Earth fault localization in isolated uninterruptible power supply (UPS) networks - a new approach

In this paper a new approach for earth fault localization in isolated uninterruptible power supply networks is presented and the fault location procedure is described in detail. This paper is focused on DC voltage systems. The detecting device is based on monitoring devices, which recognize the earth fault, a switching device for periodic grounding the faulty phase and a current measurement in each branch.It is based on well-known insulation monitoring systems and enables a quick and reliable location of the faulty branch in DC systems without switching consumers, as protection devices or other critical control devices off and on for earth fault localization. Additional experiences from substations are presented, where this system is already installed and in operation.