Subway power cable gj

Voltage level requirements for subway power cables: The traction system is mostly powered by DC voltage, with voltage levels of 3000V, 1500V, 750V, etc.

Flame retardant requirements: Chongqing Rail Transit Line 2 is one of the earlier rail transit projects to use mineral cables. In Line 2 and three underground stations, all electrical circuits for major fire protection loads, including tunnel fans, jet fan system power supply, gas fire protection, emergency evacuation lighting, and indicator power supply, use mineral cables.

1) In the construction of rail transit, the flame retardant performance of cables is one of the main performance indicators for selecting cables for station equipment. The performance of the selected cables varies greatly, which can reveal their significant differences in fire conditions.

2) Due to the concentration of pedestrian flow and high density of personnel areas in rail transit stations, the evacuation of personnel in the event of a fire is crucial in the initial design stage. However, the "secondary disasters" caused by fire accidents are more dangerous and result in greater loss of life and property than the fire itself. The casualties of fire accidents are mostly due to suffocation caused by toxic gas and smoke.

3) Mineral insulated cables are divided into two types: heavy-duty cables (1000 volt class) and light-duty cables (600 volt class). The number of cable cores includes 1, 2, 3, 4, 7, 12, 19 cores, and can reach up to 24 cores. 1-4 cores are mainly used for power and lighting, while 7 or more cores are mainly used for control and communication. Compared with cables of the same cross-sectional area, magnesium oxide cables can increase their current carrying capacity by more than one cross-sectional level. At the same time, it can withstand considerable overload, with an overload capacity of over 100 times the normal current carrying capacity.

4) Mineral cables are composed of electrical copper, magnesium oxide insulation materials, and metal sheaths, with outstanding performance. The long-term use temperature of this cable is 250 ℃, and it can continue to supply power for more than 3 hours even in a fire environment of 950 ℃ to 1000 ℃.

5) In the event of a fire, even if it burns in a flame at the melting point of copper (1083 ℃), it will not produce any smoke, halogens, or toxic gases, and will not disintegrate due to melting or combustion in most places, nor will it spread the flame. Therefore, the power supply lines for emergency lighting and evacuation instructions have been able to provide conditions and time for personnel evacuation and firefighting work within the station.