Reliability Evaluaton Of Low-Voltage Switchgear Based On FFTA

In this paper,the reliability characteristics of low-voltage switchgear were proposed that are reliability,mean time between failure,average failure rate,meantime to repair,the common reliability analysis methods were introduced,the fault tree of MCC switchgear was built up and MCC switchgear was implemented with elementary fault tree analysis.Due to failure probability of element inaccuracy,fuzzy set concept of engine ering fuzzy mathematic was introduced such as cut set,membership function,triangle-shape fuzzy number and trapezoid fuzzy number.And fuzzy fault tree was built up,basic event fuzzy probability transform to triangle-shape fuzzy number or trapezoid fuzzy number was studied.Six loops of MCC switchgear were implemented with fuzzy fault tree analysis(FFTA): absorber A and B circuit,lye circulation return circuit,water pump circuit,electrolysis room fan electrical circuit,switch board room fan electrical circuit.The least cut set of each loop and top event fuzzy failure probability basic on triangle-shape fuzzy number basic event were computed.Meanwhile water pump circuit was took for example,basic event fuzzy important of water pump circuit number was analyzed with trapezoid fuzzy,Comparing with traditional FTA,the result of fuzzy probability fault tree was acceptable in engineering.The principles of low-voltage switchgear fault tree analysis(FTA)software which was designed with VC++ computer language was described,the reliability qualitative analysis and quantitative calculation such as probability important and key important were implemented;the transfer-event was applied to solve the drawing of large -scale fault tree.