Motor multi-protection control circuit

The motor multi-protection starting circuit is a circuit in which the motor can only start when the peripheral auxiliary equipment meets the working requirements. For example, SQ in this figure is a limit switch that plays a role in position protection. If the auxiliary equipment does not meet the position requirements, the motor cannot start. According to work needs, it can also be multiple controls such as pressure, temperature, and liquid level. When multiple protections are required, the normally open contacts of various auxiliary protection devices can be connected in series.

The starting process of the motor multi-protection starting circuit is to close the QF switch circuit to get power, but at this time the SB2 start button does not work because the SQ normally open contact of the auxiliary protection is not closed. Only when the auxiliary equipment reaches the position requirement, the SQ normally open contact is closed and the SB2 button works. If the position of the auxiliary equipment changes during operation, the SQ contact is immediately disconnected, the KM contactor coil is de-energized and released, and the KM contactor main contact is disconnected and the motor stops running. Thus, the purpose of protection is achieved.