Design Of Alarm And Control System For Electric Fire Protection Based On ZigBee

Alarm and control system for electric fire protection is one system sending alarm and control signals, and specifying the alarm location when the detected value of the protected circuit is bigger than the pre-set alarm value. With economic developing rapidly and living standard improving greatly, electrical equipments are constantly increasing, as well as the use of electricity load, followed by those fire accidents are also increasing year by year. Because alarm and control system for electric fire protection can monitor failures and anomalies of the electrical circuit, detect fire hidden danger, send alarm signals and inform the monitor to eliminate these risks, its emergence has aroused widespread concern. But in some special cases, it costs high for laying and maintening circuits in the traditional system, and the wire itself is often corroded, which will affect the communication quality. In these circumstances, the use of wireless communication technology can solve the technical problems.With the development of the electronic communications, wireless communication technology has also been in considerable progress. The paper begins with the wireless communication technology in the alarm and control system for electric fire protection. Through researching the characteristic of main wireless communication protocol, ZigBee is choosen as lower communication protocol. ZigBee is a new technology with low complexity, low power consumption, low data rate, low cost wireless networking for short range wireless communication. The main areas of its application include industrial control, consumer electronics, automotive automation, agriculture automation, medical equipment control and so on.The paper describes the basic knowledge related to the alarm and control system for electric fire protection and the ZigBee technology, introduces the general knowledge of ZigBee wireless technology and analyses its protocol stack structure, researchs various communication protocol layer functions and roles in ZigBee network, designs the software and hardware platform in keeping with ZigBee protocol, develops ZigBee protocol stack. In the data transmission of alarm and control system for electric fire protection, ZigBee wireless network becomes a part of RS-485 cable transmission network. Eventually the respective merits of wired and wireless transmission are combined powerfully. ZigBee wireless communication is used in the case that the wired transmission is limited. The wired transmission is used in the areas where the wireless signal is shield. Both with each other to make up for deficiencies. In the data transmission of ZigBee network, point-to-point communication is chosen. Setting up the routing table of the monitoring devices addresses and judging the data in different levels are to ensure the data real-time, completeness and accuracy. It also designs and develops the parameters of residual current collection, as well as other show and control circuits. Putting the three-phase lines and middle line of the electrical circuit through the zero current transformer,the residual current signal will be converted into the voltage signal.In this paper, the residual current is measured through putting the signal converted by the zero current transformer and the precision rectifier circuit into the single chip ADC module, and the single chip deal with the data finally. The value of temperature is collected by measuring the value of the platinum resistance that changes with the temperature in unbalanced bridge. A appropriate data sheet is made on the basis of voltage corresponding to the different actual temperature. The single chip deals with the voltage signal and obtains the final temperature by the data sheet. Finally, the paper develops a host computer server program in use of Qt technology. The program connected monitor equipments and ZigBee modules by RS-485 lines so as to complete the communication of the entire system.The experiment has demonstrated this alarm and control system for electric fire protection based on ZigBee wireless technology can monitor faults and anomalies of electrical circuits, and can inform the monitor to remove the hidden dangers.