(1) AC contactor may be short-circuited
1 Reversible conversion of the contactor interlock is unreliable. Due to malfunction, the two contactors are put into operation at the same time, causing phase-to-phase short circuit, or because the contactor moves too fast, the conversion time is short, and an arc short circuit occurs during the conversion process.
2 Dust accumulates or sticks with water vapor and grease, which deteriorates the insulation.
3 Product parts are damaged (such as the arc-breaking cover is broken).
(2) Treatment
1 Check the electrical interlock and the mechanical interlock, and add the intermediate link delay reversible conversion time on the control line.
2 Clean up often and keep it clean.
3 Replace damaged parts.
In short, due to the failure of the contactor's positive and negative interlocking, or the two contactors are put into operation at the same time due to malfunction, the phase-to-phase short circuit is formed; or because the contactor moves too fast, the switching time is short, and the arc short circuit occurs during the conversion process. In the case of such a fault, the contactor and the button composite interlock can be used to control the forward and reverse of the motor in the control circuit.
