1. The three-phase voltage indication is unbalanced: it may be damaged by insurance.
2. The neutral point is not grounded: the three-phase is unbalanced, which may be resonance or affected by the arc suppression coil.
3. High-voltage insurance fuse repeatedly: internal insulation damage, inter-layer and inter-turn failure.
4. Neutral grounding, voltage fluctuation: If the operation is series resonance, the internal insulation is damaged if there is no operation.
5. Unstable voltage indication: bad grounding, timely check and deal with.
6. Circuit disconnection of voltage transformer: exit protection, check insurance and replace, check circuit.
7. Abnormal sound: The electromagnetic unit reactor or intermediate transformer is damaged.