Shielding properties analysis of underground methane sensor based on finite element simulation and electromagnetic measurement

In order to clear up false alarms, issued by underground methane sensors, caused by Electromagnetic Interference (EMI), a novel field way was brought forward in which the simulation and radiated emission measurement were adopted to accomplish the analysis of shielding property about methane sensor. The data was acquired through the R&S spectrum analyzer FSP7. With analyzing the influence of cable aperture on enclosure shielding properties through simulation and measurement, the optimization of explosion-proof enclosure was finished according to the distribution of radiated interference characteristics and simulation of the trumpet structure shield performance. As a result, with the optimization of explosion-proof enclosure, the false alarms of methane sensor significantly reduced; however, there were still occasionally false alarms when nearby electrical equipments were switched on and off. Therefore the complex EMI filter was put forward at power ports and the EMI was controlled within the allowable range. The running results demonstrated that the problem of false alarms had been resolved successfully. It is concluded that the improved shielding and filtering are highly significant in enhancing the Electromagnetic Compatibility (EMC) of the methane sensor.