Because the insulation layer of wires and cables is composed of combustible substances such as paper, oil, hemp, rubber, plastic, asphalt, etc., there is a possibility of fire and explosion in the cables. So, what are the causes of fires and explosions in cables? Next, Zhengzhou Jinshui Industrial Co., Ltd. will introduce it to you, hoping it can help your life.
Due to moisture contamination on the surface of the cable head, the distance between the rupture of the porcelain sleeve of the cable head and the conductor is too small, causing a flashover fire, causing the insulation on the surface of the cable head and the insulation of the conductor to burn.
The protective lead sheet of wires and cables is damaged during the laying process or the cable insulation is mechanically damaged during operation, resulting in insulation breakdown between the cables or lead sheets. The resulting electrical isolation causes the insulation material and the cable outer protective layer material to burn and catch fire.
After long-term overload operation, the operating temperature of the cable insulation material exceeds the maximum allowable temperature for normal heating, causing the cable insulation to age and wither. This insulation aging and drying phenomenon usually occurs along the entire cable line. As the cable insulation ages and withers, the insulation material loses or reduces its insulation and mechanical properties, and it is easy to penetrate the fire and burn, or even burn simultaneously along the entire length of the cable.
Fire sources such as oil system fire spread, oil circuit breaker explosion fire spread, boiler powder manufacturing system or coal transportation system spontaneous combustion of pulverized coal, high-temperature steam pipe baking, acid-base chemical corrosion, welding sparks and other fire sources can cause cable fires.
When the oil-immersed cable is laid with a large height difference, oil dripping from the cable may occur. Therefore, due to the loss of oil, the upper part of the cable becomes withered, and the thermal resistance of this part of the cable increases, causing the paper insulation to coke and penetrate prematurely. In addition, due to the downward flow of oil, the upper cable head vacates space and generates negative pressure, making the cable easy to absorb moisture and causing the top to become damp. Due to the accumulation of oil, a large static pressure is generated in the lower part of the cable, which promotes oil leakage at the cable head. Cable moisture and oil leakage increase the likelihood of failure and fire.
Due to loose crimping, weak welding or improper selection of joint materials, the middle joint of the cable joint box is oxidized, heated and glued; when making the cable middle joint, the quality of the insulating agent filled in the middle joint box does not meet the regulations. When filling the insulating agent, there are air holes in the box, the cable box is poorly sealed, damaged, and moisture leaks into it.
The above-mentioned factors will cause the insulation to break through, form a short circuit, and cause the cable to explode and catch fire. Therefore, it is necessary to strictly follow the usage procedures for protection and operation during use.