Intelligence Technology And Reliability Analysis Of Electronic Over-Load Protective Relay

Since twenty-one century, the development and the application of microprocessor technology, information communication and electric power and electronics technology have accelerated the research and the development of intelligent low-voltage apparatus products. The improvement of automation degree of industry system and the. largeness of system have made the number of low-voltage apparatus used in a system increase, so as to make reliability analysis of low-voltage apparatus more and more important. Electronic over-load protective relay is a type of important low-voltage apparatus product used for protection of asynchronous motor. The research of intelligent technology and reliability analysis of electronic over-load protective relay will be an important development direction on protection of motor in all of the countries in the future.This paper researched and discussed the intelligent technology and the reliability analysis of electronic over-load protective relay. On one hand, applying symmetrical component method, this paper analyzed all kinds of failure modes of asynchronous AC-motor, established related protective characteristic equations, designed corresponding intelligent protective circuit and compiled protective program in order to automatically choose an optimum protective mode to realize reliable and efficient protection according to running state of motor, at the same time, designed communication interface to realize remote bi-directional serial communication between electronic over-load protective relay and central control computer; On the other hand, using fault tree analysis (FTA)method, this paper carried out reliability analysis of the intelligent electronic over-load protective relay, based on the result of qualitative analysis and quantitative calculation, put forward some measures of improving reliability of electronic over-load protective relay.