<p>There is provided an apparatus for producing a trip signal to activate a circuit breaker in an alternating current power line, said apparatus comprising: a sensing circuit operable to sense values representing: a phase difference between current and voltage in said power line; and current amplitude in said power line; a comparison circuit operable to compare said sensed values of phase difference and current amplitude with a trip characteristic defining fault conditions and non-fault conditions and to generate a fault indication signal when a fault condition arises; a fault discriminator operable in response to said fault indication signal to generate a fault-identifying signal discriminating between: a first class of fault in which a mean current value after said fault indication increases relative to a mean current value before said fault indication; and a second class of fault in which a mean current value after said fault indication does not increase relative to a mean current value before said fault indication; and a trip signal generator responsive to said fault-identifying signal and operable to generate said trip signal.</p>
申请公布号
WO2004045036(A1)
申请公布日期
2004.05.27
申请号
WO2003GB04199
申请日期
2003.09.30
申请人
FRDX LIMITED;SCOTT, GORDON, BRYON;STONE, RODNEY, A.