Failure Analysis Informing Embedded Health Monitoring of Electromagnetic Relays

In this paper, failure analysis of an electromagnetic relay is studied to inform embedded health monitoring for the prediction of Remaining Useful Life (RUL) of electromagnetic relays. A statistical design of experiment with online monitoring of voltage, current, temperature, resistance, duty cycle, and frequency is used to identify relay failure precursors. Examples of detected precursors include abnormal spikes in resistance and extension of the average closing time of the relay within the final 1.5 million actuations prior to failure. A detailed post-failure analysis utilising white light interferometry and energy dispersive X-ray (EDX) analysis reveals the relay failure modes associated with erosion, pit and crater formation, and material transfer. The results demonstrate that low resolution data can detect signatures of impending failure modes such as stuck open and closed failures as well as unacceptable long opening times. The findings within this paper demonstrate remote monitoring of the near real-time health of electromagnetic relays with low resolution data analysis.