Basic procedures on how to calibrate a temperature probe

To calibrate a PRT, PT100, or RTD using a dry-block calibrator or calibration bath, there are five steps you usually need to follow:

1. Place the reference probe and the probe you’re calibrating in the temperature source. Try to keep them close together, in a circle, with the reference probe in the center.

2. Connect the leads to the readout that measures the probes. This may be the calibration readout or it may be the readout that is paired with the probe.

3. At each test point, measure and record the reference probe temperature and the temperature of the probe you’re calibrating as well as the equipment settings. In higher level PRT calibration you may need to measure probe resistance also so new adjustment parameters can be calculated as part of the calibration.

4. Verify the DUT error to know if it is in tolerance or not.

5. If necessary, use the calibration results to calculate new adjustment parameters for the probe being calibrated. This is the process of solving a set of equations that contain the calibration data to find a set of coefficients unique to the RTD and calibration. It’s easiest to invest in software that can do this.