STARTING OF INDUCTION MOTORS

Types of starters

There are five types of starting of induction motor.

1. Srator resistance starter

2. Autotransformer starter

3. Star-Delta starter

4. Rotor resistance starter

5. Drirect on line starter. 

Let us study the details of each of these starters.

Stator Resistance Starter

In order to apply the reduced voltage to the stator of the induction motor, three resistances are added in series with each phase of the stator winding. Initially the resistances are kept maximum in the ckt. Due to this large voltage get dropped across the resistance. Hence a reduced voltage gets applied to the stator which reduces the high starting current. The schematic diagram showing stator resistance in shown in fig

                                                               Stator resistance starter

When the motor starts running, the resistance are gradually cut-off from the stator ckt.

When the resistance are entirely removed from the stator ckt .That is rheostats in run position then rated voltage gets applied to the stator. Motor run with normal speed.

The starter is simple in construction and cheap.

It can be used for both star and delta connected starter.