Research on discharge spark safety of equivalent receiving antenna of underground metal structure

The metal structures distributed in underground coal mine roadways can be equivalent to the receiving antenna to absorb electromagnetic wave energy and release the energy in the form of discharge sparks under specific conditions. The accumulated energy has the risk of igniting explosive gas. In order to solve the problem, the conditions of ignition of gas by discharge spark when the metal structure is equivalent to the receiving antenna are analyzed, and the calculation expression of the maximum power that can be absorbed by the discharge spark as load is derived. It is concluded that when the gas volume fraction is 8.5% and the metal structure is equivalent to the receiving antenna, the maximum allowable power that the discharge spark will not ignite the gas is 2.8 W. Wireless Insite electromagnetic simulation software is used to simulate the maximum power that can be absorbed by the discharge spark as load under different working conditions of the radio frequency equipment. The results show that the greater the output power of radio frequency equipment, the lower the working frequency of radio frequency equipment, the closer the metal structure to radio frequency equipment, the greater the load maximum power that can be absorbed, the greater the potential safety hazard of gas ignited by discharge spark. When the minimum safety distance between the transmitting antenna of the radio frequency equipment and the metal structure is 0.1 m, the discharge sparks generated by the radio frequency electromagnetic radiation energy in the frequency band below 800 MHz of the radio frequency equipment have the possibility of igniting gas. The discharge sparks generated by the radio frequency electromagnetic radiation energy in the frequency band above 890 MHz of the radio frequency equipment in the metal structure are intrinsically safe and will not ignite gas.