What are the methods of starting synchronous motor?

What are the methods of starting synchronous motor?
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1 Answer

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.
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Related questions

Why synchronous motor is not self starting?

Description : Why synchronous motor is not self starting?

Last Answer : Synchronous motor is a doubly excited machine i.e two electrical inputs are provided to it. It's stator winding which consists of a 3 phase winding is provided with 3 phase supply and rotor ... due to attractive or repulsive force and remain in standstill condition. Hence it is not self starting.

Hunting of a synchronous motor:

Description : Hunting of a synchronous motor:

Last Answer : When the mechanical load is constant, the rotor settles down to an absolutely constant speed with the torque angle fixed by the particular delivered power. When there is a change in load the rotor speed ... are short circuited; copper bars are embedded in the faces of the field poles of the motor.

What could be the reasons if a 3-phase synchronous motor fails to start?

Description : What could be the reasons if a 3-phase synchronous motor fails to start?

Last Answer : It is usually due to the following reasons a. Voltage may be too low. b. Too much starting load. c. Open circuit in one phase or short circuit. d. Field excitation may be excessive

A synchronous motor starts as usual but fails to develop its full torque. What could it be due to?

Description : A synchronous motor starts as usual but fails to develop its full torque. What could it be due to?

Last Answer : a. Exciter voltage may be too low. b. Field spool may be reversed c. There may be either open-circuit or short-circuit in the field.

In what way synchronous motor is different from other motors?

Description : In what way synchronous motor is different from other motors?

Last Answer : All dc and ac motors work on the same principle. Synchronous motor operates due to magnetic locking taking place between stator and rotor magnetic fields.

State the characteristic features of synchronous motor.

Description : State the characteristic features of synchronous motor.

Last Answer : a. the motor is not inherently self starting b. The speed of operation is always in synchronous with the supply frequency irrespective of load conditions c. The motor is capable of operating at any power factor.

Write the applications of synchronous motor.

Description : Write the applications of synchronous motor.

Last Answer : a. Used for power factor improvement in sub-stations and in industries. b. As synchronous condenser c. Used for constant speed applications

What are V and inverted V curves of synchronous motor ?

Description : What are V and inverted V curves of synchronous motor ?

Last Answer : The variation of magnitude of line current with respect to the field current is called V curve . The variation of power factor with respect to the field current is called inverted V curve.

How the synchronous motor can be used as s synchronous condenser?

Description : How the synchronous motor can be used as s synchronous condenser?

Last Answer : Synchronous motor is operated on over excitation so as to draw leading reactive current and power from the supply lines. This compensates the lagging current and power requirement of the load making ... to become unity. The motor does the job of capacitors and hence called as synchronous condenser.

Why a synchronous motor is a constant speed motor?

Description : Why a synchronous motor is a constant speed motor?

Last Answer : When load increase in synchronous motor the load angle δ also increases but speed remains constant. The further increase in load cause further increase in load angle. When load angle reaches ... out of synchronism. Hence the motor rotates at synchronous speed otherwise it comes out of synchronism.

What is the effect on speed if the load is increased on a 3 phase synchronous motor?

Description : What is the effect on speed if the load is increased on a 3 phase synchronous motor?

Last Answer : The speed of operation remains constant from no load to maximum load in the motor operating at constant frequency bus bars.

Why damper windings are used in synchronous motor? Or How synchronous motor is started as squirrel cage motor?

Description : Why damper windings are used in synchronous motor? Or How synchronous motor is started as squirrel cage motor?

Last Answer : The damper winding consists of short circuited copper bars embedded in the the face of the rotor poles. When an ac supply is provided to stator of a 3-phase synchronous motor, stator winding produces ... magnetic field and damper winding is zero. Hence there will be no emf induced in damper winding.

What is pony motor starting?

Description : What is pony motor starting?

Last Answer : In this method the rotor is made to rotate by some external device called pony motors. Once the rotor attains synchronous speed, the DC excitation to the rotor is switched on. Once synchronism is established the pony motor is decoupled. The synchronous motor continuously runs at synchronous speed.

Distinguish between synchronous phase modifier and synchronous condenser

Description : Distinguish between synchronous phase modifier and synchronous condenser

Last Answer : A synchronous motor used to change the power factor or power factor in the supply lines is called synchronous phase modifier. A synchronous motor operated at no load with over excitation condition to draw large leading reactive current and power is called a synchronous condenser.

What is synchronous condenser?

Description : What is synchronous condenser?

Last Answer : An over-excited synchronous motor under no load , used for the improvement of power factor is called as synchronous condenser because, like a capacitor it takes a leading current.

What is critical excitation?

Description : What is critical excitation?

Last Answer : The excitation for which power factor of the synchronous motor is unity and the back emf is equal to supply voltage.

What is over excitation?

Description : What is over excitation?

Last Answer : The excitation for which power factor of the synchronous motor is leading and the back emf is greater than supply voltage.

What is under excitation?

Description : What is under excitation?

Last Answer : The excitation for which power factor of the synchronous motor is lagging and the back emf is less than supply voltage.

What is normal excitation?

Description : What is normal excitation?

Last Answer : The excitation for which power factor of the synchronous motor is lagging and the back emf is equal to supply voltage.

What is pull out torque?

Description : What is pull out torque?

Last Answer : The maximum torque developed by the motor without pulling out of synchronism is called pull out torque. Its value varies from 1.5 to 3.5 times full load torque.

What is pull in torque?

Description : What is pull in torque?

Last Answer : The torque which is required to pull the motor into synchronism when it is running as induction motor is called pull in torque.

What are the effects of hunting?

Description : What are the effects of hunting?

Last Answer : Loses synchronism Develops mechanical stress on rotor shaft Increase machine losses Increase temperature of machine

What is hunting?

Description : What is hunting?

Last Answer : The sudden changes of load on synchronous motor set up oscillations in the rotor. Such oscillation of rotor about its new equilibrium position is called hunting.

What is the function of damper winding?

Description : What is the function of damper winding?

Last Answer : To provide starting torque To prevent or minimize hunting

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.

List different starting methods of three phase synchronous motor. Explain any one of them.

Description : List different starting methods of three phase synchronous motor. Explain any one of them.

Last Answer : Different Starting Methods of Three Phase Synchronous Motor: As synchronous motor is not self starting, different methods of starting are as follows: 1) By using an Induction (Pony) motor 2) ... . The rotor gets pulled into synchronism and starts running at constant speed as a synchronous motor. 

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

Last Answer : Answer: D

The purpose of squirrel-cage windings in a synchronous motor is to ______________. A. provide more precise balancing B. produce a higher power factor C. eliminate arcing between the stator and the frame D. provide a means for starting

Description : The purpose of squirrel-cage windings in a synchronous motor is to ______________. A. provide more precise balancing B. produce a higher power factor C. eliminate arcing between the stator and the frame D. provide a means for starting

Last Answer : Answer: D

The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Description : The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Last Answer : Answer: C

A damper winding is designed as part of a synchronous motor to ____________. A. increase efficiency B. provide starting torque C. provide excitation D. eliminate slippage

Description : A damper winding is designed as part of a synchronous motor to ____________. A. increase efficiency B. provide starting torque C. provide excitation D. eliminate slippage

Last Answer : Answer: B

The function of amortisseur, or damper windings in a synchronous motor is to _____________. A. eliminate slippage B. provide excitation C. provide starting torque D. increase efficiency

Description : The function of amortisseur, or damper windings in a synchronous motor is to _____________. A. eliminate slippage B. provide excitation C. provide starting torque D. increase efficiency

Last Answer : Answer: C

The function of damper windings in a synchronous motor is to _____________. A. eliminate slippage B. provide excitation C. provide starting torque D. increase efficiency

Description : The function of damper windings in a synchronous motor is to _____________. A. eliminate slippage B. provide excitation C. provide starting torque D. increase efficiency

Last Answer : Answer: C

Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Description : Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Last Answer : Answer: C

While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates the _____________. A. motor has started properly B. field windings are grounded C. slip rings are dirty D. power transmission cables are grounded

Description : While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates the _____________. A. motor has started ... field windings are grounded C. slip rings are dirty D. power transmission cables are grounded

Last Answer : Answer: A

Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. The starting current is held below the rated current. D. The field winding is energized for starting purposes only.

Description : Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. ... is held below the rated current. D. The field winding is energized for starting purposes only.

Last Answer : Answer: A

Which motor has high Starting Torque and Staring current DC motor, Induction motor or Synchronous motor?

Description : Which motor has high Starting Torque and Staring current DC motor, Induction motor or Synchronous motor?

Last Answer : DC Series motor has high starting torque. We can not start the Induction motor and Synchronous motors on load, but can not start the DC series motor without load.

Which Motor Has High Starting Torque And Staring Current Dc Motor, Induction Motor Or Synchronous Motor?

Description : Which Motor Has High Starting Torque And Staring Current Dc Motor, Induction Motor Or Synchronous Motor?

Last Answer : DC Series motor has high starting torque. We can not start the Induction motor and Synchronous motors on load, but can not start the DC series motor without load.

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.

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

A synchronous motor can be made self starting by providing?

Description : A synchronous motor can be made self starting by providing?

Last Answer : A synchronous motor can be made self-starting by providing damper bar.

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

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

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

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 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

If a synchronous motor begins to vibrate severely and pull out of synchronism, the cause may be ____________. A. an overload B. an open in the field coils C. no exciter voltage D. all of the above

Description : If a synchronous motor begins to vibrate severely and pull out of synchronism, the cause may be ____________. A. an overload B. an open in the field coils C. no exciter voltage D. all of the above

Last Answer : Answer: D

The speed of a synchronous motor is varied by _____________. A. interchanging any two of the three live leads B. changing the voltage of the system C. changing the input frequency D. increasing the field excitation

Description : The speed of a synchronous motor is varied by _____________. A. interchanging any two of the three live leads B. changing the voltage of the system C. changing the input frequency D. increasing the field excitation

Last Answer : Answer: C

What type of electric motor is commonly used to start small auxiliary diesel engines? A. synchronous B. series C. shunt D. cage

Description : What type of electric motor is commonly used to start small auxiliary diesel engines? A. synchronous B. series C. shunt D. cage

Last Answer : Answer: B

Which of the instruments listed could be use to locate a grounded field coil in a synchronous motor? A. Ammeter B. Voltmeter C. Megohmmeter D. Frequency meter

Description : Which of the instruments listed could be use to locate a grounded field coil in a synchronous motor? A. Ammeter B. Voltmeter C. Megohmmeter D. Frequency meter

Last Answer : Answer: C