发布时间：2024-01-22 来源：/ 浏览量：
1. High temperature causes a decrease in the service life of electrical equipment in distribution boxes
按国标设计和制造的电气装备运行时周围环境温度的上限值不应超过40℃，而夏天暴露在烈日中的运行配电箱，因为太阳光的直射、水泥地面热量的 反射和箱内装备本身发生的热量，有时箱内的温度竟超过60℃。如此高的温度极易造成电器线圈、引线的绝缘老化而击穿烧坏；电器触头因温度太高而增添接触电 阻，接触电阻增添又加重发烧，如此恶性循环终究导致触头烧坏；同时温度太高还会影响电器保护机能的稳定性、动作的可靠性、计量的准确性。
The upper limit of the ambient temperature during the operation of electrical equipment designed and manufactured according to national standards should not exceed 40 ℃. However, for operating distribution boxes exposed to scorching sun in summer, due to direct sunlight, reflection of heat from cement floors, and heat generated by the equipment inside the box, sometimes the temperature inside the box exceeds 60 ℃. Such high temperatures can easily cause insulation aging of electrical coils and leads, leading to breakdown and burnout; Electrical contacts increase contact resistance due to high temperatures, which in turn exacerbates fever. This vicious cycle ultimately leads to contact burnout; At the same time, high temperatures can also affect the stability of electrical protection functions, the reliability of actions, and the accuracy of measurements.
2. Install lightning arresters only on the incoming side, and lightning protection cannot cover the entire equipment
Usually, fuses and other equipment are installed between the incoming and outgoing lines of distribution boxes and their busbars. When the outgoing lines are struck by lightning, if the incoming fuse is blown first, all distribution boxes will lose lightning protection. Every year, many distribution boxes are damaged due to lightning strikes.
3. Improper installation process may cause overheating and burning of the connection head
Some electricians do not compress the wire nose when changing the lead, and use multiple twisted wires to wind the wire nose and screw it together, resulting in the lead burning out shortly after the wire change. Some manufacturers produce distribution boxes with branch lines stacked and threaded on the bus, which have poor heat dissipation and a heavy load, naturally causing continuous faults.
4. The distribution box is put into use without inspection, leaving a hidden danger to safety
Although the products provided by equipment manufacturers have undergone strict inspections before leaving the factory, due to road bumps and loading and unloading vibrations, some connecting bolts may become loose after arriving at the site, resulting in overheating of some distribution boxes shortly after they are put into operation.
5. Improper installation of distribution boxes not only affects the appearance of the city, but also makes them susceptible to external damage. It is recommended to carefully consider selecting an appropriate installation location.
6. Some power supply systems that protect the neutral connection still adopt a three-phase four wire power supply method. The neutral line of the low-voltage power grid is long and has a high impedance. When the three-phase load is unbalanced, the neutral line will have zero sequence current passing through. At the same time, due to environmental degradation, wire aging, moisture and other factors, the leakage current of the wire passing through the neutral line also forms a closed circuit, causing the neutral line to have a certain potential, which is very unfavorable for safe operation.
7.配电箱间隔过小，电器间及相与相间的间隙小，有的还无显明的断开点，不但给电工操作带来了危险性，还将造成雨雾天气没法进行带电改换熔断器 等工作；配电箱普遍缺乏缺相保护，因缺相烧坏机电的事故时有发生；有的配电箱没有采用电子式电能表，没法实行远方集中抄表；有的配电箱常年关着，缺乏例行 检验保护。
7. The spacing between distribution boxes is too small, and the gaps between electrical appliances and phases are small, some of which do not have obvious disconnection points. This not only poses a danger to electricians during operation, but also makes it impossible to replace fuses with electricity during rainy and foggy weather; Distribution boxes generally lack phase loss protection, and accidents such as burning out mechanical and electrical components due to phase loss often occur; Some distribution boxes do not use electronic energy meters, making it impossible to implement remote centralized meter reading; Some distribution boxes are kept closed year-round and lack routine inspection and protection.
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