Surge Characteristics Induced in the Secondary Circuits by a Lightning Impulse Current Injected into the Grounding Grid: An Experimental Study

In substations, the failure of secondary circuits due to lightning surges is a significant concern with respect to surge disturbances. When a lightning surge enters a substation from the transmission-line side, it is divided between the primary circuits and the grounding grid through the action of lightning arresters. This division may result in varying trends in the induced surge characteristics within the secondary circuits, influenced by the distinct paths and the sensitivity to certain geometric parameters of the primary/secondary circuits. Consequently, characterizing them individually is crucial. Using a test platform for the primary/secondary circuits of gas-insulated substations, this study conducts an experimental study on the surge characteristics induced in vulnerable circuits when a lightning impulse current is injected into the grounding structure. An emphasis is placed on the effects of cable length and its position on the induced surge characteristics by utilizing the routes of a control cable as a parameter.