Storage PoF model of electromagnetic relays based on electrical contact theory

To predict the storage life (SL) of electromagnetic relays better, effectively guide life extension project and save maintenance costs, this paper proposes a Physics of Failure (PoF) model for assessing the SL based on Holm electrical contact theory. Firstly, considering the relationship between storage environment, processing technology, material and contact resistance, the shrinkage, interface and body resistance expressions are constructed. Then the PoF model is established regarding contact resistance to the initial value ratio as an input parameter. The dimensionless parameter in the model that reflects the diffusion rate of the corrosion film on contact surface is determined from the contact resistance data measured in the Accelerated Storage Degradation Test (ASDT). By using this model to calculate SL of the samples at different stress levels and comparing results with ASDT records, the accuracy of the model is verified. It proves that the proposed storage PoF model can predict the SL of electromagnetic relays effectively and provides a theoretical reference for rapid assessment of their storage state.