The flammability and fire resistance of power cables are critical concerns, especially in power plants and large substations. In the event of a fire, these cables can significantly contribute to the spread of flames, endangering other circuits and causing extensive damage. Therefore, implementing effective fire protection technologies for power cables is essential to ensure the safe and stable operation of electrical systems.
Power cables play a vital role in electrical engineering by transmitting and distributing electrical energy. They consist of an insulated core, an insulating sheath, and a protective outer layer. These components are designed to withstand various challenging installation environments, offering excellent insulation, waterproofing, and mechanical strength. However, when an overcurrent occurs, leading to excessive heat, the cable's performance can degrade, increasing the risk of fire. This paper explores key fire protection strategies for power cables.
First, creating a favorable operating environment is crucial to prevent premature aging and damage to the cable's insulation. Cable trenches and tunnels must have proper drainage systems, such as water collection pits and drainage channels, to avoid water accumulation. Automatic pumping systems can be installed if necessary to maintain dry conditions. The slope of the trench should be maintained to prevent water, corrosive substances, or flammable materials from entering. Natural ventilation is recommended for tunnels, but if temperatures exceed 40–50°C due to high loads, a combination of natural and mechanical ventilation should be used. Ventilation fans should be linked with fire detectors to automatically shut off airflow during a fire. It’s important not to use the tunnel as an air inlet.
Cable fire doors should remain open whenever possible, and cables should be fully enclosed with fire barriers. Gaps in the trench covers should be sealed to prevent moisture and gases from entering. However, over-sealing can hinder inspection and heat dissipation, making it difficult to detect faults early.
According to statistics, about 70% of cable failures result from issues at the cable terminations. High-quality materials and precise manufacturing processes are essential to ensure that the lifespan of the termination matches that of the cable. The voltage rating and insulation level of the termination must meet or exceed those of the connected cable. Additionally, the insulation between the two sides of the termination should be at least twice the cable's protective layer insulation. The design of the joint must suit the environmental conditions and not restrict the cable's current-carrying capacity. Fireproof tape should be applied within 2–3 meters of the termination for added fire resistance.
Monitoring and managing cable terminations is a key aspect of fire prevention. Terminal heads should not be placed inside trenches or tunnels, while intermediate joints must be registered and tested regularly using various diagnostic tools. If abnormal temperature, odor, or smoke is detected, the cable should be removed immediately to prevent a potential fire.
A sufficient distance should be maintained between intermediate cable joints to avoid concentrated risks. If multiple joints are present, strict sealing measures must be taken to isolate them from adjacent cables.
Second, conducting regular preventive tests on cables is essential. After installation, a DC withstand voltage test should be performed to assess the cable's condition. Comparing the results with previous data helps identify trends and potential defects. If the leakage current increases rapidly with voltage or time, exceeds normal levels, shows a clear upward trend, or has a high imbalance between phases, it may indicate insulation issues that require further investigation. Adjustments to test voltage or duration can help determine if the cable is fit for continued operation.
Third, ensuring quality control during the production of cable heads is vital. Fourth, preventing external ignition sources from affecting cables is crucial. Equipment like oil-filled transformers, coal handling systems, and fuel engines can pose fire risks. Sealing cable trench covers near oil equipment prevents oil spills from igniting cables. Regular cleaning of coal dust around cables reduces the risk of spontaneous combustion. Cables near explosion-proof doors should be protected with fireproof enclosures to prevent damage from sudden pressure releases.
Finally, using sealing, blocking, and coating techniques can help prevent fires. While fireproof coatings offer good flame resistance and minimal impact on heat dissipation, they often suffer from poor quality, uneven application, and peeling. Solvent-based coatings, though common, have issues with toxicity, cost, and environmental impact. They also lack flexibility and durability, especially under bending stress. Therefore, it is more effective to use sealing and blocking methods rather than relying heavily on coatings. Ensuring that single cables do not ignite others is critical, so all cable entries into trenches, tunnels, trays, and jackets should be tightly sealed.
Description
-Contact Resistance:≤50mΩ
-Insulation Resistance:≥100mΩ
-Dielectric Strength:1,500V,
-1min Electronic Life:10,000 cycles
-Operating temperature:T120
-Rating current/voltage:6A 250V AC
Features
â—† Small Compact Size, high reliability
â—† Micro contact gap,High speed operation,High sensitirity,Micro operatizon travel.
â—† Long life & high reliability
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