# Question: How To Make Synchronous Motor?

## Can synchronous motor start by itself?

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.

## What is a synchronous motor and how does it work?

A synchronous motor is one in which the rotor normally rotates at the same speed as the revolving field in the machine. The stator is similar to that of an induction machine consisting of a cylindrical iron frame with windings, usually three-phase, located in slots around the inner periphery.

## How do you start a 3 phase synchronous motor?

When a three phase supply is connected to the stator, the synchronous motor with Damper Winding will start. It works as a three – phase induction motor. As soon as the motor approaches the synchronous speed, the DC excitation is applied to the field windings.

## What is the construction of synchronous motor?

The construction of a synchronous motor (with salient pole rotor) is as shown in the figure at left. Just like any other motor, it consists of a stator and a rotor. The stator core is constructed with thin silicon lamination and insulated by a surface coating, to minimize the eddy current and hysteresis losses.

## Which motors are not self starting?

The stator carries windings connected to an AC supply to produce a rotating magnetic field.At synchronous speedthe rotor poles lock to the rotating magnetic field, beacause of the constant magnetic field in the rotor these cannot use induction windings for starting. Synchronous motors are inherently not self starting.

## 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.

## 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 is the formula for synchronous speed?

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 are the applications of synchronous motor?

Synchronous motors are normally used in applications in which a constant and precise speed is required. Typical applications of these low power motors are positioning machines. They are also used in robot actuators. Synchronous motors are also used in ball mills, watches, record players, and turntables.

## How can a synchronous motor be self starting?

Synchronous motor is not self starting but the damper winding makes it self starting. Damper winding is provided on the rotor of the synchronous motor. First step is to de-energize the field winding by shorting it through a suitable resistor and then connect stator of synchronous motor to three phase supply.

## What could be the reasons if a 3 phase synchronous motor fails to start?

What could be the reasons if a synchronous motor fails to start? Voltage may be too low. Some faulty connection in auxiliary apparatus. Too much starting load. Open circuit in one phase or short circuit. Field connection may be excessive.

## 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 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.