0
The 3 phase supply is provided in the stator of a synchronous motor which produces a rotating magnetic field.The stator has field poles(North and south). Now due to the rotating magnetic field the current is induced in the rotor of the motor as due to ampere's law, so the motor tends to move.Now as the stator poles induces opposite poles on the rotor, after moving the first pole pitch the rotor gets repelled by the opposite stator poles and due to the heavy inertia of the rotor it can't respond and the motor is standstill.Hence the synchronous motor is started with the help of an auxiliary motor or such called a pony motor to overcome this problem.
Wiki User
∙ 12y ago
Add your answer:
Earn +20 pts
Why synchronous motor is not a self starting motor?
As per the operating principle of the Synchronous motor, due to continuous & rapid rotation of stator poles,the rotor is subjected to a torque which is rapidly reversing i.e. in quick succession,the rotor is subjected to torque which tends to move it first in one direction & then in the opposite direction.Owing to its large inertia,the rotor cannot instataneously respond to such quickly-reversing torque,with the result that it remains stationary or in other words it is not self starting.
Why use clutch plate in single phase motor?
induction motors have very little starting torque as the motor come up to speed it reduces the torque load until it gets near synchronous speed
Drawing of speed-torque curve for synchronous machine?
Theoritical torque speed curve for a synchronous machine will be a vertical line located vertical to the synchrounous speed at x axis, from starting torque to stalling torque value. This is because theoritically synchronous motors are not self starting. Practically however they start as induction motors and at near synchrounous speed the excitation is switched on. Anand Sekhar
How does the starting of synchronous motor using dc generator as a load work-?
Starting of the synchronous motor using the DC generator creates a magnetic field.
Why synchronous motors does not have starting torque?
Becoz it use frequecy to start
What is reluctance torque?
torque of synchronous motor with out feild exitation
Why synchronous motor is not a self starting motor?
As per the operating principle of the Synchronous motor, due to continuous & rapid rotation of stator poles,the rotor is subjected to a torque which is rapidly reversing i.e. in quick succession,the rotor is subjected to torque which tends to move it first in one direction & then in the opposite direction.Owing to its large inertia,the rotor cannot instataneously respond to such quickly-reversing torque,with the result that it remains stationary or in other words it is not self starting.
What is synchronous machein?
mainly alternator,synchronous motor comes under the synchronous machine.a synchronous motor is not a self starting motor.if a synchronous motor moves with more than synchronous speed then it acts as a synchronous generator.
What are the advantages of induction motor?
1. Induction motor has high starting torque, therefore use for operate pump which need high starting torque. 2. Induction motor operate on variable speed. 3. It can be used as generator when speed of motor is higher than synchronous speed.
Why use clutch plate in single phase motor?
induction motors have very little starting torque as the motor come up to speed it reduces the torque load until it gets near synchronous speed
Drawing of speed-torque curve for synchronous machine?
Theoritical torque speed curve for a synchronous machine will be a vertical line located vertical to the synchrounous speed at x axis, from starting torque to stalling torque value. This is because theoritically synchronous motors are not self starting. Practically however they start as induction motors and at near synchrounous speed the excitation is switched on. Anand Sekhar
How does the starting of synchronous motor using dc generator as a load work-?
Starting of the synchronous motor using the DC generator creates a magnetic field.
How floating condition of synchronous motor occurs?
at the time of starting when syncchronous torque is zero , i.e. when the motor starts with the help of starting torque , the armature current required to produce sync. torque is zero. If V = E(b) i.e. When back emf E(b) equals supply voltage.
Why is the speed of synchronous motor is more then induction motor?
Synchronous motors run at synchronous speed. An induction motor that has the same number of poles must run at a sub-synchronous speed to create a second magnetic field (a field that is at a different phase angle) to generate torque.
Why synchronous motors does not have starting torque?
Becoz it use frequecy to start
Why synchronous motor is not self starting?
As per the operating principle of the Synchronous motor, due to continuous & rapid rotation of stator poles,the rotor is subjected to a torque which is rapidly reversing i.e. in quick succession,the rotor is subjected to torque which tends to move it first in one direction & then in the opposite direction.Owing to its large inertia,the rotor cannot instataneously respond to such quickly-reversing torque,with the result that it remains stationary or in other words it is not self starting.
Performance curve of a single phase induction motor?
The performance curve can be a graph of torque versus speed. The torque is zero at zero speed and also at the synchronous speed. Normally an induction motor operates at 90-97% of the synchronous speed, where the slip is between 10% and 3%. In this region the torque is proportional to the slip. As the torque is increased the speed falls until the motor stalls and the speed drops to zero. Below the stalling speed the torque rises between zero speed and the stalling speed. Because the torque is 0 at 0, a single-phase induction motor needs a separate starting winding fed by a starting capacitor to produce a little positive torque that starts the motor.
