Characterization of Small Industrial Temperature Sensors

The Space Dynamics Laboratory (SDL) has observed, over several years of work with various blackbodies, significant unexplained calibration drifts in some industrial PRTs. With a mandate to build more accurate calibration sources with tens of millikelvin accuracy, SDL began an effort to understand the calibration drifts in small temperature sensors less than an inch long. Testing was performed mainly by cycling PRTs and thermistors through a range of temperatures in a thermal bath, with further results obtained once the sensors were placed in a blackbody. The key result is that temperature sensors routinely drift during thermal cycling, with some sensors drifting more than others. Because even sensors from the same batch can vary, it is important to screen sensors before using. In addition, it is best to calibrate sensors after they are mounted in a fixture, and some PRTs were found to be highly sensitive to handling.