Tóm tắt:

•The power supply netvvorks at the underground mines containing semiconductor írequencỵ converters (combined netvvorks) are being used extensively in Quảng Ninh area. In order to be abìe to select effective solutions to limit thê leakage current irvthese networks, it is necessary to know the characteristics of . the léakage currents generated in them. The paper presếhts results of calculating thè leakage cụrrents in combined networks when there is leakage in the AC netvvork section, leakage in the DC section and leakage in the variable írequency network section, Research results show that when a portion of the DC netvrork has the asymmetric insulating resistancé or the variable frequency AC network part has considerable length, to ensure the safety, the oíher leakage current limiting solutions should be applied.