MATHEMATICAL MODEL OF MINE SECTION POWER NETWORK IN CASE OF CURRENT LEAKAGE ON THE GROUND THROUGH HUMAN BODY RESISTANCE

Rising of the supply voltage level for mine section power network to 3.3 kV requires improvement of the automatic device for workers protection against electrical shock. Known dependences for state estimation of current leakage circuit through human body resistance ignore several factors, importance of which increases with supply voltage level rising, that does not allow using them to 3.3 kV networks. In this work the mathematical model of coal mine section power network was improved by taking into account: decreasing of frequency of induction motor back electromotive force after network supply voltage safety tripping; changing of resistance and capacitance of cable system insulation, which defining value of current leakage, when switching units of branches are tripping; dependence of inductance of self-balancing compensator for capacitive component of leakage current on total capacity of three phases insulation towards the ground. The mathematical model is presented as matrix differential equation, which was formed by using matrix-topological analysis method of electrical circuits. The results can be used during the design of new and improvement of existing protection devices against leakage current on the ground in the section network.