Electric hoist circuit

An electric hoist is a small lifting machine, mostly used for lifting equipment. It consists of two parts: a hook and a mobile crane. The lifting
and traveling of the hook are driven by an electric motor . The lifting motor drives the drum to rotate, thereby driving the hook to rise or fall. The traveling motor drives
the lifting mechanism to move horizontally on the I-beam, so that the brick-carrying crane moves forward or backward. Its appearance and control circuit are shown in Figure 2-16a and b.
    The main circuit uses circuit breaker QF for short-circuit protection. Contactors KMl and KM2 control the lifting electric gourd Ml, and KM3 and KM4 control the traveling motor
M2 to run forward and reverse. They all rely on changing the phase sequence applied to the three-phase power supply of the motor