Fault phenomenon: the equipment can be started, but the voltage rise is not high, which is easy to produce overcurrent or overvoltage fault. At the same time, it can be observed that the phase failure light flashes.

Fault analysis and treatment: there is a problem with the three-phase incoming power supply.

a. One contact of the incoming contactor is not in good contact. When the voltage is applied, the armature suction is weakened, resulting in phase loss.

b. For high-power power supply, one contact of incoming circuit breaker is not well contacted.

c. The synchronous signal line introduced by the rectifier thyristor has poor contact.

d. The contact at the high-voltage end is not in good contact, and there is arcing discharge.