Measuring Temperature with RTDs – A Tutorial

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_____________________________Product and company names are trademarks or trade names of their respective Copyright 1996 National Instruments Corporation. All rights 1996Application Note 046Measuring Temperature withRTDs A TutorialIntroductionA resistance- Temperature detector (RTD) is atemperature sensing device whose resistance increaseswith Temperature . An RTD consists of a wire coil ordeposited film of pure metal. RTDs can be made ofdifferent metals and have different resistances, but themost popular RTD is platinum and has a nominalresistance of 100 at 0 are known for their excellent accuracy over awide Temperature range.

Temperature Scale (ITS-90) that is used with wire-wound RTDs (αÊ=Ê0.003925). The Callendar-Van Dusen coefficients for each of these three platinum RTD curves are listed in TableÊ1. RTD Measurement Circuits. Because the RTD is a resistive device, you must drive a current through the device and monitor the resulting voltage. However, any ...

  Temperatures, Circuit