What are the methods to control the speed of singlephase motor?

What are the methods to control the speed of singlephase motor?
by

1 Answer

Answer :

In AC single-phase motors speed control can not be
achieve as smooth as in DC motor. There are following
few methods of speed control.
a. By changing the number of poles of stator.
b. By changing the applied voltage to the stator.
c. Frequency control method.
d. Rotor rheostat control.
e. By operating two motors in concatenation or cascade
or tandem method.
f. By injecting an emf in the rotor circuit.
g. By changing slip.
by

Related questions

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

What are the speed control methods of induction motor?

Description : What are the speed control methods of induction motor?

Last Answer : a. By controlling the supply voltage. b. By controlling the supply frequency (Ns = 120f / P). c. By varying the number of poles (Ns = 120f / P). d. By rotor rheostatic control (for small speed variation).

Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Description : Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Last Answer : 1) Pole Changing Method:  Synchronous speed is given by, From the above equation of synchronous speed, it can be seen that synchronous speed (and hence, running speed) can ... in voltage and consequently the speed decreases and vice versa. Ultimately speed depends on the supply voltage.

With the help of neat diagrams,explain the following methods of speed control in DC series motor. i) Field diverter method. ii) Armature diverter method.

Description : With the help of neat diagrams,explain the following methods of speed control in DC series motor. i) Field diverter method. ii) Armature diverter method.

Last Answer : (i) Field diverter method: - Resistance connected in parallel with field winding -By adjusting this resistance current can by diverted from field winding -Thus field current decreases and the speed can be ... decreased, the flux must increase and hence speed is decreased than the rated speed.

What are the speed control methods of dc motor?

Description : What are the speed control methods of dc motor?

Last Answer : Field control of DC motor Armature control of DC motor

speed control methods of three phase induction motor?

Description : speed control methods of three phase induction motor?

Last Answer : Speed control of three phase induction motor

Methods to control speed of Wound Rotor Motors?

Description : Methods to control speed of Wound Rotor Motors?

Last Answer : The speed of wound rotor motors are changed by changing the slip of the motor. This can be achieved by: Varying the stator line voltage Varying the resistance in the rotor circuit Inserting and varying a foreign voltage source in the rotor circuit

The advantage(s) of the method of D.C. motor speed control shown in the illustration is/are ______________. EL-0101 A. elimination of armature starting resistor losses B. elimination of speed instability with variable loads C. the ease of reversing motor direction D. all of the above

Description : The advantage(s) of the method of D.C. motor speed control shown in the illustration is/are ______________. EL-0101 A. elimination of armature starting resistor losses B. elimination of speed instability with variable loads C. the ease of reversing motor direction D. all of the above

Last Answer : Answer: D

The method of D.C. motor speed control shown in the illustration is known as _____________. EL-0101 A. Ward-Leonard B. Sperry-Rand C. Atlas-Copco D. Burmeister-Wain

Description : The method of D.C. motor speed control shown in the illustration is known as _____________. EL-0101 A. Ward-Leonard B. Sperry-Rand C. Atlas-Copco D. Burmeister-Wain

Last Answer : Answer: A

The basic type of D.C. motor speed control where a generator armature directly feeds the motor armature and the motor and generator fields are excited by a separate D.C. source is called ___________________. A. Burmeister-Wain B. Ward-Leonard C. Sperry-Rand D. Atlas-Copco

Description : The basic type of D.C. motor speed control where a generator armature directly feeds the motor armature and the motor and generator fields are excited by a separate D.C. source is called ___________________. A. Burmeister-Wain B. Ward-Leonard C. Sperry-Rand D. Atlas-Copco

Last Answer : Answer: B

The speed of a wound-rotor induction motor _____________. A. will be fixed by the number of field poles B. can be varied by a rheostat-type control C. can only be synchronous speed at full load D. can only attain synchronous speed at no load

Description : The speed of a wound-rotor induction motor _____________. A. will be fixed by the number of field poles B. can be varied by a rheostat-type control C. can only be synchronous speed at full load D. can only attain synchronous speed at no load

Last Answer : Answer: B

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 variable resistance placed in the rotor circuit of a wound-rotor induction motor provides for __________. A. speed control B. frequency control C. voltage control D. use as a split-phase motor

Description : The variable resistance placed in the rotor circuit of a wound-rotor induction motor provides for __________. A. speed control B. frequency control C. voltage control D. use as a split-phase motor

Last Answer : Answer: A

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.

Give two basic speed control scheme of DC shunt motor?

Description : Give two basic speed control scheme of DC shunt motor?

Last Answer : Answer: 1. By using flux control method: in this method a rheostat is connected across the field wdg to control the field current. So by changing the current the flux produced by the field wdg can ... ) can be varied, and since speed is directly proportional to Eb-IaRa the speed can be controlled.

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

How speed control of DC motor can be achieved?

Description : How speed control of DC motor can be achieved?

Last Answer : Induced emf in the armature E = P * φ * Z * N / A * 60 volts. Where Z and A are constant. N ∝ Eb / φ N ∝ V - Ia ra / φ. We can consider that the Ia ra drop is ... be varied by varying either applied voltage to the armature and by varying field flux or field strength per pole or total field flux.

Which of the following methods should be used to test for an 'open' coil in an AC motor stator? A. Test with an ohmmeter, one test lead on the shaft, and the other test lead to the stator leads. B. Test with an ohmmeter with the test leads between the stator leads. C. Use a growler, listening for noise and vibration to diminish when over an open coil. D. Use a growler, listening for noise and vibration to increase when over an open coil.

Description : Which of the following methods should be used to test for an 'open' coil in an AC motor stator? A. Test with an ohmmeter, one test lead on the shaft, and the other test lead to the stator leads ... an open coil. D. Use a growler, listening for noise and vibration to increase when over an open coil.

Last Answer : Answer: B

What are methods available for making single phase induction motor a self starting?

Description : What are methods available for making single phase induction motor a self starting?

Last Answer : By slitting the single phase, by providing shading coil in the poles.

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 methods of starting synchronous motor?

Description : What are the methods of starting synchronous motor?

Last Answer : 1. Pony motor starting( using ac or dc motor) 2. Starting as squirrel cage Induction motor or using damper winding 3. Starting as slip ring Induction motor or synchronous motor 4. Using dc machine coupled to it.

What are the methods to self-starting of single-phase motor?

Description : What are the methods to self-starting of single-phase motor?

Last Answer : a. Splitting one phase into two phases. b. By using capacitor. c. By using repulsion method. d. By shading the poles. e. By connecting the field in series with the rotor having winding with commutator (AC series motor or universal motor).

Mention the methods for starting an induction motor?

Description : Mention the methods for starting an induction motor?

Last Answer :  The different methods of starting an induction motor  DOL:direct online starter  Star delta starter  Auto transformer starter  Resistance starter  Series reactor starter

What are the different methods for the starting of a synchronous motor.

Description : What are the different methods for the starting of a synchronous motor.

Last Answer : Starting methods: Synchronous motor can be started by the following two methods: By means of an auxiliary motor: The rotor of a synchronous motor is rotated by auxiliary motor. Then ... rotor and the rotor starts rotating continuously as the rotor field is locked with stator revolving field.

What are the two methods of control in ac voltage controllers?

Description : What are the two methods of control in ac voltage controllers?

Last Answer : a. ON-OFF control b. Phase control

Suggest the different methods to control the speed of rotation of steam turbine constant at all varying loads.

Description : Suggest the different methods to control the speed of rotation of steam turbine constant at all varying loads.

Last Answer : Following are the different methods to control the speed of rotation of steam turbine constant at all varying loads;  a) Throttle governing b) Nozzle control governing c) By pass governing d) Combine throttle and nozzle control governing e) Combine throttle and by pass governing

A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Description : A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.

Last Answer : The number of poles in an induction motor can be calculated using the following formula: No. of poles = (120 * frequency) / speed In this case, the number of poles would be calculated as follows: No. of poles = ( ... ) - 50 Hz = 8.08 Hz So the motor has 6 poles and a slip frequency of 8.08 Hz.

Which of the following statements is true concerning the motor controller diagram shown in the illustration? EL-0023 A. Terminal 'T2' is hot only on high speed. B. Both indicating lights will be lit on both high and low speeds as they are connected to the common lead when the motor is running. C. Overload protection is provided for high speed operation only. D. 'L2' is always connected to 'T2' whenever the motor is running.

Description : Which of the following statements is true concerning the motor controller diagram shown in the illustration? EL-0023 A. Terminal 'T2' is hot only on high speed. B. Both indicating lights will be lit on ... high speed operation only. D. 'L2' is always connected to 'T2' whenever the motor is running.

Last Answer : Answer: D

A four pole turbogenerator is used in conjunction with a 160 pole propulsion motor. If the generator is turning at 3,200 RPM, what is the current speed of the propeller? A. 40 RPM B. 60 RPM C. 80 RPM D. 100 RPM

Description : A four pole turbogenerator is used in conjunction with a 160 pole propulsion motor. If the generator is turning at 3,200 RPM, what is the current speed of the propeller? A. 40 RPM B. 60 RPM C. 80 RPM D. 100 RPM

Last Answer : Answer: C

Which statement is true concerning a split-phase induction motor? A. Motor rotation can be reversed without changing the windings or leads. B. Motor speed can be readily adjusted from zero to full speed. C. The motor will run as a generator with the proper wiring. D. Motor rotation can be reversed by reversing the leads on the starting winding.

Description : Which statement is true concerning a split-phase induction motor? A. Motor rotation can be reversed without changing the windings or leads. B. Motor speed can be readily adjusted from zero to full ... proper wiring. D. Motor rotation can be reversed by reversing the leads on the starting winding.

Last Answer : Answer: D

The most practical method of controlling the RPM of a step-speed AC motor is to _____________. A. change input voltage B. vary the number of poles C. vary power factor D. change the number of brushes

Description : The most practical method of controlling the RPM of a step-speed AC motor is to _____________. A. change input voltage B. vary the number of poles C. vary power factor D. change the number of brushes

Last Answer : Answer: 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 four-pole 60-hertz induction motor has a synchronous speed of 1800 RPM and a slip of 4 percent at full load. What will be its full load speed? A. 1728.0 RPM B. 1730.7 RPM C. 1800.0 RPM D. 1872.0 RPM

Description : A four-pole 60-hertz induction motor has a synchronous speed of 1800 RPM and a slip of 4 percent at full load. What will be its full load speed? A. 1728.0 RPM B. 1730.7 RPM C. 1800.0 RPM D. 1872.0 RPM

Last Answer : Answer: A

A single-phase induction motor starts, comes up to about 75% rated speed, slows down to a lower speed, and accelerates again. The problem is most likely in the ____________. A. starting winding B. running winding C. starting capacitor D. running centrifugal switch

Description : A single-phase induction motor starts, comes up to about 75% rated speed, slows down to a lower speed, and accelerates again. The problem is most likely in the ____________. A. starting winding B. running winding C. starting capacitor D. running centrifugal switch

Last Answer : Answer: B

A four-pole, 60 cycle, squirrel-cage motor has a full load speed of 1725 RPM. What will be the percent of slip at full load? A. 4.16 B. 4.34 C. 95.66 D. 95.84

Description : A four-pole, 60 cycle, squirrel-cage motor has a full load speed of 1725 RPM. What will be the percent of slip at full load? A. 4.16 B. 4.34 C. 95.66 D. 95.84

Last Answer : Answer: A

If the synchronous speed of a 12 pole, polyphase, induction motor operating at 60 Hz were 600 RPM, how many poles will be required in a similar motor operating at the same frequency but having a synchronous speed of 900 RPM? A. 4 B. 6 C. 8 D. 18

Description : If the synchronous speed of a 12 pole, polyphase, induction motor operating at 60 Hz were 600 RPM, how many poles will be required in a similar motor operating at the same frequency but having a synchronous speed of 900 RPM? A. 4 B. 6 C. 8 D. 18

Last Answer : Answer: C

The prime mover of an AC two pole main propulsion generator drives the generator at 3600 RPM. If the main propulsion motor has 80 poles, what will be the propeller speed? A. 45 RPM B. 80 RPM C. 90 RPM D. 180 RPM

Description : The prime mover of an AC two pole main propulsion generator drives the generator at 3600 RPM. If the main propulsion motor has 80 poles, what will be the propeller speed? A. 45 RPM B. 80 RPM C. 90 RPM D. 180 RPM

Last Answer : Answer: C

What is the rotor speed of a four pole, 60 cycle, induction motor operating at full load with 3% slip? A. 270 RPM B. 540 RPM C. 873 RPM D. 1746 RPM

Description : What is the rotor speed of a four pole, 60 cycle, induction motor operating at full load with 3% slip? A. 270 RPM B. 540 RPM C. 873 RPM D. 1746 RPM

Last Answer : Answer: D

A single-phase induction motor will only start if you spin the rotor rapidly with the line switch closed. After starting, its speed fluctuates between very slow and half-speed. The problem probably lies in the ________. A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding

Description : A single-phase induction motor will only start if you spin the rotor rapidly with the line switch closed. After starting, its speed fluctuates between very slow and half-speed. The problem ... in the ________. A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding

Last Answer : Answer: D

Which of the conditions listed will indicate the need to clean the insulation on the windings of an electric motor? A. Higher than normal operating temperature. B. Excessive vibration at normal speed. C. Sparking at the brushes. D. High megger readings.

Description : Which of the conditions listed will indicate the need to clean the insulation on the windings of an electric motor? A. Higher than normal operating temperature. B. Excessive vibration at normal speed. C. Sparking at the brushes. D. High megger readings.

Last Answer : Answer: A

If a three-phase induction motor is operated under a light load and it develops an open in one of its supply lines, the motor will _____________. A. continue to run, but will vibrate and have reduced torque B. speed up due to the reduced number of poles C. run cooler due to reduced current flow D. stop

Description : If a three-phase induction motor is operated under a light load and it develops an open in one of its supply lines, the motor will _____________. A. continue to run, but will vibrate and have reduced ... speed up due to the reduced number of poles C. run cooler due to reduced current flow D. stop

Last Answer : Answer: A

The effect of carrying field excitation excessively high on a synchronous motor will result in a _____________. A. tendency for the motor to fall out of step B. tendency for the motor to overspeed C. tendency for the motor to overheat D. loss of motor speed regulation

Description : The effect of carrying field excitation excessively high on a synchronous motor will result in a _____________. A. tendency for the motor to fall out of step B. tendency for the motor to overspeed C. tendency for the motor to overheat D. loss of motor speed regulation

Last Answer : Answer: C

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

If the centrifugal switch or relay used for cutting out the starting winding of a split-phase induction motor fails to open once the motor is in operation, the _____________. A. motor will overspeed B. starting winding will burn out C. motor will immediately stall under load D. motor torque will be above normal at rated speed

Description : If the centrifugal switch or relay used for cutting out the starting winding of a split-phase induction motor fails to open once the motor is in operation, the _____________. A. motor will overspeed B ... C. motor will immediately stall under load D. motor torque will be above normal at rated speed

Last Answer : Answer: B

A single-phase induction motor fails to start. The rotor is spun rapidly with the line switch closed. Having started by this method it is noted that the motor fluctuates between a very slow speed and half speed. The problem probably lies in the ______ A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding

Description : A single-phase induction motor fails to start. The rotor is spun rapidly with the line switch closed. Having started by this method it is noted that the motor fluctuates between a very slow ... lies in the ______ A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding

Last Answer : Answer: D

Which of the following problems will most likely occur if the starting winding of a split-phase induction motor failed to cutout once the motor was in continuous operation? A. The motor will overspeed. B. The motor will run at a reduced speed. C. A time delay will stop the motor. D. The winding will burn out.

Description : Which of the following problems will most likely occur if the starting winding of a split-phase induction motor failed to cutout once the motor was in continuous operation? A. The motor will overspeed. B. The ... reduced speed. C. A time delay will stop the motor. D. The winding will burn out.

Last Answer : Answer: D