Fire prevention technology of the hottest power ca

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Fire prevention technology of power cables

according to incomplete statistics, there have been more than 100 major accidents caused by the spread of cable fires in the country in the past decade, with a total of more than 320000 meters of cables burned, and the cost of restoration and reconstruction is high It takes a long time, and the loss of less power supply alone is more than 10 billion yuan. The cable fire accident also has its special harm, that is, the failure of the control circuit causes the expansion of the accident, and even damages the main equipment. Moreover, it is difficult to repair and cannot resume production for a long time

power cables are power plants Substation is an important part of maintaining normal operation. The cable is in the power plant Wide distribution in substation Flammability of cables String ductility of cable fire The severity of the consequences of cable fire, so that the cable fire prevention work has been affected by the power sector Fire protection institutions and scientific research institutions attach great importance to it. In view of the frequent occurrence of cable fire accidents, it is necessary to discuss the fire safety measures of cables again

create a good operating environment to avoid accelerated aging and damage of cable insulation

cable trench Cable tunnels should have good drainage facilities, such as shallow drainage ditches The water collecting well can effectively flow, and it can be automatically started when necessary Stop the pumping device to prevent ponding and keep the interior dry. Cable trench The longitudinal drainage gradient of the tunnel should not be less than 1% ~ 2%, and should be at least greater than 0.5% to prevent water Corrosive gas or liquid and flammable liquid or gas enter. Cable trench Cable tunnel. The cable tunnel should be naturally ventilated, but when the normal load of the cable makes the air temperature in the tunnel higher than 40 ℃ ~ 50 ℃, the combination of natural ventilation and mechanical ventilation can be adopted for ventilation. The fan of the ventilation system shall be interlocked with the fire detector to ensure that the air supply can be automatically stopped in case of fire in the tunnel. The cable tunnel shall not be used as the air inlet of the ventilation system

it should be avoided to keep the cable fire door in a normally closed state Completely seal the cable with fireproof partition Filling and sealing the gap of the cable trench cover plate will affect the ventilation and heat dissipation of the cable. Moreover, completely sealing the cable also makes it impossible to inspect the cable normally, and cable faults cannot be found in time

in addition, we should improve the rat prevention measures that the state attaches great importance to the development of new material industry Facilities where snakes enter to prevent small animals from damaging cable insulation and causing accidents

strengthen the preventive test of cables

the preventive test of cables should not only see whether the test data are qualified or not, but also whether the elongation is large or small. The data should be compared and analyzed. It can not only be compared with the test data of the same cable, but also with the historical test data of this cable to explore the law of the test data. For example, during the DC withstand voltage test, if the measured leakage current value drives the development of these energy-saving and environmental protection building materials and related manufacturing technology with the increase of the test voltage value or the increase of the pressurization time, or the value increases more compared with the same cable, or there is an obvious upward trend compared with the previous measured data of this cable, or the leakage current imbalance coefficient between the three is large, it should be carefully analyzed. If it is not caused by improper test methods, the test voltage can be appropriately increased or the test time can be extended to judge whether the cable meets the conditions for continuous operation

strengthen the management and operation monitoring of the production quality of cable head

according to statistics, cable fire caused by cable head failure Explosion accidents account for about 70% of the total cable accidents. Therefore, we must strictly control the manufacturing materials and process quality of cable head. It is required that the service life of the cable head made shall not be less than that of the cable. The rated voltage level and insulation level of the joint shall not be lower than the rated voltage level and insulation level of the connected cable. The withstand voltage value between the insulating pads on both sides of the insulating head shall not be less than 2 times the insulation level of the cable sheath. The joint form shall be suitable for the set environmental conditions and will not affect the flow capacity of the cable. Within the range of 2 ~ 3 meters on both sides of the cable head, fire-proof wrapping tape shall be used for fire prevention and burning extension treatment

generally speaking, cable head is the weak link of cable insulation, so strengthening the monitoring and management of cable head is an important link of cable fire prevention. The terminal cable head must not be placed in the cable trench Cable tunnel Cable tray box In the cable interlayer. It is placed in the cable trench Cable tunnel Cable tray box The intermediate cable head in the cable interlayer must be registered and monitored with a variety of monitoring equipment. Abnormal temperature rise or smell is found at the cable head In case of smoke, exit the operation as soon as possible to prevent the cable head from catching fire during operation

sufficient safe length distance should be ensured between each intermediate cable head. 2. According to the requirements of the above measured parameters, more than two cable heads should not be placed in the same position, and strict blocking measures should be taken between the cable head and other cables

prevent other equipment from catching fire and ignite cables

oil filled electrical equipment and coal handling equipment can ignite cables Pulverizing system Steam oil system. Corresponding measures must be taken against them; The cover plate of the cable trench near the oil filled electrical equipment shall be sealed to prevent the oil from flowing into the cable trench to ignite the cable in case of equipment failure and fire. Coal handling The accumulated powder on the electric cable near the pulverizing system should be cleaned regularly to prevent the pulverized coal from self igniting and igniting the cable. The cables facing the explosion-proof door of the pulverizing system shall be packed in fire-proof trough boxes to prevent the action of the fire-proof door from spitting fire and igniting the cables. The cables under the turbine head shall be packed in fireproof trough boxes

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