Research On Average Temperature Measurement By Change-in-resistance Method

When measuring the temperature of an object, usually various kinds of sensor wereused to measure the temperature on the surface. However, for winding of transformer orother electric conductive object with complicated construction, it’s more important toknow the internal temperature than that on the surface only. The change-in-resistancemethod is quite convenient and effective to measure the internal temperature under thesesituations.The change-in-resistance method is to measure the temperature by measuring theelectric resistance of the object and calculating the corresponding temperature according tothe known relationship between temperature and electrical resistivity. Since mostly theresistance is to be measured after removing the power and the resistance has started todecrease, the measured data should be processed and extrapolated to the resistance of theobject which is normally operating with power.This work analyzes the physical laws of cooling, discusses critical coolingenvironment and conditions and creates typical models of cooling. The cooling process isdeeply researched using the electric circuit to simulate the operation of cooling models.Based on the research, correct data processing and curve fitting method is discussed andsummarize how to avoid the common seen incorrect result. All the conclusions provide thetheoretical basis for laboratories to work out the correct test procedures.