Prediction Method of Residual Electrical Life of Air Circuit Breakers Based on Mechanical Parameters

Abstract

Air circuit breakers are critical protective devices in low-voltage distribution systems, and their reliability is considered to have significant influence on the operation of such systems. With respect to the electrical performance degradation of air circuit breakers, the relationship between the change in over-travel and the contact mass loss is analyzed, and a mechanical parameter method for the degree of contact erosion is proposed. The relationship between contact over-travel and the rotation angle of the pole shaft is investigated, and the monitoring of over-travel variation is achieved by measuring the pole shaft rotation angle. An electrical performance degradation model for air circuit breakers is established based on a univariate linear Wiener process with drift. The variation characteristics of the model parameters under different current stresses are analyzed, and a residual electrical life prediction method based on over-travel variation is developed. Electrical performance degradation experiments are conducted on air circuit breakers, from which the degradation model parameters are obtained. The residual electrical life is predicted using the over-travel variation data, and the relative prediction error is shown to be less than 5%. Real-time monitoring of the interrupting current and voltage waveforms of the air circuit breaker is not required by this method, which makes it convenient for practical engineering applications.