operate the motor below the stall torque at very high slip z) none of the above

Description : To reverse the direction of rotation of a three-phase AC induction motor, do one of the following: w) reverse any two of the three-phase connections x) change the frequency of the applied AC power y) operate the motor below the stall torque at very high slip z) none of the above

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At slip equal to infinity, the torque of a three phase induction motor is :-

Description : At slip equal to infinity, the torque of a three phase induction motor is :-  a) zero b) very small c) high d) very high

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The ratio of rotor output to rotor input in an induction motor is 0.96. The slip of the motor is

Description : The ratio of rotor output to rotor input in an induction motor is 0.96. The slip of the motor is (a) 0.04% (b) 4% (c) 6% (d) 12%

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The slip of an induction motor normally does not depend on

Description : The slip of an induction motor normally does not depend on  (A) rotor speed (B) synchronous speed (C) shaft torque (D) core-loss component

Last Answer : The slip of an induction motor normally does not depend on core-loss component

The frequency (fr) of the rotor current in an induction motor is given by the expression (s = slip,

Description : The frequency (fr) of the rotor current in an induction motor is given by the expression (s = slip, f = supply frequency)

Last Answer : The frequency (fr) of the rotor current in an induction motor is given by the expression fr = (s. f ) (s = slip, f = supply frequency)

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an

Description : In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is (A) 0.2 Ω (B) 0.3 Ω (C) 0.4 Ω (D) 0.5 Ω

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In a single phase induction motor driving a fan load, the reason for having a high resistance rotor is to achieve

Description : In a single phase induction motor driving a fan load, the reason for having a high resistance rotor is to achieve (A) low starting torque (B) quick acceleration (C) high efficiency (D) reduced size

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A degree of control over the speed of a slip ring induction motor can be obtained by _____________. A. adjusting governor linkage B. changing the number of phases to the motor C. inserting resistance into the stator circuit D. inserting resistance into the rotor circuit

Description : A degree of control over the speed of a slip ring induction motor can be obtained by _____________. A. adjusting governor linkage B. changing the number of phases to the motor C. inserting resistance into the stator circuit D. inserting resistance into the rotor circuit

Last Answer : Answer: D

The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted

Description : The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be

Last Answer : The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be 0.5 Ohm

An induction motor having full load torque of 60 Nm when delta connected develops a starting torque of

Description : An induction motor having full load torque of 60 Nm when delta connected develops a starting torque of 120 Nm. For the same supply voltage if the motor is changed to star connection, the starting torque developed will be  A) 40 Nm B) 60 Nm C) 90 Nm D) 120 Nm

Last Answer : An induction motor having full load torque of 60 Nm when delta connected develops a starting torque of 120 Nm. For the same supply voltage if the motor is changed to star connection, the starting torque developed will be 40 Nm

When the supply voltage to an induction motor is reduced by 10%, the maximum torque will decrease by

Description : When the supply voltage to an induction motor is reduced by 10%, the maximum torque will decrease by about  A) 5% B) 10% C) 20% D) 40%

Last Answer : When the supply voltage to an induction motor is reduced by 10%, the maximum torque will decrease by about 20%

The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the

Description : The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the ratio of supply voltage to supply frequency (V/f ) constant. At rated frequency of 50 Hz and rated voltage of 400 V ... load torque is constant  (A) 882 rpm (B) 864 rpm (C) 840 rpm (D) 828 rpm

Last Answer : The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the ratio of supply voltage to supply frequency (V/f ) constant. At rated frequency of 50 Hz and rated voltage of 400 ... torque is constant  (A) 882 rpm (B) 864 rpm (C) 840 rpm (D) 828 rpm

in a three-phase induction motor, the rotor field runs at the following speed with respect to the stator structure:

Description : in a three-phase induction motor, the rotor field runs at the following speed with respect to the stator structure: 

Last Answer : in a three-phase induction motor, the rotor field runs at the following speed with respect to the stator structure: At synchronous speed in the direction of stator field

A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the

Description : A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the starting current drawn is 6 times the full load current, and the full load slip is 4%, then ratio of the ... load torque is approximately equal to (A) 0.24 (B) 1.44 (C) 2.40 (D) 6.00

Last Answer : A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the starting current drawn is 6 times the full load current, and the full load slip is 4%, then ratio of the starting developed torque to the full load torque is approximately equal to 1.44

A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440

Description : A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440 rpm. The electrical frequency in Hz of the induced negative sequence current in the rotor is  (A) 100 (B) 98 (C) 52 (D) 48

Last Answer : A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440 rpm. The electrical frequency in Hz of the induced negative sequence current in the rotor is 98 

If an induction motor were to be operated at 90% rated voltage, _____________. A. there would be an increase in starting torque B. starting current would increase slightly C. synchronous speed would decrease slightly D. the slip would increase

Description : If an induction motor were to be operated at 90% rated voltage, _____________. A. there would be an increase in starting torque B. starting current would increase slightly C. synchronous speed would decrease slightly D. the slip would increase

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A single-phase induction motor having a relatively high starting torque, is the ___________. A. shaded pole motor B. wound-rotor motor C. capacitor-start motor D. resistance-start motor

Description : A single-phase induction motor having a relatively high starting torque, is the ___________. A. shaded pole motor B. wound-rotor motor C. capacitor-start motor D. resistance-start motor

Last Answer : Answer: C

Why is the starting torque of a resistance split-phase induction motor not high?

Description : Why is the starting torque of a resistance split-phase induction motor not high?

Last Answer : The starting torque is given as, Ts = K Im Is Sin Ф Where K = constant whose magnitude depends upon the design of the motor (i) The angle between Is and Im is small ... Im are not equal in magnitude, the rotating magnetic field is not uniform and the starting torque produced is small.

A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by...

Description : 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.

Draw power and control circuit for definite time-limit starter for slip-ring induction motor. Explain its working.

Description : Draw power and control circuit for definite time-limit starter for slip-ring induction motor. Explain its working.

Last Answer : Definite Time-limit Starter for Slip-ring Induction Motor: This starter is used for automatic control of acceleration of slip-ring induction motor at the time of starting. In this starter, the ... each phase, shorting the rotor winding terminals and final acceleration of the motor takes place. 

The stator mmf and rotor mmf of a 3-phase induction motor

Description : The stator mmf and rotor mmf of a 3-phase induction motor (A) are equal (B) rotate with slip speed (C) are opposite but rotate with synchronous speed (D) rotate with the same rotor speed 

Last Answer : a

A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting

Description : A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting torque of 600 NM. Its starting torque when star delta starter is used:

Last Answer : A 3-phase delta connected squirrel cage induction motor when started with a DOL starter has a starting torque of 600 NM. Its starting torque when star delta starter is used: 200 NM

In a 3-phase voltage source inverter used for speed control of induction motor, anti-parallel diodes are used

Description : In a 3-phase voltage source inverter used for speed control of induction motor, anti-parallel diodes are used across each switching device. The main purpose of diodes is to:

Last Answer : In a 3-phase voltage source inverter used for speed control of induction motor, anti-parallel diodes are used across each switching device. The main purpose of diodes is to: Allow the motor to return energy during regeneration

A single-phase induction motor with only the main winding excited would exhibit the following response at

Description : A single-phase induction motor with only the main winding excited would exhibit the following response at synchronous speed  (A) Rotor current is zero (B) Rotor current is non-zero and is ... and backward rotating fields are equal (D) Forward rotating field is more than the backward rotating field

Last Answer : A single-phase induction motor with only the main winding excited would exhibit the following response at synchronous speed  (A) Rotor current is zero (B) Rotor current is non-zero and is ... backward rotating fields are equal (D) Forward rotating field is more than the backward rotating field

No-load test on a 3-phase induction motor was conducted at different supply voltage and a plot of input

Description : No-load test on a 3-phase induction motor was conducted at different supply voltage and a plot of input power versus voltage was drawn. This curve was extrapolated to intersect the y-axis. The intersection point ... ) Core loss (B) Stator copper loss (C) Stray load loss (D) Friction and windage loss

Last Answer : No-load test on a 3-phase induction motor was conducted at different supply voltage and a plot of input power versus voltage was drawn. This curve was extrapolated to intersect the y-axis. The intersection point yields Friction and windage loss

The direction of rotation of a 3-phase induction motor is clockwise when it is supplied with 3-phase sinusoidal

Description : The direction of rotation of a 3-phase induction motor is clockwise when it is supplied with 3-phase sinusoidal voltage having phase sequence A-B-C. For counter clockwise rotation of the motor, the phase sequence of the power supply should be  (A) B-C-A (B) C-A-B (C) A-C-B (D) B-C-A or C-A-B

Last Answer : The direction of rotation of a 3-phase induction motor is clockwise when it is supplied with 3-phase sinusoidal voltage having phase sequence A-B-C. For counter clockwise rotation of the motor, the phase sequence of the power supply should be  A-C-B 

The type of single-phase induction motor having the highest power factor at full load is

Description : The type of single-phase induction motor having the highest power factor at full load is (A) shaded pole type (B) split-phase type (C) capacitor-start type (D) capacitor-run type

Last Answer : The type of single-phase induction motor having the highest power factor at full load is capacitor-run type

For a single phase capacitor start induction motor, which of the following statements is valid?

Description : For a single phase capacitor start induction motor, which of the following statements is valid?  A) The capacitor is used for power factor improvement B) The direction of rotation can be ... rotation cannot be changed D) The direction of rotation can be changed by interchanging the supply terminals

Last Answer : For a single phase capacitor start induction motor, which of the following statements is valid?  A) The capacitor is used for power factor improvement B) The direction of rotation can be ... cannot be changed D) The direction of rotation can be changed by interchanging the supply terminals

Consider the following statements: Star delta starter is used in 3-phase induction motor

Description : Consider the following statements: Star delta starter is used in 3-phase induction motor because it  1. Prevents heating of the motor winding  2. Ensures permissible minimum starting current  3. Is regulated by electricity ... and 4 are correct (c) 1, 3 and 4 are correct (d) 1 and 2 are correct 

Last Answer : Consider the following statements: Star delta starter is used in 3-phase induction motor because it  1. Prevents heating of the motor winding  2. Ensures permissible minimum starting current  3. Is regulated by ... and 4 are correct (c) 1, 3 and 4 are correct (d) 1 and 2 are correct 

The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?

Description : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?

Last Answer : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be 4.

Single phase induction motor usually operates on?

Last Answer : Single phase induction motor usually operates on 0.6 power factor lagging.

A single-phase induction motor is?

Last Answer : A single-phase induction motor is inherently non-self-starting with low torque.

The power factor of a single-phase induction motor is usually?

Last Answer : The power factor of a single-phase induction motor is usually lagging.

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

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

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 function of following parts of slip ring induction motor: (i) Slip ring (ii) Fan (iii) Brushes (iv) Frame

Description : State the function of following parts of slip ring induction motor: (i) Slip ring (ii) Fan (iii) Brushes (iv) Frame

Last Answer : Sr. No. Name of part Function 1 Slip ring 1) The rotor winding terminals are permanently connected to the slip rings. 2) Connects external resistance to rotor circuit through ... It provides mechanical support to the entire internal parts of motor. 2) Protects the inner parts.

Compare squirrel cage induction motor and slip ring induction motor any four points.

Description : Compare squirrel cage induction motor and slip ring induction motor any four points.

Last Answer : Comparison Between Squirrel Cage Induction Motor and Slip Ring Induction Motor: Sr. No. Squirrel Cage Induction Motor Slip Ring Induction Motor 1 Rotor is in the form of short circuited bars ... drive e.g. Lathe machine. Used where high starting torque is required e.g. Lifts.

Develop power and control diagram for secondary frequency acceleration starter of slip ring induction motor.

Description : Develop power and control diagram for secondary frequency acceleration starter of slip ring induction motor. 

Last Answer : Power and Control Circuit diagram for secondary frequency acceleration starter of slip ring induction motor:

A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Description : A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Last Answer : Answer: A