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Why is the rotor winding of a synchronous motor connected to an external resistance during start up?
Wiki User
∙ 8y ago
because at start the motor draws larger quantity of current and this may affected the rotor windings
in order to limit current always resistance is connected.
Vivien Cassin
The external resistance connected to the rotor winding of a synchronous motor during start-up helps to limit the current flow and provide a higher starting torque. This is because when a synchronous motor is initially energized, it may not generate enough back EMF to prevent the current from exceeding the motor's rating. The external resistance helps to control and balance the currents flowing through the stator and rotor, ensuring a smooth start-up. Once the motor reaches synchronous speed, the external resistance is usually removed.
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Why armature winding resistance is less than field winding resistance?
An 'armature winding' is the rotor winding, and the 'field winding' is the stator winding.
Does a step-up transformer have a higher primary or secondary resistance?
It is a step up transformer since the secondary windings are greater than the primary. the turns ratio is (primary to secondary) 1:5, so the primary voltages is 1/5 of the secondary (5 volts).
Which winding has the higher resistance start or run in single phase motors?
start winding is thicker with less number of winding whereas run winding is less thicker than start winding but with more number of winding. As we know inductance depends upon numbers of turns of winding so run winding will have more inductance.
What are the uses of damper winding s in synchronous motor?
to achive constant speed and provide a eassy way to inter loacking with syn fluxDamper winding is a short circuited winding which are useful in preventing the hunting(momentary) speed fluctuation in alternator and are needed in synchronous motor to provide starting torque.
Is there any other method of damping the oscillation in a synchronous motor other than using damper winding and if yes what is it?
In synchronous motor hunting can be minimized using flywheel to the shaft .
Why the rotor winding of a synchronous motor is usually connected to an external resistance during start up?
because at start the motor draws larger quantity of current and this may affected the rotor windings in order to limit current always resistance is connected.
Why armature winding is star connected for synchronous motor?
Because your momma said so
How is the synchronous motor made self starting?
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.
What precautions should be taken during the start-up period of a synchronous motor?
Reduce the speed of the stator magnetic field.Use an external prime mover to accelarte the synchronous motor upto synchronos speed.Use damper windings.
What is synchronous reactance in alternator?
The overall reactance of the armature winding is the sum of its leakage reactance plus fictitious reactance, which is known as synchronous reactance (Xs).Xs=XL+Xarwhere XL and Xar are in Ω/phase. Therefore, Xs is in Ω/phase.The impedance of armature winding is obtained by combining its resistance and its synchronous reactance.
Why armature winding resistance is less than field winding resistance?
An 'armature winding' is the rotor winding, and the 'field winding' is the stator winding.
What is an amortisseur winding?
An amortisseur winding is a squirrel cage winding placed near the surface of the pole faces of a synchronous motor.
How is the resistance of a motor winding expressed?
The resistance of a motor winding is expressed in
The primary winding in a transformer is connected to the what?
The primary winding of a transformer is connected to the supply, while the secondary winding is connected to the load.
Does a step-up transformer have a higher primary or secondary resistance?
It is a step up transformer since the secondary windings are greater than the primary. the turns ratio is (primary to secondary) 1:5, so the primary voltages is 1/5 of the secondary (5 volts).
Which winding has the higher resistance start or run in single phase motors?
start winding is thicker with less number of winding whereas run winding is less thicker than start winding but with more number of winding. As we know inductance depends upon numbers of turns of winding so run winding will have more inductance.
How can you distinguish the primary from secondaty side on a transformer?
Whichever winding is connected to the supply is the primary winding; whichever winding is connected to the load is the secondary winding.
