Research On Direct Current Measuring Module Of The Electrical Quantity Transducer Calibration Device

The calibration device is a requisite device which is used for checking and ensuring the quality of the electrical quantity transducer. To meet the need of the market, the design and manufacture technology of the electrical quantity calibrate device is improved rapidly. In this paper, according to Heilongjiang measuring academe'index, the direct current (d.c.) measuring module is designed adopting to the latest measuring theory. The accuracy of the d.c. measuring module can achieve 0.01%. A Microprogrammed Control Unit (MCU) system which can test volts d.c., direct current, peak to peak amplitude of the measured quantity is implemented. The whole system has the integrated functions of data process, communicate, display, etc.During designing the hardware, in order to improve the whole system's interference immunity, the advantages of Small Outline (SO) chip is fully considered by proper redistribution, the analog parts and digital parts are separated by optoelectronic isolator to reduce the interaction. The high speed MCU C8051F120 includes a multiply and accumulate engine (MAC) which can be used to speed up mathematical operations, design control, display circuit and process data. The precision amplifier and sixteen bit analog/digital (a/d) convertor AD7677 are used in designing data collection module which can convert range automatically. Based on analyzing the error source, a method is proposed in this paper which uses Oversampling and Average filter to improve the system's stability and accuracy. At the same time, the cost of the hardware is reduced.During the debugging, the module is working well and can meet to the demands of the performance. So it is sure that the electrical quantity transducer calibration device with high performance-Price-Ratio will bring fresh vigor to the design, production and market of the related industry.