Description : How is a three phase cage induction motor self starting?
Answer :
Any type of induction motor is self starting. Because the reason for torqe production require two flux displaced by some angle theta.If theta is constant with time then torqe will be constant;if ... torqe also pulsating. In induction motor this angle theta is not pulsating.so it is self starting
asked
Mar 17, 2018
by
anonymous
Description : Is induction motor is self starting?
Answer :
Single phase induction motor is not self starting. Three phase induction motor is self starting.
asked
Mar 17, 2018
by
anonymous
Description : List different starting methods of three phase synchronous motor. Explain any one of them.
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.
asked
May 7, 2020
by
anonymous
Answer :
The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.
asked
Mar 20, 2018
by
anonymous
Answer :
In a capacitor start motor, the phase displacement between starting and running winding can be nearly 90°.
asked
Mar 20, 2018
by
anonymous
Answer :
A synchronous motor can develop synchronous torque at synchronous speed.
asked
Mar 20, 2018
by
anonymous
Description : How can we reverse the direction of rotation of synchronous motor?
Answer :
By reversing supply phase sequence we can reverse the direction of rotation of synchronous motor.
asked
Mar 18, 2018
by
anonymous
Description : Can we use the synchronous motor as the synchronous capacitor?
Answer :
Yes, we can use the synchronous motor as the synchronous capacitor when the synchrnous motor is overexcited.
asked
Mar 18, 2018
by
anonymous
Description : Hunting in synchronous motor cannot be due to?
Answer :
Hunting in synchronous motor cannot be due to windage friction.
asked
Mar 18, 2018
by
anonymous
Description : If the field of synchronous motor is under excited, power factor will be?
Answer :
If the field of synchronous motor is under excited, power factor will be lagging.
asked
Mar 18, 2018
by
anonymous
Answer :
A synchronous motor running with normal excitation adjusts to load increases essentially by increase in armature current.
asked
Mar 20, 2018
by
anonymous
Answer :
The value of starting capacitor of a fractional horse power motor will be 300 uF .
asked
Mar 20, 2018
by
anonymous
Answer :
Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a magnetic relay.
asked
Mar 20, 2018
by
anonymous
Answer :
The rotor developed by a single-phase motor at starting is zero.
asked
Mar 20, 2018
by
anonymous
Answer :
Slip-rings in a synchronous motor carry direct current.
asked
Mar 20, 2018
by
anonymous
Answer :
The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.
asked
Mar 20, 2018
by
anonymous
Description : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
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.
asked
Mar 20, 2018
by
anonymous
Answer :
In case one phase of a three-phase synchronous motor is short-circuited the motor will not start.
asked
Mar 20, 2018
by
anonymous
Answer :
In a synchronous motor, the armature current has large values for high and low excitation.
Answer :
The size of a synchronous motor decreases with the increase in flux density.
Answer :
The duration of sudden short-circuit test on a synchronous motor is usually about one second.
asked
Mar 20, 2018
by
anonymous
Description : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?
Answer :
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.
asked
Mar 20, 2018
by
anonymous
Answer :
The construction of a synchronous motor resembles an alternator.
asked
Mar 20, 2018
by
anonymous
Description : The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?
asked
Mar 20, 2018
by
anonymous
Description : In a synchronous motor which losses varies with load?
Answer :
In a synchronous motor, copper losses varies with load.
asked
Mar 18, 2018
by
anonymous
Answer :
Synchronous motors are generally not self-starting because the direction of instantaneous torque reverses after half cycle.
asked
Mar 20, 2018
by
anonymous
Answer :
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.
asked
Mar 20, 2018
by
anonymous
Answer :
The coupling angle or load angle of synchronous motor is defined as the angle between the rotor and the stator poles of opposite polarity.
asked
Mar 20, 2018
by
anonymous
Answer :
If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then the stator current will be zero.
asked
Mar 20, 2018
by
anonymous
Answer :
The armature current of the synchronous motor has large values for low and high excitation.
asked
Mar 20, 2018
by
anonymous
Description : Which motor have more efficiency, synchronous motor or induction motor?
Answer :
Synchronous motor has more efficiency.
asked
Mar 18, 2018
by
anonymous
Description : If we change the excitation of synchronous machine will it affect on motor speed?
Answer :
No, If we change the excitation of synchronous machine it will not affect on motor speed.
asked
Mar 18, 2018
by
anonymous
Description : What is the maximum value of torque angle in synchronous motor?
Answer :
The maximum value of torque angle in synchronous motor is 90 degrees electrical.
asked
Mar 18, 2018
by
anonymous
Description : If the load of the normally excited synchronous motor is increased the power factor will?
Answer :
If the load of the normally excited synchronous motor is increased the power factor will become lagging.
asked
Mar 18, 2018
by
anonymous
Description : The synchronous motor which works on leading power factor and does not drive any mechanical load is called?
Answer :
The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.
asked
Mar 18, 2018
by
anonymous
Description : The damping winding in synchronous motor is generally used to?
Answer :
The damping winding in synchronous motor is generally used to provide starting torque and prevent hunting.
asked
Mar 18, 2018
by
anonymous
Description : An unexcited single phase synchronous motor is ?
Answer :
An unexcited single-phase synchronous motor is reluctance motor.
asked
Mar 18, 2018
by
anonymous
Description : The back emf of synchronous motor depends on?
Answer :
The back emf of synchronous motor depends on load angle.
asked
Mar 18, 2018
by
anonymous
Description : Synchronous motor always runs at which speed?
Answer :
Synchronous motor always runs at synchronous speed.
asked
Mar 18, 2018
by
anonymous
Description : The synchronous motor will develop maximum power when the load angle is?
Answer :
The synchronous motor will develop maximum power when the load angle is 900.
asked
Mar 18, 2018
by
anonymous
Description : what will happen when excitation of an unloaded salient pole synchronous motor suddenly gets disconnected?
Answer :
When excitation of an unloaded salient pole synchronous motor suddenly gets disconnected the motor will stop.
asked
Mar 18, 2018
by
anonymous
Description : Three phase synchronous motor will have how many sliprings?
Answer :
Three phase synchronous motor will have two sliprings.
asked
Mar 18, 2018
by
anonymous
Answer :
The rotor of a hysteresis motor is made of chrome steel.
asked
Mar 20, 2018
by
anonymous
Description : In a self-controlled synchronous motor fed from a variable frequency inverter (1) the rotor poles invariably have damper windings (2) there are stability problems (3) the speed of the rotor decides stator frequency (4) the frequency of the stator decides the rotor speed
Answer :
In a self-controlled synchronous motor fed from a variable frequency inverter the frequency of the stator decides the rotor speed
asked
Apr 29, 2018
by
anonymous
Answer :
Series motor has got maximum self relieving property.
asked
Mar 20, 2018
by
anonymous
Answer :
Yes, we can make the power factor of synchronous motor leading by adjusting its excitation.
asked
Mar 6, 2018
by
anonymous
Description : In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high resistance winding. (C) Small current flows through the outer high resistance winding. (D) Large current flows through the inner low resistance winding.
Answer :
In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.
asked
May 8, 2018
by
anonymous
Answer :
The starting resistance of a D.C. motor is generally low.
asked
Mar 20, 2018
by
anonymous
Answer :
For starting a D.C. motor a starter is required because it limits the starting current to a safe value.
asked
Mar 20, 2018
by
anonymous
Answer :
The starting winding of a single-phase motor is placed in stator.
asked
Mar 20, 2018
by
anonymous