Application of Reliability Engineering in the Design and Development of a Motor Power System

The reliability issues of an electrical motor and its components are studied in this thesis, and a domestically manufactured 100 kW three-phase squirrel-cage induction motor is taken as an illustrative example. First, the failure mode and effect analysis (FMEA) of the induction motor is carried out. A fault tree analysis (FTA) is performed as well. Both are aimed to understand the potential failure causes of the induction motor. Afterwards, simulation based on the concept of extended stochastic petri nets (ESPN) is carried out to find the reliability of the motor system from knowing individual failure rates of its components. Finally, sensitivity study of individual components with respect to the system in terms of reliability is carried out. In numerical calculation, reliability prediction methods documented in the US MIL-HDBK-217F N2 and NSWC-11 are adopted for finding failure rates of the components and their mean times to failure (MTTFs). The result shows that life distribution of the studied motor system is best fitted by exponential distribution and the MTTF of the motor is 9.86 year. Based on both the criticality matrix constructed from FMEA and sensitivity analysis, it is identified that components bearing high risk are stator winding, bearings, and rotor winding in sequence.