The star-delta starter has great application in the asynchronous motors with the short-circuit rotor. This type of system consists of connecting the stator windings to star and, when the motor starts, connect them in triangle, this being the most usual module of operation. This technique reduces the starting current to 1/3 of its value.
The schematic allows automatic start-up, so that after a certain time the delayed-action contactor -KM2 switches from one connection to another, ie from star to triangle.
Description of the operation of the power circuit:
Closing of -KM1 (star connection)
Closing of -KM2 (motor power)
Aber Opening of -KM1 (star connection elimination)
Closing of -KM3 (triangle connection)
Description of the operation of the control circuit:
Activation of the travel button 1
Closure of -KM1
Closing of -KM2 by -KM1 (auxiliary contacts 13-14)
Self-powering of -KM1 and -KM2 by -KM2 (contacts 13-14)
Opening of -KM1 by -KM2 (contacts 55-56)
Closing of -KM3 by -KM1 (contacts 11-12)
Stop: Press the stop button 0