1. Disconnect the power supply and check that the cabinet of the control cabinet has a reliable grounding and that the grounding resistance is not more than 4 Ω.
2. There are voltages of different nature on the control cabinet (DC 110V; AC single-phase 220V; three-phase AC), the circuit must be separated during maintenance to prevent short-circuit accidents.
3. All electrical switches on the control cabinet should be flexible and reliable, no significant noise, no looseness at the junction of the connecting wire and the terminal, and there should be no breakage at the wire at the junction of the moving contact.
4. Use a soft brush or blower to remove the dust from the panel insert and all the electromagnetic switch parts, and check the status of the electrical switch contacts in the control cabinet, the contact conditions, the insulation of the coil appearance and the action of the mechanical components.
5. When replacing the fuse, the fuse current should match the current of the loop.