Motor self-starting circuit

In some production situations, it is required that the motor can start automatically after power failure to make the equipment run. The following figure is a typical circuit that can realize self-starting control.

The circuit uses a time relay and an intermediate relay to achieve self-starting. Press "SB1", the contactor "KM" is energized and self-locked, and the motor "M" starts to run. At the same time, the power-off delay relay "KT" is energized, and its power-off delay disconnected moving contact KT (1-3) is closed. Under normal circumstances, press "SB2", the intermediate relay K (is energized, its moving and breaking contacts K (55-7) are disconnected, "K" and "KT" lose power, and the motor M stops. When the power is off, "K", "KM", and "KT" all lose power. If the KT power-off delay time has not expired, the closed power-off delay disconnected contact KT (1-3) has not been disconnected. At this time, when the power is on again, the motor M starts to run through the contact KT (1-3).