Research of Key Technologies about Electrical Safety of Coal Mine

The paper analyzed fire sources of domestic gas explosion accidents from 2005 to 2009 and got a conclusion that gas explosion accidents were mostly caused by electrical fire source, which accounted for 48.1%. It analyzed safety performances of mine-used electrical devices and proposed operation places and safety requirements of each type of electrical devices. Firstly, systems and devices with weak current for coal mine monitoring, communication, control and signals should primarily be intrinsically safe and signals transmitting between the devices must be intrinsically safe. Secondly, electrical devices with large power should be flameproof type devices and wiring cavity of the devices should be separated from main cavity. Thirdly, special cap-lamp cannot be operated on or off when gas concentration achieves explosion concentration value. Fourthly, explosion-proof electrical devices should be used in non-explosion places such as underground shaft station of mine with low gas concentration. Fifthly, trolley locomotive and normal mine-used electrical devices cannot be used in mine with coal and gas outburst. Sixthly, time-delay measures should be used in under-voltage and no-voltage protection of underground electrical devices so as to decrease cutting off times of local ventilator. Seventhly, immersible pumps with large power should be used for underground draining devices. Eighthly, switches should be set at air-intake places of total wind pressure, otherwise methane sensors should be set with functions of power-off and interlocking when methane is over limit. The paper provides some guidance to improve electrical safety performance of coal mine and avoid or decrease accidents of gas explosion and mine submerging.