The insulating layer of the power cable is composed of […]
The insulating layer of the power cable is composed of various combustible materials such as paper, oil, hemp, rubber, plastic, and asphalt. Therefore, the cable has the possibility of fire. So what are the factors that cause the cable to catch fire? Trust is also the most concerned question for consumers. Next, the editor will introduce to us, hoping to help us in our days.
1. Incineration of cable head
Because the surface of the cable head is damp and polluted, the ceramic sleeve of the cable head cracks and the lead-out line is too small, causing flashover and fire, causing the surface insulation of the cable head and the lead-out line insulation to burn.
2. Damaged edges cause short circuit problems
Maintenance of power cables The lead sheet is damaged during laying or the cable insulation is mechanically damaged during operation, which leads to insulation breakdown between the cable phases or between the lead sheets. The occurrence of an arc causes the insulation materials and the outer maintenance layer materials 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 maximum allowable temperature of normal heating, and the insulation of the cable is aged and dried. This phenomenon of insulation aging and drying usually occurs on all cable lines. Because the cable insulation is aging and dry, the insulation material loses or reduces the insulation performance and mechanical performance, so it is easy to burn through fire, and even burn at multiple places along the entire length of the cable.
4. Boundary fire and heat sources cause cable fire
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 pulverized coal in the boiler pulverizing system or the coal conveying system, the baking of high-temperature steam pipes, the chemical corrosion of acid and alkali, electric welding sparks and other fires, all can cause the cable to occur Fire.
5. The immersion cable drips and leaks due to height difference
When the oil-immersed cable is laid with a large height difference, the cable may leak oil. As a result of the flow, the upper part of the cable is dried due to the loss of oil. The thermal resistance of some cables is added, which causes the paper insulation to burn and break down earlier. In addition, because the oil on the upper part flows downwards, there is space in the upper cable head and negative pressure is generated, which makes the cable easy to absorb moisture and make the end damp. The lower part of the cable is due to the accumulation of oil
A lot of static pressure is generated due to gathering, which promotes the oil leakage of the cable head. Moisture and oil leakage of the cable increase the probability of malfunction and fire.
6. Insulation breakdown of the junction box
The center joint of the cable joint box is not tightly crimped, welded, or the joint data is not properly selected, the joint is oxidized, heated, and glued during operation; when making the cable center joint, 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 pores in the box and the cable box is poorly sealed, damaged, and moisture leaks. The above elements can cause insulation breakdown, short circuit, and make the cable fire.