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Why the back emf of ┬аSynchronous Motors is only depended on DC excitation?
It constant speed motor
it can operate at any power factor
it a doubly excited machine
it is not a self-starting motor
It constant speed motor
The back EMF of synchronous motors is solely dependent on the DC excitation because these motors operate at a constant speed determined by the supply frequency. The excitation affects the magnetic field strength, which in turn influences the generated back EMF.
The back EMF of synchronous motors is solely dependent on the DC excitation because these motors operate at a constant speed determined by the supply frequency. The excitation affects the magnetic field strength, which in turn influences the generated back EMF.
EbтАЛ=╬жтЛЕ╧Й тАФ where EbтАЛ is the back EMF, ╬ж is the flux, and ╧Й is the angular speed.
╬жтИЭIdcтАЛ тАФ where the flux is proportional to the DC excitation current.
Synchronous motors maintain a constant speed as their rotor synchronizes with the rotating magnetic field produced by the stator. The level of DC excitation determines the flux in the machine, which directly dictates the back EMF generated, keeping the motor speed constant regardless of the load.
Synchronous motors run at a speed determined by the supply frequency.
Back EMF is directly proportional to the flux created by DC excitation.
High efficiency in steady-state operation.
Ability to maintain a constant speed under varying loads.
Not self-starting, requiring additional mechanisms to start.
Requires precise control of excitation for optimal performance.
Used in applications requiring precise speed control like generators.
Common in power plants and industrial applications.
In synchronous motors, the constant speed is dictated by the supply frequency regardless of load variations.
Option B is incorrect as synchronous motors can operate at only one power factor depending on the excitation.
A is correct тАФ Synchronous motors maintain constant speed as they synchronize with the supply frequency, which is primarily controlled by DC excitation.
Understand the relationship between DC excitation, back EMF, and the operating speed of synchronous motors, as these concepts often overlap in electrical machine exams.