Analysis of Electromagnetic Transients in Secondary Circuits due to Disconnector Switching in 400 kV Air-Insulated Substation

The paper describes the electromagnetic transients caused by disconnector switching in 400 kV air- insulated substation. Transient overvoltages in the secondary circuits of capacitor voltage transformer (CVT) were calculated using the EMTP- ATP software. The transfer of electromagnetic transients through substation’s grounding grid was analysed in order to determine the overvoltages at the terminals of protective relays located in control (relay) room. The overvoltages in secondary circuits, caused by disconnector switchings, were recorded during the on-site testing.