What are the differences between synchronous and induction motor?*

What are the differences between synchronous and induction motor?*
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1 Answer

Answer :

Synchronous motor : Constant speed on all loads, can be operated on a wide range of power  factors, not self starting, requires dc excitation.
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Related questions

What is a synchronous motor?

Description : What is a synchronous motor?

Last Answer : A constant-speed motor, the speed being dependent on the frequency of the ac supply and the number of poles for which it is designed.

How is the speed of a 3-phase induction motor varied?

Description : How is the speed of a 3-phase induction motor varied?

Last Answer : The speed of a normal 3-phase induction motor is a function of the frequency of the supply voltage. Changing the speed of such a motor hence requires building a 3-phase power frequency ... realised by using power MOSFETs (or IGBTs) capable of handling high voltages and fast switching speeds.

What is an induction motor?

Description : What is an induction motor?

Last Answer : An induction motor is an alternating current motor in which the primary winding on one member (usually the stator) is connected to the power source and a secondary winding or a squirrel-cage secondary winding on the other member (usually the rotor) carries the induced current

The application of mutual induction is: a. TV b. Radio c. Transformer d. Motor

Description : The application of mutual induction is: a. TV b. Radio c. Transformer d. Motor

Last Answer : c. Transformer

What is a synchronous condenser?

Description : What is a synchronous condenser?

Last Answer : A synchronous condenser is a device identical to a synchronous motor, whose shaft is not connected to anything but spins freely. Its purpose is not to convert electric power to mechanical power or vice ... or absorb reactive power as needed to adjust the grid's voltage, or to improve power factor.

The left hand rule correlates to (a) current, induced e.m.f. and direction of force on a conductor (b) magnetic field, electric field and direction of force on a conductor (c) self induction, mutual induction and direction of force on a conductor (d) current, magnetic field and direction of force on a conductor

Description : The left hand rule correlates to (a) current, induced e.m.f. and direction of force on a conductor (b) magnetic field, electric field and direction of force on a conductor (c) self induction, ... and direction of force on a conductor (d) current, magnetic field and direction of force on a conductor

Last Answer : (d) current, magnetic field and direction of force on a conductor

The principle of AC generator is: a. Mutual induction b. self induction c. electromagnetic induction d. Induction

Description : The principle of AC generator is: a. Mutual induction b. self induction c. electromagnetic induction d. Induction

Last Answer : b. self induction

The phenomenon of producing emf in the coil due to change of current in the coil itself is called: a. mutual induction b. self-induction c. self-inductance d. mutual inductance

Description : The phenomenon of producing emf in the coil due to change of current in the coil itself is called: a. mutual induction b. self-induction c. self-inductance d. mutual inductance

Last Answer : d. mutual inductance

A proton beam moves towards an observer. The direction of magnetic induction is a) towards right b) anticlockwise c) towards left d) clockwise

Description : A proton beam moves towards an observer. The direction of magnetic induction is a) towards right b) anticlockwise c) towards left d) clockwise

Last Answer : d) clockwise

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

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 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

The synchronous speed of an induction motor is the ________. A. speed at which the rotor turns B. speed of the rotating field C. frequency of the rotor current D. slip in per cent of rotor RPM

Description : The synchronous speed of an induction motor is the ________. A. speed at which the rotor turns B. speed of the rotating field C. frequency of the rotor current D. slip in per cent of rotor RPM

Last Answer : Answer: B

A shaded-pole motor is a ____________. A. synchronous motor B. three-phase induction motor C. compound-wound motor D. single-phase induction motor

Description : A shaded-pole motor is a ____________. A. synchronous motor B. three-phase induction motor C. compound-wound motor D. single-phase induction motor

Last Answer : Answer: D

The purpose of a cage rotor winding placed on the rotor of a synchronous motor is to _____________. A. provide excitation to the DC field B. start the machine as an induction motor C. contribute extra torque at synchronous speed D. prevent the machine from falling out of step

Description : The purpose of a cage rotor winding placed on the rotor of a synchronous motor is to _____________. A. provide excitation to the DC field B. start the machine as an induction motor C. contribute extra torque at synchronous speed D. prevent the machine from falling out of step

Last Answer : Answer: B

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

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

Why the induction motor never runs at synchronous speed?

Description : Why the induction motor never runs at synchronous speed?

Last Answer : If rotor & stator have same speed, no relative motion {Nr = Ns (1-s)}. Slip is zero, no voltage induce in rotor Current is zero, then torque is zero (T ∞ E2 I2 cos φ2). Thus induction motor never runs at synchronous speed.

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.

The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm

Description : The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm

Last Answer : (D) 1710 rpm

The drive motor used in a mixer-grinder is a (A) dc motor. (B) induction motor. (C) synchronous motor. (D) universal motor.

Description : The drive motor used in a mixer-grinder is a (A) dc motor. (B) induction motor. (C) synchronous motor. (D) universal motor.

Last Answer : Ans: D The universal motor is suitable for AC & DC both supply systems.

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 length cf air gap to be provided in ______ is primarily determined by power factor consideration. (a) d.c. series motor . (b) d.c. shunt motor (c) induction motor (d) synchronous motor

Description : The length cf air gap to be provided in ______ is primarily determined by power factor consideration. (a) d.c. series motor . (b) d.c. shunt motor (c) induction motor (d) synchronous motor

Last Answer : (c) induction motor

What will happen if the induction motor runs at synchronous speed ?

Description : What will happen if the induction motor runs at synchronous speed ?

Last Answer : Since there is always slip present in rotor it cannot run at synchronous speed no current will be developed hence no torque will developed

Synchronous wattage of induction motor means:

Description : Synchronous wattage of induction motor means: A) rotor input in watts B) stator input in watts C) combined stator and rotor input in watts D) shaft output in watts

Last Answer : Synchronous wattage of induction motor means: rotor input in watts 

A synchronous motor has better power factor as compared to that of an equivalent induction motor...

Description : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?

Last Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.

Which motor have more efficiency, synchronous motor or induction motor?

Description : Which motor have more efficiency, synchronous motor or induction motor?

Last Answer : Synchronous motor has more efficiency.

The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?

Description : The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?

Last Answer : Ns         equals        f/pair pole 50/4      - 12.5

CAT Scanners can detect density differences of the order of a) 50 percent b) 10 percent c) 1 percent d) 40 percent

Description : CAT Scanners can detect density differences of the order of a) 50 percent b) 10 percent c) 1 percent d) 40 percent

Last Answer : c) 1 percent

All electrical appliances are connected in parallel to each other between the main line and neutral wire to get a. same current b. same current and potential difference c. different current but same potential difference d. different current and potential differences

Description : All electrical appliances are connected in parallel to each other between the main line and neutral wire to get a. same current b. same current and potential difference c. different current but same potential difference d. different current and potential differences

Last Answer : c. different current but same potential difference

Stepper Motor What ?

Last Answer : Stepper Motor Such One Kind of Motor Which Equal In the corner Rotation Generated By To whom Step To say Is Since Step by step Step by step Equal In the corner Rotation Creation By So This one Stepper Motor Says.

Universal Motor What ?

Last Answer : that Motor AC And DC Both Supply A. Let's go Him Universal Motor Says.

Where is a rotor wound AC motor used?

Description : Where is a rotor wound AC motor used?

Last Answer : For starting heavy torques, mostly used on portable machines and small winches.

What can be possible reasons for a motor failing to start?

Description : What can be possible reasons for a motor failing to start?

Last Answer : No power , Fuse blown , Overload trip, contactor coil burnt , Contactors contacts bad, control circuit relay faulty, stop switch open circuit and start switch does not operate, hold on contact does not make and motor burnt

How can the direction of rotation of an AC motor be reversed?*

Description : How can the direction of rotation of an AC motor be reversed?*

Last Answer : By interchanging any two supply lines.

What are the basic parts of a DC motor?*

Description : What are the basic parts of a DC motor?*

Last Answer : Rotor and stator, field poles, commutator, brushes, fan impeller, bearing & housing, end covers and name plate.

Explain what happens if a DC motor is fed with AC supply

Description : Explain what happens if a DC motor is fed with AC supply

Last Answer : Motor will run at low speed, sparking at brushes, heat due to eddy current will finally burn the motor.

If a motor is wound star and you want to change to delta what should you do?

Description : If a motor is wound star and you want to change to delta what should you do?

Last Answer : Open the terminal connection box. Remove the shorting link connecting the common connection (star) point of A2, B2 and C2. With the 3 phase windings marked A1A2, B1B2, C1C2, connect A2 to B1, B2 to C1 and C2 to A1.

How is the speed of a DC motor varied?

Description : How is the speed of a DC motor varied?

Last Answer : To vary the speed of a DC motor we need a constant voltage power supply with a series POT resistor of higher watt rating. A Pulse Width Modulator (PWM) can be used.

Why are motor ratings given in KW and that of alternator and transformer given in KVA?

Description : Why are motor ratings given in KW and that of alternator and transformer given in KVA?

Last Answer : kW is the output mechanical power of a motor and is expressed in kW. kVA is the net (apparent) power input to the transformer. This input power is the output + losses. kW = kVA x system power factor

Which of the following converts electric energy into mechanical energy: a. Transformer b. DC generator c. Motor d. AC generator

Description : Which of the following converts electric energy into mechanical energy: a. Transformer b. DC generator c. Motor d. AC generator

Last Answer : d. AC generato

In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field

Description : In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field

Last Answer : d. gravitational field

The most common source of AC voltage is: a. motor b. generator c. cell d. transformer

Description : The most common source of AC voltage is: a. motor b. generator c. cell d. transformer

Last Answer : c. cell

When a motor is just started, back emf is almost ______: a. Infinite b. zero c. minimum d. maximum

Description : When a motor is just started, back emf is almost ______: a. Infinite b. zero c. minimum d. maximum

Last Answer : d. maximum

If the motor is overloaded, then the magnitude of ‘back emf’” a. Increases b. Decreases c. Constant d. Becomes zero

Description : If the motor is overloaded, then the magnitude of ‘back emf’” a. Increases b. Decreases c. Constant d. Becomes zero

Last Answer : Increases