Intelligent Fault Display Devices And Hybrid Dc Contactor

This paper presents two new electric system devices, a grounding and short-circuit fault indicator and an intelligent hybrid DC contactor. The fault indicator may be used in mid to high voltage power system. It has photo-electric isolation between high voltage and low voltage circuit, which significantly enhances the safety of the operator and the device itself. It also features low power consumption and low cost. And it is easy to install. In the other device, intelligent hybrid DC contactor, IGBT is creatively used to transfer current during breaking and closing, thus eliminating the arcing effect. The size of the mechanical part is tremendously reduced. As well lifespan and reliability are much improved.