Short circuit fault caused by insulation damage
The protective lead of the power cable is damaged during laying or the cable insulation is mechanically damaged during operation, causing insulation breakdown between the cables or between the lead, and the resulting arc causes the insulating material and the outer protective layer material to ignite.
Cable overload operation for a long time
For a long period of overload operation, the operating temperature of the cable insulation material exceeds the maximum allowable temperature of normal heating, so that the insulation of the cable is aging and dry. This phenomenon of aging of the insulation usually occurs on the entire cable line. Due to the aging of the cable insulation, the insulation material loses or reduces the insulation performance and the mechanical properties, so that it is easy to be burned by fire, and even the combustion and fire occur simultaneously along the entire length of the cable.
Intermediate connector box insulation breakdown
The intermediate joint of the cable joint box is not tightly pressed, the welding is not strong, or the joint material is improperly selected. The joint is oxidized, heated and flowed during operation; when the intermediate joint of the cable is made, the quality of the insulating agent poured into the intermediate joint box does not match. It is required that when the insulating agent is poured, the air holes in the box and the cable box are poorly sealed and damaged, and the moisture leaks into the box. The above factors can cause insulation breakdown and short circuit, causing the cable to explode and ignite.
Cable head burning
Due to the moisture accumulation on the surface of the cable head, the cable sleeve of the cable head is broken and the distance between the lead wires is too small, causing flashover and ignition, causing insulation of the surface of the cable head and insulation of the lead wire.
External fire and heat sources cause cable fires
Such as oil system fire spread, oil circuit breaker explosion fire spread, boiler powder system or coal handling system coal power spontaneous combustion, high temperature steam pipe baking, acid and alkali chemical corrosion, welding sparks and other fires, can make cables A fire has occurred.