Abstract:

Currently, the calculation and checking of conditions according to electric shock safety standards have not been used when designing precinct power networks in Vietnam's underground mines. In fact, the precinct power networks in the underground coal mine often has electrical equipment such as local fans, water pumps, hoists, tippers, chain conveyors, etc., which are driven by asynchronous motors. These motors are capable of generating back electromotive force applied to the network, which increases the risk of electric shock. Especially in the stages of testing, maintenance, and repair of equipment because at that time many motors work in under-load or no-load mode. In order to ensure safe conditions for people during installation, repair, and test operation, when designing the mine electrical network, it is necessary to add a calculation and check according to electric shock safety conditions. The methods of calculating and checking according to foreign electric shock safety standards are based on the results of experimental studies. Therefore, applying to Vietnam’s underground mines is often inappropriate because the working conditions are different. This paper proposes a general method, which can be applied to 380V, 660V, 1140V underground mine power networks and does not depend on experimental results, which are difficult to implement in Vietnam’s underground coal mine conditions.