Press

As the insulation layer of power cable is composed of various combustible substances, there is the possibility of explosion and fire. Once the cable is in fire, the fire will be fierce and spread rapidly. A large number of harmful gases will occur during combustion, making it difficult to put out the fire. Moreover, after burning out, it will take a long time to repair and cause serious losses. Therefore, great attention must be paid to preventing cable fire accidents, Therefore, the fireproof cable company reminds us to pay attention to the causes of fire and explosion.

(1) Short circuit fault caused by insulation damage. The protective lead sheath of power cable is damaged during laying or the cable insulation is mechanically damaged during operation, resulting in insulation breakdown between cable phases or between lead sheath, and the generated arc causes the insulation material and the outer protective layer material of the cable to burn and catch fire.

(2) The cable is overloaded for a long time. For long-term overload operation, the operating temperature of the cable insulation material exceeds the normal heating Z high allowable temperature, resulting in aging and drying of the cable insulation. This phenomenon of aging and drying of the insulation usually occurs on the whole cable line. Due to the aging and drying of the cable insulation, the insulation materials lose or reduce the insulation and mechanical properties, so it is easy to cause breakdown, fire and combustion, and even burn and fire at multiple places along the entire length of the cable.

(3) The oil immersed cable drips and leaks oil due to the height difference. When the height difference of oil immersed cable laying is large, the cable may drip oil. As a result of the flowing, the upper part of the cable is dried up due to the loss of oil, and the thermal resistance of this part of the cable increases, making the paper insulation coking and early breakdown. In addition, as the oil on the upper part flows downward, space is made at the upper cable head and negative pressure is generated, so that the cable is easy to absorb moisture and the end is affected by moisture. The accumulation of oil at the lower part of the cable produces a great static pressure, which makes the cable head leak oil. Cable dampness and oil leakage increase the probability of failure and fire.

(4) Insulation breakdown of intermediate joint box. The middle joint of the cable joint box is oxidized, heated and glue flowing during operation due to loose crimping, loose welding or improper selection of joint materials; When making the cable intermediate joint, the quality of the insulating agent poured into the intermediate joint box does not meet the requirements. When pouring the insulating agent, there are air holes in the box and the cable box leaks moisture due to poor sealing and damage. The above factors can cause insulation breakdown, short circuit and cable explosion.

(5) The cable head burns. As the surface of the cable head is affected by moisture and dirt, the porcelain sleeve of the cable head is broken and the distance between outgoing lines is too small, resulting in flashover and fire, causing the insulation on the surface of the cable head and the insulation combustion of the outgoing line.

(6) External fire source and heat source cause cable fire. For example, the spread of fire in the oil system, the explosion of oil circuit breaker, the spontaneous combustion of pulverized coal in the boiler pulverizing system or coal handling system, the baking of high-temperature steam pipes, the chemical corrosion of acid and alkali, welding sparks and other kindling can cause fire in the cable.