The fuse failure supervision function SEQSPVC is used to block the voltage-measuring functions when failure occurs in the secondary circuits between the voltage transformer (or combi sensor or voltage sensor) and protection relay to avoid misoperations of the voltage protection functions.
SEQSPVC has two algorithms, a negative sequence-based algorithm and a delta current and delta voltage algorithm.
A criterion based on the delta current and the delta voltage measurements can be activated to detect three-phase fuse failures which usually are more associated with the voltage transformer switching during station operations.