The first challenge is the dynamic changes that occur in the
total impedance presented by the SC and its protection
devices. The unknown state of the series capacitor, whether it
is in service, by-passed, or partly in service and partly by-
passed, complicates the reach settings of zone 1 elements. If
the capacitor is in service, over-reaching occurs and if the
capacitor is by-passed, under-reaching occurs depending on
the assumption made when setting zone elements.