The Design And Development Of A Multi-rated And Prepayment Three-phase Watt-hour Meter Based On CPU Card

The multi-rate electric charge policy is broadly used in our country during these years.It can effectively ease the situation of power emergency, and regulate the electric power load curve. At the same time, CPU card technology is getting prompt extension and broad application, and coming into the prepayment electricity which can be a good way to solve some complex problems,such as meter reading, tariff reminders, the statistical power of information. My research is specifically made for this isuue, to develop a three-phase multi-rate prepayment watt-hour meter which is much-needed, its results could be expanded to other industries.Firstly, the three-phase power, the classic theory of power measurement and the CPU card communication technology and its working environment are analysed, moreover, the 3DES encryption algorithm is also construed.Secondly, the solution of the three-phase multi-rated prepayment watt-hour meter is expatiated in detail. The system adopts the high-accuracy measurement of power DSP chip ATT7026 as the measuring chip.Then use multi-rate special integrated circuits FM2307 which is rich in natural resources and has good anti-interference ability and low-power as the main controller, and expands CPU card communication function on the chip. This watt-hour meter is able to realize multi-event record, RS-485 and infrared feature.Thirdly, a three-phase multi-rated prepayment watt-hour meter is developed. The hardware design is divided into power module, measuring module, the main control module and the communications module, and interface between various modules and the anti-jamming hardware design is discussed.And the current exploitation implement and some sub-sector of software involving accumulation power, the time control algorithm, various communication ways are described.Fourthly, the clock accuracy, anti-interference designing, hardware and software checking method of the three-phase multi-rated prepayment watt-hour meter are discussed, the results of running the system is given. And instrumentation for measuring the accuracy and reliability of the operation is analyzed.The three-phase multi-rated prepayment watt-hour meter introduced in this paper works fine, it can achieve precise measurement between time switch and takes the CPU card as the carrier to develope a collect meter reading system.The measurement results shows that the watt-hour meter has strong anti-attack and anti-jamming ability, its main technical performance not only meets but also exceeds the current national standards, reaches the expected design.