Causes of fires caused by power cables
1. The power cable catches fire due to external fire, and the poor underground conditions in the coal mine cause the electrical equipment to be easily damaged, causing the electrical equipment itself to burn, thereby igniting the power cable
connected to the electrical equipment or the power cables laid around it, causing a fire.
2. Overcurrent of the power cable leads to heating and ignition of the power cable. Rubber-sheathed power cables
and protective covers Power cables are vulnerable to damage from rocks, coal mining machinery and tools due to their lack of reliable protection against mechanical damage, which causes moisture and dust to penetrate into the power cables, which in turn cause short circuits and fires; power cable insulator machinery in use The damage can cause insulation breakdown between the phase wires of the power cable or between the phase wires and the steel armor, resulting in arcing, causing the power cable insulation and the power cable jacket to catch fire. Overloading the power cable for a long time will cause the insulation performance to decline or even lose, causing the power cable insulation to break down and catch fire; when the equipment failure causes the current to suddenly increase, the electromagnetic starter and feed switch do not work, resulting in a sharp rise in the temperature of the power cable. Causes insulation breakdown and fire.
3. The connection failure of the power cable
leads to an increase in the resistance of the joint, causing local high temperature (arc) ignition. The power cable connector is the weakest link in the circuit. If the connection between the core wire of the power cable and the terminal of the electrical equipment is unreliable, due to the small contact area, the terminal and the power cable joint are very prone to arcing and fire. The underground air humidity is generally above 95 points, and the power cable junction box is prone to moisture. If the junction box is poorly sealed, moisture can penetrate, which can cause insulation breakdown, resulting in short circuits and fires.
4. Power cable aging, performance degradation such as insulation, withstand voltage, overcurrent capability, etc. Power cable
insulation aging causes fire. The essence of power cable insulation aging is an irreversible change in material properties. One is that the insulation layer of the power cable is aging normally during use. If it is not replaced in time, it is easy to cause a fire; the other is that in abnormal use, the power cable is overloaded or damaged by external forces. Power cable short circuit fire.
5. Use non-flame retardant power cable
s to delay the local ignition point and cause fire. Non-flame retardant power cables are composed of ordinary PVC. When a power cable
is ignited, a large amount of combustion heat is generated. After the external fire source is removed, the calorific value released by it is greater than the sum of the preheating and heat dissipation required for combustion, and the combustion tends to be vigorous. Therefore, once a non-flame retardant power cable is ignited, even a small spark can spread the fire quickly, causing a fire. Coal mines are flammable and explosive places. The use of non-flame retardant power cables in coal mines will undoubtedly plant a time bomb for coal mine safety.