Research On Synthetical Protection Technology Of Intelligent Circuit Breaker

Circuit breaker is an important kind of low-voltage protective device, which is widelyused in low voltage distribution power grid. With the rapid development of social economicand the continued growth of power supply, Put forward higher requirements to the qualityand reliability of power supply. when the power supply circuit failure, The circuit breakercan not only detect the residual current of50Hz sine wave accurately, but also dectect apulsating DC residual current, which contains a half sine wave(half-wave)、a90°triggerangle wave(90°-wave) and a135°trigger angle wave(135°-wave). and reliable protection toover-voltage or low-voltage failure, over-current failure, short circuit failure and otherfailures that occurred in power supply line. Therefore, it is very important to study on theresidual current device which can meet the above demands.Firstly, an detail introduction of the development of the residual current operatedprotective device is given, and the circuit breaker’s principal diagram is briefly introduced.Secondly, the hardware circuits are designed, including switching power supply circuit,Residual current detection circuit, Voltage detection circuit, Current detection circuit,Auxiliary pulse circuit, Tripping device driver circuit, RS485communication circuit andDisplay/key circuit. The involved schematics, devices, parameters are described in detail,some circuits are simulated and measured. At the same time, The paper discusses theproblem of electromagnetic compatibility, and analyses the relevant test requirements andsolutions.Thirdly, the software is designed based on dsPIC30F6012A, completed the softwarewriting of signal sampling, fault diagnosis, serial port interrupt, LCD/buttonsrespectively through adopt modular programming method.Finally, It is verified by experiments that the prototype can meet the requirement ofthe protection technology, and electromagnetic interference tests are passed.