What is Star to Delta Starter?

Why we need star delta starter ?

  1. Initial current can be 4 times higher than the normal load current . 2.Very heavy torque on motor 3.Large contactor and cable size required to run directly in delta mode.

Solution - Initially run motor in star mode and then in delta mode

Working :

Star mode -

Contactor Q1 and Q2 will be on and Q3 will be off.

Delta mode

Contactor Q1 and Q3 will be on and Q2 will be off

Control circuit for Start to Delta Starter