1. Move your mouth before you start

For faulty electrical equipment, do not rush to start, but first inquire about the process before and after the fault and the fault phenomenon. For unfamiliar equipment, you should first be familiar with the circuit principle and structural characteristics and abide by the corresponding rules. Before disassembly, be fully familiar with the function, position, connection mode of each electrical component and its relationship with other surrounding devices. If there is no assembly drawing, draw a sketch and mark while disassembling.

2. From outside to inside

Check the equipment for obvious cracks and defects, understand its maintenance history and service life, and then check the inside of the machine. The surrounding fault factors shall be eliminated before disassembly, and the disassembly can be carried out only after it is determined that it is an internal fault. Otherwise, the blind disassembly may cause the equipment to get worse and worse.

3. Mechanical before electrical

The electrical inspection shall be carried out only after it is determined that the mechanical parts are free of fault. When checking the circuit fault, the detection instrument shall be used to find the fault position. After confirming that there is no poor contact fault, the operation relationship between the line and the machinery shall be checked to avoid misjudgment.

4. Static before dynamic

When the equipment is not powered on, judge the quality of buttons, contactors, thermal relays and fuses of electrical equipment, so as to determine the fault. Power on test, listen to its sound, measure parameters, judge faults, and finally carry out maintenance. For example, when the motor is out of phase, if the measured three-phase voltage value cannot be distinguished, you should listen to its sound and measure each phase to ground voltage separately, so as to judge which phase is out of phase.

5. Cleaning before maintenance

For heavily polluted electrical equipment, first clean its buttons, wiring points and contact points, and check whether the external control keys fail. Many faults are caused by dirt and conductive dust. Once cleaned, the faults are often eliminated.

6. Power supply before equipment

The failure rate of power supply accounts for a high proportion in the whole faulty equipment, so it is often possible to get twice the result with half the effort to overhaul the power supply first.

7. General before special

Faults caused by assembly parts quality or other equipment faults generally account for about 50% of common faults. The special faults of electrical equipment are mostly soft faults, which need to be measured and maintained by experience and instruments. For example, a 0.5KW motor is considered to be a load fault because it cannot carry a dynamic load. According to experience, wear thickened gloves and grasp along the rotation direction of the motor. As a result, it is grasped. This is the problem of the motor itself.

8. From the outside to the inside

Do not rush to replace the damaged electrical components, and consider replacing the damaged electrical components when confirming that the peripheral circuit is normal.

9. DC before AC

During maintenance, the static working point of DC circuit must be checked first, and then the dynamic working point of AC circuit must be checked.

10. debug after failure.

For the electrical equipment with both commissioning and fault, the fault shall be eliminated before commissioning. The commissioning must be carried out on the premise that the electrical circuit is normal.