Prediction ofCircuit-Breaker Performance Basedona RefinedCybernetic Model

An improved empirical modelforcircuit-breaker arcsis presented. Themodelmakesitpossible topredict thebreaker thermal short-circuit interruption performance within theentire range ofprac- tical interest, using only asmallnumberofmeasurements fromsyn- thetic tests ofaproduction SF6breaker. Theprocedure isbasedonthe cybernetic modeldeveloped byHochrainer etal.Thekeyimprovement isthat theresponse timecharacteristic isexpressed asafunction ofthe dynamic conductance andnotoftheexternally imposed current. The numerical methodconsists ofaniterative process forfitting thechar- acteristic functions tothemeasured databymeansoftruncated Che- byshev series, anddoesnotrequire manualintervention. Thisproce- durehasasignificant advantage overmostprevious treatments inthat itdoesnotrequire anysmoothing ofthemeasured data, andhasproved tobeinsensitive against noise.