The insulation layer of the power cable is composed of various combustible materials such as paper, oil, hemp, rubber, plastic, asphalt, etc. Therefore, the cable has the possibility of catching fire. So what are the factors that caused the cable to catch fire?
1. Burning the cable head
Because the outer surface of the cable head is contaminated by moisture, the porcelain sleeve of the cable head is cracked and the spacing between the wires is too small, causing flashover to catch fire, resulting in the burning of the surface insulation of the cable head and the insulation of the wires.
2. Short circuit fault caused by edge damage
The maintenance of the power cable is damaged during laying or the cable insulation is mechanically damaged during operation, resulting in insulation breakdown between the cables or between the sheets. The resulting arc causes the insulation material and the outer maintenance layer of the cable to burn and ignite.
3. Long-term overload operation of the cable
Long-term overload operation, the operating temperature of the cable insulation material exceeds the allowable temperature of normal heating, so that the insulation of the cable is aging and drying. This kind of insulation aging and drying scene usually occurs on all cable lines. As the cable insulation ages and dries, the insulation material is lost or the insulation performance and mechanical properties are reduced. Therefore, it is easy to be burnt by fire or even burned at multiple locations along the entire length of the cable.
4. Boundary fire and heat sources cause cable fires
Such as the extension of the fire of the oil system, the extension of the fire of the oil circuit breaker, the spontaneous combustion of coal powder in the boiler pulverizing system or the coal conveying system, the baking of high temperature steam pipelines, the chemical corrosion of acids and alkalis, electric welding sparks and other fires can all cause the cable to fire Fire.
5. The immersed cable drips and leaks due to height difference
When the height difference of the oil-immersed cable laying is large, the cable may run into the oil scene. As a result of the flow, the upper part of the cable is dried due to the loss of oil. This is due to the addition of the thermal resistance of some cables, which causes the paper insulation to scorch and break down early. In addition, because the upper part of the oil flows down, it creates space at the upper cable head and generates negative pressure, which makes the cable easy to absorb moisture and make the end wet. Due to the accumulation of oil in the lower part of the cable
A large static pressure gathers to promote oil leakage at the cable head. Moisture and oil leakage of the cables have increased the probability of catching fire.
6. Insulation breakdown of the joint box
The center joint of the cable joint box is not tightly pressed, the welding is weak, or the joint data is not properly selected. During operation, the joint is oxidized, heated, and glued; when making the center joint of the cable, the quality of the insulating agent poured into the center joint box is not good. It meets the requirements. When the insulating agent is poured, there are air holes in the box and the sealing of the cable box is poor, damaged and leaking moisture. The above elements can cause insulation breakdown, constitute a short circuit, and cause the cable to catch fire.
The routine maintenance of wire and cable is the top priority. Fire, anti-theft and anti-rust. To cut the cable, please use our Silk Hardware Electric Scissors, AK-4700 special cut cable, suitable for any place to carry conveniently.