In order to ensure the normal and safe operation of low-voltage distribution cabinet and equipment control cabinet, the maintenance group of mechanical and electrical installation and maintenance engineering department shall conduct a comprehensive inspection and maintenance of low-voltage distribution cabinet every six months.

1. Preparation:

A. Inform the residents of the starting and ending time of power failure one day before the maintenance of power distribution cabinet

B. Make all preparations before power failure, ensure complete tools, and complete maintenance in the shortest power failure time

2. Maintenance procedure

A. Carry out sectional maintenance, maintain the security load section first

B. Turn off the power supply of the security load, and the rest of the load will be supplied as usual. Turn off the air switch of the security load, turn off the air switch of the generator, put the generator selection switch in the stop position, disconnect the positive and negative wires of the battery, and hang up the sign board to prevent the generator from sending electricity

C. Check whether there is deformation at the bus joint, whether there is discharge blackening trace, and fasten the connecting bolt. If the bolt is rusty, it should be replaced to ensure that the joint is connected tightly. Check the insulation of the equipment for looseness and damage.

D. Use the handle to shake the total air out of the distribution cabinet, check whether the main contact has burning traces, check whether the arc extinguishing cover is burned black and damaged, tighten the wiring screws, clean the dust in the cabinet, and test whether the closing and opening of the machine are normal

E. Take out the separate closed cabinet from the drawer cabinet and fasten the wiring terminals. Check the installation and wiring of current transformer, ammeter and watt hour meter, and check the flexibility and reliability of handle operating mechanism. Fasten the inlet and outlet wires of air switch. Clean the dust in the switch cabinet and at the outlet wires behind the distribution cabinet.

F. When maintaining the capacitor cabinet, disconnect the capacitor main switch first, discharge the capacitor to ground one by one with a conductor of more than 10mm2, then check whether the contactor, capacitor connection screw and grounding device are good, check whether the capacitor has bulging phenomenon and clean the dust in the cabinet with a vacuum cleaner.

G. After the maintenance of the security load section, the generator can be started to supply power to it. The bus section of the power supply and maintenance of the power supply can be stopped.

H. Disconnect the air switch at the low voltage side step by step, then disconnect the vacuum circuit breaker at the high voltage side which provides the power of the transformer, close the grounding switch, and hang the sign “no closing, working for someone”

I. After the maintenance of the distribution cabinet is completed according to the c.d.e.f.  steps. Remove the safety device, disconnect the grounding switch on the high voltage side, close the vacuum circuit breaker, observe that the transformer is put into operation, and then gradually send power to the low voltage distribution cabinet, and transfer the security load from the generator power supply to the municipal power supply.

Safety precautions for maintenance of low voltage distribution cabinet and control cabinet:

1. Check the power after power failure.

2. When the power distribution cabinet is maintained in sections, isolation devices shall be installed at the junction of live and dead power distribution cabinets.

3. When operating the vacuum circuit breaker at the high voltage side, it is necessary to wear insulating boots, gloves and special personnel to monitor.

4. When maintaining the capacitor cabinet, do not touch the capacitor before discharging to the ground.

5. After maintenance, check whether there are tools left in the distribution cabinet before power transmission.