What factors determine the speed of a synchronous motor?
The synchronous speed of an AC motor is determined by the frequency of the source and the number of poles. The RPM is calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles.
What happens when synchronous motor is under Excited?
Synchronous motor: … Lagging power factor: If field excitation is such that Eb < V the motor is said to be under excited and it has a lagging power factor. Leading power factor: If field excitation is such that Eb > V the motor is said to be over-excited and it draws leading current.
What is the effect of under excitation and over excitation on the synchronous motor?
The over-excitation limiter protects the generator against over-temperature caused by high field current for long time. Under-excitation limiter prevents the decrease of generator field current to the values lower than the stability margin or the thermal limit of end side of the stator core.
Why does synchronous motor runs at synchronous speed?
synchronous motor, alternating-current electric motor designed to run at a speed that is directly proportional to the frequency of the electric power source. The rotor’s magnetic field tends to align with the rotating field produced by the three-phase alternating currents in the stator. …
When excitation is increased over excitation the synchronous generator operates at?
In synchronous generator, inverted V curve is drawn between field current on X-axis and power factor on Y-axis. At critical excitation the power factor is unity. If excitation is decreased, the generator operates at leading power factor and if excitation is increased, the generator operates at lagging power factor.
What are the factors affecting the synchronous speed?
The speed of a synchronous motor is dependent on the frequency of the power source and the number of poles the stator has. RPM increases directly with frequency and inversely as the number of poles. The same formula used to calculate the speed of the induction motor is used to determine the speed of this type of motor.
How can we increase the speed of synchronous motor?
We can control the speed of the synchronous motor by changing the frequency of the supply to the motor.
What are the conditions for reading synchronous speed?
The speed of the rotating stator field is called the synchronous speed. The frequency of the power supply and the number of poles of the machine determine the synchronous speed. A synchronous motor is one in which the rotor turns at the same speed as the rotating magnetic field in the stator.
Why exciter is essential for synchronous motor?
The exciter provides the power to the electromagnets that form the poles on the rotor that in turn follow the rotating magnetic field from the system.