How can power cables be fireproof and explosion-proof?
In order to prevent cable fire accidents, the following preventive measures should be taken:
(1) select cables that meet the requirements of thermal stability. The selected cable can meet the heating requirements of long-term rated load under normal circumstances, and can meet the short-term thermal stability under short circuit conditions to avoid cable overheating and fire.
(2) prevent running overload. When the cable is running under load, it generally does not exceed the rated load. If the cable is running under overload, the overload running time of the cable should be strictly controlled to prevent the cable from catching fire due to overload heating.
(3) comply with the relevant provisions of cable laying. When laying cables, keep them away from heat sources as far as possible, and avoid parallel or cross arrangement with steam pipes. If they are parallel or cross, keep the specified distance and take heat insulation measures, it is forbidden that all cables are laid in parallel on the top or bottom of the hot pipes; In tunnels or ditches of some pipelines, cables are generally avoided. If necessary, insulation measures should be taken; Overhead cables, especially for plastic and rubber cables, there should be insulation measures to prevent thermal effects such as hot pipes; When laying cables, between cables, between cables and heat pipes and other pipelines, between cables and roads, railways, the parallel or cross distance between buildings and the like should meet the regulations; In addition, the cable application should have a waveform of remaining to prevent the cable from stopping running and shrinking in winter and causing excessive pulling force to damage the cable insulation. Cable turning should ensure the minimum radius of curvature to prevent excessive bending and damage to cable insulation; Cable tunnel should avoid joints, because cable joint is the weakest place in cable insulation, cable short circuit fault is easy to occur at the joint. When Intermediate head must be installed in the tunnel, fire-resistant partition plate shall be applied to separate it from other cables. The above cable laying regulations play an effective role in preventing cable overheating, insulation damage and fire.
(4) regular inspection. The power cable should be inspected regularly, and the air temperature and cable temperature in the cable trench should be measured regularly, especially the temperature of large-capacity power cable and cable connector box should be recorded. Find and deal with defects in time through inspection.
(5) tightly close cable holes, holes and set fire doors and partition walls. In order to prevent cable fire, all cable holes entering the control room, cable interlayer, control cabinet, instrument cabinet, switch cabinet, etc. through walls, floors, shafts and cable trenches must be tightly closed (tightly closed, smooth, beautiful, the cable is not damaged). Fire partition wall and fire-resist doors shall be set for long cable tunnels and their fork crossings. Under normal circumstances, the door on the cable trench or hole should be closed, so that once the cable is on fire, the burning range can be isolated or limited to prevent the fire from spreading.
(6) strip the outer jute outer protective layer of non-directly buried cable. Directly buried cables have a layer of jute protective layer such as asphalt immersion on the outside, which has a protective effect on cables in directly buried ground. When directly buried cables enter cable trench, tunnel and shaft, the jute protective layer such as asphalt immersion should be stripped to reduce the risk of fire expansion. At the same time, the cover plate on the cable trench should be covered, and the cover plate is complete, firm, and welding fire slag is not easy to fall in, reducing the possibility of cable fire.
(7) keep the cable tunnel clean and properly ventilated. The cable tunnel or channel should be kept clean, garbage and sundries should not be piled up, and the accumulated water and oil in the tunnel and ditch should be removed in time; Under the condition of normal operation, cable tunnels and channels shall be properly ventilated.
(8) keep the cable tunnel or channel with good lighting. The lighting in the cable layer, cable tunnel or channel is always in good condition, and special ladders are provided for the tunnels and Channel ports that need to go up and down, so as to facilitate operation inspection and cable fire fighting.
(9) prevent the fire from entering the cable trench. When carrying out hot work near the cable, measures should be taken to prevent the fire from entering the ditch.
(10) regular maintenance and testing. According to the regulations and the actual situation of cable operation, the cable should be regularly overhauled and tested in order to deal with defects and find potential faults in time, ensure the safe operation of the cable and avoid the occurrence of cable fire. When entering the cable tunnel or channel for overhaul and testing, the relevant provisions of regulations on safety work in electric power industry shall be observed.