CPS Control And Protective Switch Design

As the development of national economy, the requirements for distribution network, control system and safe and reliable running of motors has been increased highly, conforming to this trend in80s, control and protection switch is developed as new integrated of electric in low voltage distribution and control system area.it combines all the functions which the breaker, Contactor, Isolator and fuse have. It has a number of advantages such as small volume, complete functions, high reliability, control and protection coordination and easy operation, and overcome some defects such as low reliability and unreasonable coordination of protective characteristics coursed by the combination of the variety of electrical goods. Now, control and protection switch need current transformer with different ranges to test currents which will cost a lot and is hard to operate.This article promotes full current testing with programmable gain amplifier based on the traditional control methods, through a combination of the DS3904and LM358, it achieves wide range current detection, making it possible to provide facilitate and efficient protection to the system, and reduce production costs.This article takes MCU STC12C5A48S235as the core to accomplish the design of hardware of multifunctional protection module, software of micro-computer, remote control software in computer. Prior to this, Matlab/Simulink has been used to simulate failures of motors in order to get references serving to protect the CPS control and protection switch, moreover, circuit simulation has been done initially in the Mutisimll to verify whether the circuit design is reasonable or not.based on using PROFIBUS connection of RS485, the functions of the slave and the host are assigned, and the communication protocols between the host and the slave are established.in the segment of the design of the hardware for micro-computer, due to the easy design, the whole Module has been divided into many small parts, and data acquisition and processing module, remote communication modules, keyboard module, display module, and breaking has been designed separately, and then accomplish to compile the program for micro-computer following the procedures for modular design and describes how to use human-computer interaction to realize parameter setting and reading, analysis of the data.By comparing various database and data access technologies, the technology of ADO is selected to access to store fault information and data related to voltage, current, leakage current. And realize remote telemetering, remote signaling, remote regulating, remote control and alarm/trouble shooting features. Which is very convenient for the customers to collect the current, the leakage current, the voltage, the failure information and so on. Meanwhile, which can cut off the circuit due to protect the motors. By using a programmable gain amplifier, it can be adjusted by Micro-computer based on the currents. Which has decreased the quantity of current transformer, cut down the cost, be operated easily and realize full range currents testing.Finally, CPS control and protection switch has been tested by various failures. As certified by the test, CPS control and protection switch can protect appliance effectively when the failure occurs, and can achieve full range current protection and remote control.