Effect of inrush current flowing into EMI filter on the operation of ICT equipment in HVDC system

We describe how inrush current flowing into an electromagnetic interference (EMI) filter when ICT equipment is connected to an HVDC system affects the operation of other currently connected ICT equipment. When ICT equipment is connected to an HVDC system, inrush current flows to the EMI filter of newly connected ICT equipment. The inrush current causes voltage oscillation at the input of other (previously connected) equipment. If the input voltage of other equipment deviates from the normal DC voltage range specified by ITU-T L.1200, the ICT equipment may stop operating. This paper addresses the relationship between the capacitance of the EMI filter capacitor and the voltage oscillation at the input of the ICT equipment. We clarified that if the capacitance is less than 13 μF, the input voltage of ICT equipment does not deviate from the normal DC voltage range when inrush current flows.