The larger current that the wire can bear is not obtained by calculation, but by experiment. The test method is to test the wire with a length of 1m under pressure in the environment of 20°C, so as to obtain the safe current value through which the wire with a length can pass continuously. This value will be marked on the nameplate of the product-each brand and each type of wire only needs to be tested once.
However, in practice, this current will definitely change. First of all, let’s talk about the factors that affect the use force of wires.
1. temperature.
The higher the temperature, the lower the current carrying capacity of the wire. This is a common problem, and it is also the main reason why building cables are thicker than patch cables. In addition, in many cases, the ambient temperature is uncontrollable, and ventilation effect, sunlight, cable density, etc. will all affect the ambient temperature, thus affecting the current-carrying capacity of the cable.
2. Cable density.
Cable laying is too dense and too dense, which will not only cause excessive temperature. If multiple wires are used, the adjacent effect and skin collection effect will be formed, so that the charge will be concentrated in the local part of the cross section of the wires, thus reducing the load flow of the wires.
3. Length.
The longer the cable, the lower the current carrying capacity. The current carrying capacity of 100m cable is different from that of 10000m cable, and there is little difference.
During shelf storage and transportation, wires and cables should pay attention to the following points:
First, when storing, first of all, contact with acidic, alkaline and corrosive substances should be prohibited and stored separately. Thermal insulation wires and cables should be stored in a dry and ventilated warehouse. The proper temperature in the warehouse is 5-30 degrees and the relative humidity should not exceed 75%. In order to avoid direct sunlight and premature aging of the insulation layer, the glass on the sunshine window of the warehouse should be painted with white paint.
Second, there should be no harmful gas in wires and cables, which can destroy insulation or corrode conductor metal.
Third, avoid storing in the open air to prevent accidental damage.
Fourth, small quantities of wires and cables can be palletized in the shelves, with the palletizing height of 5-10 volumes, and the palletizing height of large quantities of cables, batteries, power supplies, batteries and electricity. Generally, when storing, you should always check whether it is beautiful.
V. The storage time of wires and cables shall be subject to the factory date of the products. Under normal circumstances, the storage time shall not exceed one and a half years, and the longer period shall not exceed two years. During storage, we should always pay attention to the changes of temperature and humidity. If the storage temperature exceeds 30 degrees, the cooling measures should be taken immediately. If the relative humidity reaches 75% for three consecutive days, desiccant or other methods should be used to absorb moisture and humidity.
Hainan wire & cable