Overall Design Of Intelligent Molded Case Circuit Breaker Trip

Molded Case Circuit breaker is used to connect or cutoff power line and protect and control many kinds of faulting, it can be widely used in the low-voltage distribution system. The trip relay executes the function of breaker, it having the functions of overload protection , short-circuit protection, grounding protection,residual current protection and so on. Aimming at the defect of long-time lasting, low-precision and difficulty of adjusting of the traditional circuit breaker, the article provides the measuring ways and protection algorithm of the intelligence trip relay, and make the design of hardware and software. The purpose is to realize the intellectual protection, remote control and concentrate management of circuit breaker.This paper dissertates the theory of designing an intelligent in details, includes the sampling sensors of electrical parameters, the method of calculating the value of parameters, all protective functions and the mathematic model of these functions. Based on the theory, the designing method of the MCU system and other peripheral blocks was established. Through the synthetic design of hardware and software of the system,aim at realizing various kinds of functions, such as measurement, monitorin, controlling, communication, protecting of the intellectual controller, etc. In this paper, the designing information of blocks is discussed detailed in hardware and software.Among this subject, this intellectual trip relay regards MCU chip Atmega16 which Atmel Company produces as the key processor on the hardware, it is mainly deal with trouble protection in circuit breaker and gathering data in real time. The software adopts the module design method, uses the assembler language programming way, As some measures of hardware and software are used in the system, the stability and reliability of release are achieved.The question of saturatd of Current Transformer for Intelligent Molded Case Circuit Breaker in large current.The software revision method of current transformer was presented. Actually measurement and imitational data were given. Revision result shows that this method with high precision and reliabilitymake design simple in practical application.Low voltage electrical apparatus RS-485 serial communication interface was designed and the communication capable technology of low voltage electrical apparatus was studied. the inter communication between the local intelligence trip relay and computers and remote communication, remote measure,remote adjustment , remote control with Modbus Protocol, which makes the electrical apparatus more correspond with the automation of power system was realized.