1. Disconnect the power supply, check the frame of the control cabinet for reliable grounding, and make the grounding resistance is not greater than 4 Ω.

2. The control has different voltage (110 v dc, ac single-phase 220 v, three-phase ac), the circuit must be noted during maintenance, prevent short circuit accident.

3. Control on all electrical switches, action should be flexible and reliable, and no significant noise, cable knot and terminal should be no loose phenomenon, the dynamic contact wire cable knot place should be no fracture phenomenon.

4. Clear the screen with a soft brush or blowing plug-in and all electromagnetic switch components of dust, and check in control cabinet electrical switch contact state, contact conditions, the insulation of the coil appearance and whether the action of mechanical parts and reliable.

5. Replace the fuse, fuse current match the current of the circuit.