Failure Rate Evaluation of Sensitive Equipment Caused by Voltage Sag

Abstract

In order to accurately evaluate sensitive equipment failure rate caused by voltage sag, the concept of credibility measure is introduced to measure the uncertainty of equipment failure event. This evaluation measure can avoid the deficiencies containing in classical probability measure which needs a large number of testing samples. The uncertainty of failure event is presented by a fuzzy measure where the membership function of equipment voltage tolerance curve corresponding to the characteristic quantities in the uncertain area was determined by fuzzy statistical and a polynomial fit method. Then the credibility distribution function was determined. The proposed evaluation model of sensitive equipment failure rate caused by voltage sag is developed. Using the practical testing samples, the personal computer (PC) was evaluated by the proposed method. Comparing the proposed method with current methods, the results have shown that the proposed method is proper, correct and credible. This method may be more practicable in practical condition.