Commutation circuit for three-phase motors to prevent phase-to-phase short circuit

When switching between forward and reverse rotation of the motor, serious arcing occurs on the main contact of the contactor due to operation or some reason. If the reverse AC contactor closes before the arc is completely extinguished, it is likely to cause a phase-to-phase short circuit. In the circuit shown in the figure, an AC contactor KM is added to solve the problem of phase-to-phase short circuit. When the forward and reverse directions are reversed, after the forward contactor KMF is powered off, the contactor KM (that is, the newly added) is also disconnected. In this way, there are four breakpoints to extinguish the arc, which can effectively extinguish the arc and avoid phase short circuits. Fault.