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Temperature Q&A with J.R. Madden: Accurate Differential Temperature Readings

Temperature Q&A with J.R. Madden: Accurate Differential Temperature Readings

Senior Applications Engineer J. R. Madden has extensive experience with all things relating to temperature. In this recurring feature, he'll address common customer issues and Moore Industries' solutions.

Q: How do I measure differential temperature very accurately?

A: Whenever accuracy is the goal you want to start with RTDs (temperature range permitting). Many temperature transmitters will accept two RTDs and output the difference between the two inputs. However, if you look closely you will find they only make 3-wire RTD measurements and you may have errors and drifts due to wire length and corrosion build-up over time.

To maximize accuracy you need a device that can take in two true 4-wire RTD measurements and calculate the differential without losing accuracy. One such device is the NCS NET Concentrator System®, which has been employed in many successful applications. It also offers 20-bit A/D resolution on the inputs, 18-bit resolution on the D/A output and the RTDs can be bath-calibrated to eliminate the final sensor error.

Have a temperature-related application question you’d like J.R. to answer? Email us and we’ll address it in a future blog post.

Published: April 1, 2015