Differential Temperature Measurement
Differential Temperature Measurement
(OP)
I am looking to measure a differential temperature of about 10 degrees F delta at around 0 F ambient with a reasonable amount of accuracy in a lab environment. I need to do this because I am using a single loop controller incapable of accepting multiple inputs and computing a difference. It seems to me that using 2, 2-wire RTD's in parallel (one as cold, one as ref) wired to a 3-wire RTD to 4-20mA converter would work assuming the RTDs are matched in length and type so the reference resistance in each circuit is the same. Would this work? Is there better ways of measuring a delta T?





RE: Differential Temperature Measurement
Also, Bob Pease has a number of articles about it. Check the National website for his articles and also any available app. notes.
Both men have achieved accuracies of better than 0.1ÂșC with some rather common components.
RE: Differential Temperature Measurement
BUT, you'll need to watch out for ALL the other contacts for thermal voltages.
TTFN
RE: Differential Temperature Measurement
RE: Differential Temperature Measurement
RE: Differential Temperature Measurement
just order matched pt-100's. it only cost a few bucks to have the factory check the cal. with NIST traceable standards. forget "jury-rigging" the rtd transducer. there are special transducer setup for differential temperatures, otherwise use two single input designs.
once you are past the sensor part, you need to deal with the installed accuracy of your meas. associated with sensor placement and conduction errors. you've not indicated what your response time requirments nor your accuracy requirments.