| Title |
Switching Surge Simulation of VCB for Reactor Coolant Pump Motor and Coping with Motor Trip by Surge Arrester Failure |
| Authors |
토마스 쥬마 칼렌가(Thomas Tsuma Kalenga) ; 장중구(Choong-koo Chang) |
| DOI |
https://doi.org/10.5370/KIEE.2021.70.2.297 |
| Keywords |
Medium voltage motor; Ground fault relay; Surge arrester; VCB switching surges; and Surge simulation |
| Abstract |
Several failures of the surge arresters in nuclear plants during normal power operation caused ground fault relay (GFR) to trip and shut down the reactor coolant pump (RCP). Furthermore, several false trips of the GFR were reported between 2004 and 2018. This was assumed to have been caused by vacuum circuit breaker (VCB) switching surges. This paper sought to establish the expected switching surges in this network, how safe it is to operate the reactor coolant pump motor (RCPM) without a surge arrester (SA), establish the cause of the false operation of the ground fault relay, and ways to mitigate against it. It turns out that the VCB switching surges are within the RCPM insulation rating. The GFR activation was not caused by the residual current I0 created by the VCB switching surges. The SA should be removed from the circuit until a SA monitoring scheme is put in place. |