# Often asked: How Synchronous Motor Works?

## How does a synchronous motor start?

The motor is first started as a slip ring induction motor. The resistance is gradually cut-off as the motor gains speed. When it achieves near synchronous speed, DC excitation is given to the rotor, and it is pulled into synchronism. Then it starts rotating as a synchronous motor.

## What is the working principle of synchronous generator?

The synchronous generator works on the principle of Faraday laws of electromagnetic induction. Electromagnetic induction states that electromotive force induced in the armature coil if it is rotating in the uniform magnetic field. The EMF will also be generated if the field rotates and the conductor becomes stationary.

## How synchronous motor works as a power factor correction?

The power factor of a synchronous motor is changed with a change in the excitation. When the excitation of the motor is increased, the power factor changes from lagging to unity and then to a leading power factor.

## What are the main characteristics of synchronous motor?

Characteristics of Synchronous Motor are constant speed motors. The speed of the motor is decided by the number of poles and frequency. Compared to an induction motor, it is very sensitive to sudden changes of load. This causes a hunting of the rotor and finally leads to stability problems.

## How do you know if a motor is synchronous?

In contrast, consider a synchronous motor. Here, the rotor turns at the same rate — that is, in synchronization — as the stator’s magnetic field. Like the induction motor, the synchronous ac motor also contains a stator and a rotor. The stator windings also connect to the ac power as in an induction motor.

## What are the advantages of synchronous motor?

The advantages of the synchronous motor are the ease with which the power factor can be controlled and the constant rotational speed of the machine, irrespective of the applied load. Synchronous motors, however, are generally more expensive and a d.c. supply is a necessary feature of the rotor excitation.

## What is synchronous speed?

Synchronous speed is a significant parameter for the rotating magnetic field-type AC motor. It is determined by the frequency and the number of magnetic poles. Synchronous speed No = [rps, revolutions per second] f = Frequency [Hz] p = Number of magnetic poles.

## What are the two types of synchronous generators?

Classification of Synchronous Generators | Electrical Engineering Hydroelectric Generators: The generators employed in hydroelectric power plants are three phase alternating current synchronous generators, called the alternators. Turbo Alternators: Diesel-Engine Driven Synchronous Generators:

## Why do we use synchronous generator?

Synchronous generators are the majority source of commercial electrical energy. They are commonly used to convert the mechanical power output of steam turbines, gas turbines, reciprocating engines and hydro turbines into electrical power for the grid. Some designs of Wind turbines also use this generator type.

## Why the synchronous motor is 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.

## Do synchronous motors have slip?

Do synchronous motors have slip? 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.

## What is the difference between synchronous motor and synchronous condenser?

The only difference between a synchronous motor and a synchronous condenser is the synchronous condenser shaft is not connected to anything—it simply spins unimpeded. The sole purpose of a synchronous condenser is to adjust conditions (power factor) on the electric power transmission grid.

## What is the main disadvantage of synchronous motors?

The disadvantages of Synchronous motor includes: Synchronous motors require dc excitation which is supplied from external sources. These motors are not self -starting motors and need some external arrangement for its starting and synchronizing. The cost per kW output is commonly higher than that of induction motors.

## What is difference between induction motor and synchronous motor?

A three-phase Synchronous motor is a doubly excited machine, whereas an induction motor is a single excited machine. The armature winding of the Synchronous motor is energized from an AC source and its field winding from a DC source. The stator winding of Induction Motor is energized from an AC source.