Improving the accuracy of estimation of reliability parameters of low-voltage switching devices installed in the systems of in house power supply taking into account the main influencing factors

Relevance. The article investigates the issues of evaluating the reliability parameters of contacts of low-voltage switching devices (LWSD) installed in low-voltage electrical networks of power supply systems of industrial enterprises. Object. To investigate the main parameters of reliability of LWSD contacts using the statistical method and to analyze the physical processes in the contact connections. Methods. To improve the accuracy of determining the LWSD failure rate, it is proposed to introduce correction factors that take into account the influence of the main influencing factors on the studied LWSD. The study of the switching life of contacts was performed by analytical and graphical-analytical methods. Results. On the basis of the conducted researches it has been established that the graphical-analytical method with taking into account correction factors can be recommended to increase the reliability of LWSD parameters estimation. The value of the number of switching cycles of the device, after which the occurrence of failure is most likely, depends on its loading factor. It is revealed that for the studied devices after expiration of 25% of the resource number of switching cycles the probability of failure-free operation becomes lower than the permissible value. Conclusions . The research results show that after 3-5 years of operation the probability of failure-free operation of the observed LWSD decreased to the value less than 0.85. The obtained results are recommended to be taken into account when drawing up schedules of preventive maintenance in the electrical networks of inhouse power supply.