Preventive measures for external fire sources of
power cables
Standardize underground operations to prevent irregular operations that may cause electrical equipment to catch fire; establish and improve fire monitoring and early warning systems.
Overcurrent power cable precautions. Reasonable use of overcurrent and leakage protection devices can act in time to cut off the source of faults and prevent accidents when overcurrent, short circuit or leakage occurs in the power cable. According to the actual situation of the mine, correctly calculate and set the setting value of the overcurrent protection device, maintain it regularly, and install the leakage protection device reasonably according to the actual distributed capacitance of the underground power grid, which can prevent the phase-to-phase short-circuit fault caused by the leakage of the power cable. Pay attention to the influence of
power cable laying and installation quality and laying environment, and the power cable support and hoisting should be reasonable to avoid damage to the power cable sheath and insulation. Overuse.
Power cable joint failure prevention measures. The
power cable must be connected to the electrical equipment using a junction box that matches the performance of the electrical equipment. The core of the power cable must be connected to the electrical equipment with a toothed pressure plate (claw) or a wire lug. The enclosure protection level of the
power cable junction box must meet the requirements of long-term adaptation to underground humid and dusty environments.
Anti-aging measures for power cables, establish a strict management mechanism for power cable aging, and regularly conduct power cable insulation withstand voltage tests; for
power cables with aging insulation layers, it is first necessary to recalculate whether the selection of cross-sectional area is reasonable; it is necessary to check whether the power cable model is Match with the application environment; it is necessary to replace and repair in time.
The use of non-flame retardant power cables is strictly prohibited. When using power cables in coal mines, you must use flame retardant
power cables with coal mine product safety signs. Coal mines are strictly prohibited from using non-flame retardant power cables.
Follow the rules and use flame retardant
power cables. Flame retardant
power cable refers to the power cable in which the sample is ignited under the specified test conditions. After the test fire source is removed, the flame spread is only in a limited range, and the residual flame or residual combustion can be extinguished by itself within a limited time. According to the definition of flame retardant power cable, "flame retardant power cable" is not "non-combustible
power cable". Even if coal mines use flame retardant power cables, flame retardant power cables can burn if other appliances are not adequately protected or if there is an external fire source.
Scientific design and standardized procurement. The design of the whole system should start from the whole. According to the load of the power supply line and the requirements of the place of use, in addition to the flame retardant
power cable with suitable specifications and cross-sectional area, it is also necessary to select the load and electrical protection device with suitable capacity. The circuit where the electrical equipment is located should have overcurrent and leakage protection devices to prevent accidents.
Reasonable use and regular maintenance. In the limited underground space and harsh environment, when laying power cables and installing other electrical equipment, space factors need to be considered to ensure that the electrical equipment has a good heat dissipation channel to prevent the electrical equipment from burning out the
power cable due to untimely heat dissipation.
