How can a synchronous motor be made to have a leading power factor?
A Synchronous Motor can be made to operate at unity and leading power factor by just increasing its excitation voltage i.e. by increasing the field current. This advantage of Synchronous Motor is used to improve the power factor.
Does a synchronous motor have a leading power factor?
The synchronous motor supplies a unity or leading factor, and an induction motor provides a unity or lagging factor. By applying the proper amount of DC excitation to the field poles of a synchronous motor, it operates at unity power factor.
What if the synchronous motor is operated in leading power factor?
A synchronous motor running with no load will lead the current i.e. leading power factor like a capacitor. This synchronous motor running without load i.e. over excited is synchronous condenser.
Under what condition does a synchronous motor take a leading current?
Synchronous motor takes leading current when it is overexcited or under excited.
Why there is no slip in synchronous motor?
Because the rotor turns at the same speed as synchronous speed (speed of the rotating magnetic field), there is no slip. The speed of rotation of the motor is constant in a synchronous motor, and does not vary with load, as in an induction motor.
Why synchronous motors are not self starting?
Above a certain size, synchronous motors are not self-starting motors. This property is due to the inertia of the rotor; it cannot instantly follow the rotation of the magnetic field of the stator. … Once the rotor nears the synchronous speed, the field winding is excited, and the motor pulls into synchronization.
How can synchronous motor be stopped?
The methods that are employed for Braking of Synchronous Motor are:
- Regenerative braking while operating on a variable frequency supply.
- Rheostatic braking.
How does changing excitation current affect a synchronous motor?
One of the most important features of a synchronous motor is that by changing the field excitation, it can be made to operate from lagging to leading power factor. Consider a synchronous motor having a fixed supply voltage and driving a constant mechanical load. … hence the power factor cos of the motor changes.
What is excitation EMF?
The process of generating a magnetic field by means of an electric current is called excitation. Field coils yield the most flexible form of magnetic flux regulation and de-regulation, but at the expense of a flow of electric current.
What is the difference between alternator and synchronous motor?
The synchronous generator or Alternator is a machine for converting the mechanical power from a prime mover to an AC electrical power at a specific voltage and frequency. … For bulk power generation large alternator is used in the thermal, hydro and nuclear power station.
What is the advantage of synchronous motor?
The advantage of using synchronous motor is the ability to control the power factor. An over excited synchronous-motor has leading power factor and is operated in parallel to induction motors thereby improving the system power factor. Speed remains constant irrespective of the loads in synchronous motors.