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The synchronous motor is made self starting by providing a special winding on the rotor poles, known as damper winding or squirrel cage winding. AC supply given to the stator produces a rotating magnetic field which causes the rotor to rotate, therefore, in the beginning synchronous motor provided with damper winding starts as a squirrel cage induction motor. The exciter moves along the rotor. When the motor attains about 95%of synchronous speed, the rotor winding is connected to exciter terminals and the rotor is magnetically locked by the rotating field of the stator and the motor runs as a synchronous motor.
While starting a synchronous motor, the field winding must be shorted through a suitable resistance so that the induced voltage is distributed throughout the whole winding and no part is subjected to the high voltage induced in the entire winding.
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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.
Speed control method for synchronous motor?
True synchronous mode and self control mode
What is self control of synchronous motor drive?
the self control of a synchronous motor is done using an inverter fed through a dc link.speed is controlled by varying the output frequency of the inverter by controlling the dc link voltage
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.
What is runaway speed of synchronous machine?
A synchronous electric motor is an AC motor in which the rotation of the shaft is synchronized with the frequency of the ACsupply current; the rotation period is exactly equal to an integral number of AC cycles. Synchronous motors contain electromagnetson the stator of the motor that create a magnetic field which rotates in time with the oscillations of the line current. The rotor turns in step with this field, at the same rate.Another way of saying this is that the motor does not rely on "slip" under usual operating conditions, and as a result produces torque at synchronous speed. Synchronous motors can be contrasted with induction motors, which must slip in order to producetorque. The speed of the synchronous motor is determined by the number of magnetic poles and the line frequency.Synchronous motors are available in sub-fractional self-excited sizes to high-horsepower direct-current excited industrial sizes. In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. In high-horsepower industrial sizes, the synchronous motor provides two important functions. First, it is a highly efficient means of converting AC energy to work. Second, it can operate at leading or unity power factor and thereby provide power-factor correction.
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.
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.
Speed control method for synchronous motor?
True synchronous mode and self control mode
What is self control of synchronous motor drive?
the self control of a synchronous motor is done using an inverter fed through a dc link.speed is controlled by varying the output frequency of the inverter by controlling the dc link voltage
Principle and working of synchronous motor?
Principle of synchronous motor is as given below:"when a 3 phase winding is fed by a 3 phase supply, then a magnetic flux of constant magnitude but rotating at synchronous speed, is produced."
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.
Why 3 phase induction motor is self starting but synchronous motor is not?
the induction motor as soon as you turn on the power the rotating magnetic field is set up. the shorted winding in the squirrel cage see this and builds up a temporary magnet when its up to synchronous speed there is no longer current in the shorted winding in a single pole motor 60hz this speed is 3600 rpm depending on coupling and skew induction motor is always less than synchronous speed. the synchronous motor as soon as you turn on the power the rotating magnetic field is set up the permanent magnet 0 to 3600 rpm in 1/60th of a second this requires all the power you can deliver until you reach synchronous speed a bit hard on the power source smaller synchronous motors sometimes have a squirrel cage and permanent magnets and enough impedance so they dont put a heavy load on the power electric clocks have the shorted windings on the poles self starting hi impedance some older electric clocks didnt have the shorted windings and need to be nudged to get then spinning
What is Commutatorless DC Motor?
A commutator less DC motor is nothing but a self controlled synchronous motor is being widely used in industries for high speed and large capacity.
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 induction motor is made self starting?
just put a auxilari winding on the rotor (in the salient pole)..
What is the starting method of synchronous motor?
There are 5 types of starting in induction motors: 1) resistance variable method 2) auto transformer method 3) slip ring induction motor method Squirrel cage induction motor using two types of starting methods 1.Direct on line starter 2.Star delta starter
Is a three phase induction motor self starting?
A three-phase motor has a steady rotating magnetic field generated by the stator coil, and the rotor just follows the field.
