Industry News

Matters needing attention during outdoor distribution box operation

2021-09-22
1. The high temperature causes the service life of the electrical equipment of the distribution box to decrease
The upper limit of the ambient temperature of electrical equipment designed and manufactured in accordance with the national standard should not exceed 40 ℃, and the operating distribution box exposed to the scorching sun in summer is due to the direct sunlight, the reflection of the heat from the cement floor and the equipment inside the box. The heat generated by itself sometimes exceeds 60°C in the box. Such a high temperature can easily cause the insulation of electrical coils and leads to breakdown and burn out; the electrical contacts increase contact resistance due to the high temperature, and the increase in contact resistance increases fever. Such a vicious cycle will eventually cause the contacts to burn out; at the same time; Too high temperature will also affect the stability of electrical protection functions, the reliability of actions, and the accuracy of measurement.
2. Install the lightning arrester only on the incoming line side, the lightning protection cannot cover the whole equipment

Generally, fuse and other equipment are installed between the incoming and outgoing wires of the distribution box and its bus. When the outgoing wire is struck by lightning, if the incoming fuse is blown first, all the distribution boxes will lose lightning protection. Every year, there are many The distribution box was damaged by lightning.

3. Improper installation process causes overheating and burning of the connector

Some electricians do not press the wire lug when changing the lead wire, and use a multi-stranded wire to wind the wire lug for screw connection. As a result, the lead wire is burnt shortly after the wire is changed. The distribution box produced by some manufacturers is connected to the bus by the branch line stacking and screw connection, and the heat dissipation is not good, and the heavy load naturally constitutes a continuous failure.
4. The distribution box is put into use without inspection, leaving hidden dangers to safety
Although the products provided by the equipment manufacturer have been strictly inspected before leaving the factory, due to bumps in the road and vibration during loading and unloading, some of the connecting bolts may show a certain degree of looseness after being delivered to the site, causing some outdoor distribution boxes to be put into operation. Soon there was overheating of the lead joints.
5. Improper installation location of the distribution box will not only affect the appearance of the city, but also be easily damaged by external forces. It is recommended to choose an appropriate installation location based on comprehensive consideration.

6. Some protective zero-connection power supply systems still use three-phase four-wire power supply. The zero line of the low-voltage power grid is longer and the impedance is large. When the three-phase load is unbalanced, there will be zero-sequence current passing through the zero line. Environmental deterioration, wire aging, moisture and other factors, the leakage current of the wire also forms a closed loop through the neutral wire, which causes the neutral wire to have a certain potential, which is very unfavorable for safe operation.

7. The distribution box is too small, the gap between the electrical appliances and the phases is small, and some have no obvious disconnection points, which not only brings danger to the electrician operation, but also makes it impossible to change the fuse in rainy and foggy weather. Work; distribution boxes generally lack phase protection, and accidents that burn out the electromechanical equipment due to lack of phase occur from time to time; some distribution boxes do not use electronic watt-hour meters, and it is impossible to implement remote centralized meter reading; some distribution boxes are closed all year round. Therefore, there is a lack of routine inspection protection.