Patent ID: 7660088
Filing Date: 2010-02-09
Classification: H02H

Abstract:
1. An apparatus for compensating the sensitivity of a line current differential element of a first current differential relay providing differential protection for a transmission line of a power system during a single-phase pole-open condition, the apparatus comprising: a first delta filter configured to remove a first pre-fault current from a first fault current of the transmission line to form a compensated first current; a second delta filter configured to remove a second pre-fault current from a second fault current of the transmission line to form a compensated second current, each of a first phasor representative of the compensated first current and a second phasor representative of the compensated second current provided to the line current differential element to compensate the sensitivity of the line current differential element; and, a circuit for interrupting operation of the first line current differential element upon detecting the single-phase pole-open condition.