Improving the reliability of electrical drives through failure prognosis

Fault diagnosis and its extension to failure prognosis aim to develop methods that will decrease the unanticipated outages and thus employ techniques to increase reliability. Among these are redundancies and change of topology, power levels and control algorithms. We show that since diagnosis methods are imperfect, false positive and false negatives as well as delayed fault diagnosis are possible and they will lead to decreased life. On the other hand, failure prognosis, especially in slowly evolving faults will lead to more accurate estimates, in-time remediation, and increased reliability. We give an example of an intermittent open circuit in one of the phases of an AC permanent magnet motor to illustrate the concept.