Abstract:Residual current of each phase in the low-voltage distribution lines (including neutral) current vector sum of the current is not zero. Nowadays, computer technology is already very mature, of its high integration, strong function, large storage capacity, fast speed, strong anti-interference and rich in instruction and other advantages, it is applied widely in various fields. The system is designed in single chip microcomputer application in fire monitoring as an example. This system is a kind of high precision, fast speed control in the application of relatively strong residual current fire monitoring system.
The design uses the AT89S52 single-chip microcomputer as the control core, through the production of the hardware circuits and software programming, the realization of a fire control system. The system includes a signal acquisition module, the temperature acquisition conditioning module, A / D conversion module, an external display module, clock module, the alarm module and storage module.In the forward channel through a thermistor ( PT100) on the temperature of the collection. Another way, the residual current mutual inductor current to be measured, is converted into DC voltage. The two road collected data into a digital signal converted by the A/D converter module, single-chip processing, the display shows the current value and temperature value, the buzzer will alarm when the current exceeds the set value.
The system software uses C language modular programming. The response speed of the system is relatively quick, but also has the advantages of low power consumption, good reliability. So this system has very strong application, suitable for building electric fire monitor.
Key words：single-chip microcomputer, residual current, A/D convert, thermistor(PT100)