Safety barrier of electrical equipment for environments with a potential explosion in underground coal mines

Purpose. Electrical equipment for explosion-threatening environments in mines at risk of explosion communicates with the external environment through intrinsic safety barriers that limit the values of currents to values below the methane ignition, limit that exceeds the allowable concentration in the atmosphere. This avoids work accidents due to under-ground explosions, avoiding the risk of explosion through electric equipment. Methods. Experimental research has been based on the geomechanical characterization of the coal and surrounding rocks in the Jiu Valley Basin and measurements obtained in situ was researched by statistic methods. Three methods of studying barriers based on the use of the MATLAB program were used. The first method is based on MATLAB programming, the second involves the barrier study using the Simulink model and the third method is based on the use of the SimPowerSystems software package. In all three cases studied, the variation of the voltage at the output of the barrier and current through the barrier are analyzed considering two operating modes, the aperiodic and the oscillating regimes. Findings. The paper is a study of the intrinsic security barriers, based on which a correct dimensioning can be made. Originality. The originality of the paper consists in the analysis of the barriers with intrinsic safety, using the simulation with the MATLAB-Simulink program packages. Practical implications. All the methods addressed lead to obtaining the diagrams of variation of the voltage at the exit of the barrier and of the current through the barrier in two possible regimes: the aperiodic regime and the oscillating regime.