Research On5.3A/380V Contactless Control And Protective Switching Device

Along with electrical environment become more complicated, the traditional typecircuit breaker has been difficult to meet the market and technical requirements, andcontrol and protective switching device as the new integrated electric which is applied tolow voltage power distribution and control system emerge as the times require. It integratesthe circuit breaker, contactor, thermal relay, starter, isolator and other electrical functioncollection in a body and has many advantages, such as small volume, complete functions,high reliability, control and protection coordination and convenient operation. At present, thedeveloped control and protection switch has a series of problem, such as time delay inperformance, low sampling precision, tripping mechanism is not perfect, the auxiliaryfunction is not abundant enough and so on, and they are more for the electromagnetic typecontact switch, this kind of switch may produce spark and arc between contacts in theclosed and shutdown period, wear contacts, and produce surge current larger easily. Thisstudy proposes a new multifunction contactless control and protective switching based onMCU, improve various performances.In this paper, based on the requirements for control and protection switch, an overloadinverse time protection, short circuit protection, phase lack protection, leakage protection,over-voltage and under-voltage protection and digital display of rated current scenedetection and alarm function for5.3A contactless control and protection switch is proposed.Through the comparison of various types of power electronic switching devices available,choose IGBT as switching equipment.Because the control and protective switching devices with various protectionfunctions, so it is piecewise different strategies, this research is based on the PIC16F877AMCU as the core control device, the power supply circuit, data control system real-timeacquisition circuit, output control circuit, a switch main circuit and display and alarmcircuit is designed, and the design of acquisition circuit current rate of change based on theMultisim10software, simulation results show that, this method can greatly improve the detection rate of short circuit fault. Write the software program design in addition thisfollows a modular, which is divided into initialization, data acquisition, data processing,fault protection and display several subroutines, were combined after finished debugging,the software design of the system.Finally, based on the design of the hardware and software, make a part of hardwarecircuit for the corresponding experiments, the experimental results show that it can meetthe design requirements, to achieve the desired effect.