Why Star delta starter is used in motor?

Most Induction motors start directly on the line, but when too many HP motors start this way, they initially cause voltage troubles on the supply lines due to over-voltage. To reduce the starting current of the motors, the motors of more HP are run at a lower starting voltage and then reconnected to the full supply voltage when the rotational speed is reached. This work is done by Star Delta starter.

Star Delta Conneection

                                        

Principle of working Star-Delta Starter

                               

There are two methods used for initial voltage reduction: 1. Star Delta starting and 2. Auto Transformer starting. Star Delta Starter is the method of starting the motor at low voltage. More HP motor takes more load in the beginning, due to which the motor is expected to burn, we use Star – Delta starter to avoid burning it. This starts the starter motor in the first star, in the star the motor is run at a low starting voltage.

Star Delta Circuit Diagram

                          

 After running a few seconds the motor enters the automatic delta by the starter and the motor starts running at its normal speed. The starter is used to operate the safety and accessibility of the motor and reduce disturbances and interference on the power supply Used as a means of reducing the flow of current applied to the motor during starting

This Star-Delta starter is used to operate motors with power greater than 5 HP. This makes the motor run in star-combination at 58% voltage of full voltage. When the motor attains speed, it combines it into a delta.

MORE DETAILS:-

Induction Motor:-Click Here