Desing and implementation of a microcontrolled multimeasurement device

DESIGN AND IMPLEMENTATION OF A MICROCONTROLLED MULTIMEASUREMENT DEVICE(M. Sc. Thesis)Ali Tolga NANDIGAZ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYSeptember 2006ABSTRACTToday, usages of digital measurement devices are extremely widespreadin electrical measurements. Systems, using power semiconductordevice, have nonlinear current and introduce voltage harmonics into thesupply line. Therefore meters adjusted for linear load can causeincorrect measurement. On this point, true root-mean-square (rms) valuebecomes increasingly important. Although Integrated circuitriesdesigned for measuring rms derive output voltage proportional to inputrms value, these don?t give any information about input waveform. In thisthesis, instant values of alternative current and voltage are used tocalculate true rms values mathematically by microcontroller. In order touse in signal analyzing, instant values of three-phases? voltage andcurrent are sent to computer on serial port. Graphics are plotted frominstant values of three-phases? voltage and current sampling series. PIC18F4455 is used to show current, voltage, power factor, active power,reactive power, imaginary power and frequency value of three phasessystem on 4*40 LCD at the same time. For measuring frequency andpower factor, sinus signals have been converted to square wave voltageusing comparative circuit. Then frequency and power factor have beencalculated from zero transition point. Operating frequency ofmicrocontroller is 48 MHz and speed of data transmission on serial portis 115200 bit/s. Therefore system operates sensitively. Thismeasurement device is designed for producing electrical values ofsystem. The data can be used for statistical calculations. Experimentalresults show that the system operates efficiently.Science Code : 703.3.012Key Words : PIC, power , frequency , rms , voltage ,current,Page Number : 117Adviser : Prof. Dr. Çetin ELMAS