High-precision Resistance Measurement Research And Design Of The Monitoring System

The study of materials science shows that, some new metal materials havethe different electrical properties in different temperature environment,especially, the property of their weak resistance. The change of theproperty of weak resistance may provide the theoretical evidence forseeking the new applications of the new materials.In this paper, we analyze the theory of weak resistance in differenttemperature environment. Based on this theory, we also design the systemof measurement and monitoring. So, the paper includes the research of weakresistance theory, the design of systems hardware and software.The main contents of this paper are as follows:Considering of the requirements of resistance measurement, we choose thefour-terminal wiring as the connection mode, in this way, the error ofwire resistance and contact resistance can be reduced effectively. Basedon the requirements of current signal, we select DC as the signal sourceof the system, and analyze the theoretical principle for this choice. Forwhich the main errors of the signal source are coming from the chemicaland thermal emf. In order to solve the drift error, we propose a new kindof method, which named the method of switching currents in use ofprogram-controlled relay.In the view of the above theory, we complete the selection and constructionof the hardware system, which contains the functions of measurement andmonitoring.After the completion of system hardware construction, the systemmanagement software is developed based on the serial communicationstandard RS-232 in using of the programming language Delphi 7.0 .In this software system, a series of functions are achieved, such as: drawthe curve of resistance, real-time monitoring, error elimination, settingparameters and parameters acquisition, and so on.The present paper also gives the experimental results in using this system,by which the weak resistance measurement of metallic materials indifferent temperature environments were completed. The results of theexperiment are effective and of high-precision, which support validityof theory.