Automatic Star Delta Starter

Automatic Star Delta Starter Points : Automatic Star Delta Starter, Definition An automatic star-delta starter is shown. Automatic star delta starters usually embody an electronic timer with adjustable timing on the star connection and with a short but definite time delay at the change over.

When we press the ON push-button, the coil of main contactor (K1) is energized and at this instant the normally open contacts of a k1 are closed and formally closed contacts are open. The (NO) contact of K1 is in series of the coil of the K3 contacts as a result; the coil of star contactor is also, energized and main contacts of star contactor are closed and motor run in star connection. When star connector is energized, a normally open contact of star contactor is in series of timer, when this contact closed the timer is ON and started to count the adjustable time. After a definite period of time, the time-delay relay or timer open the circuit of star contactor (K3) and close the circuit of delta contactor (K2).The normally close contact of timer is in series of star contactor (K3) and .therefore when timer complete its adjustable time, its contacts position is changed and its normally open contacts are closed and normally closed contacts becomes open, when this condition occur motor run in delta connection. A normally closed contact of (K2) contactor is in series of timer circuit, when delta contactor (K2) energized, it open the timer circuit. In this circuit, this time only main contactor and delta contactor are in ON position. Timer and star contactors are out of circuit: