Due to improper selection of AC contactor capacity during manufacturing, AC contactors with the same capacity are installed for different outgoing circuits, and the imbalance of three-phase load is not considered, so the current level of some outgoing contactors is not increased by one current level on the basis of normal model selection, and the low-voltage electrical appliances in the distribution box are selected from fuses, AC contactors It is composed of residual current action protector, capacitor and meter. The upper limit of ambient air temperature shall not exceed 40 ℃; The average value of ambient air temperature in 24h shall not exceed 35 ℃; The lower limit of ambient air temperature shall not be lower than - 5 ℃ or - 25 ℃.

When the distribution box operates outdoors, it will not only generate high temperature under the direct sunlight, but also generate heat during operation. Therefore, in the high-temperature season in midsummer, the temperature in the box will reach more than 60 ℃, which greatly exceeds the specified ambient temperature of these electrical appliances

Installation skills of distribution cabinet:

1. Insulated wires shall be used for connecting wires, and there shall be no leakage parts. The working zero line shall be connected through the terminal board, which shall be set separately from the protective zero line terminal board. Metal cabinets, electrical mounting plates and electrical appliances shall not have live metal bases, and the shell must be provided with neutral connection measures.

2 the incoming and outgoing ports of conductors must be installed under the distribution cabinet, but not on the top, side or back. The incoming and outgoing lines shall be sheathed and bundled as waterproof bends; It is forbidden to connect the power line of the switch cabinet with bolts; The harness shall not be in direct contact with the inlet and outlet of the cabinet; The import and export lines of mobile equipment must use insulated rubber cables.

3 the equipment shall be installed in a ventilated and dry place at normal temperature. It is strictly prohibited to install and use in gas, flue gas, steam, liquid and vulnerable environment. There shall be enough space and passage around the equipment for two people to work at the same time, and sundries irrelevant to the work shall not be stacked around the equipment.

4 Graded power distribution shall be implemented on the construction site. The distribution cabinet shall be set below the main distribution cabinet, the switch cabinet shall be set below the distribution cabinet, and the electrical equipment shall be set below the switch cabinet.