PT100 temperature sensor accuracy and probe classification

It is important to understand that, just like the K -type thermometer, there are three major uncertain areas in the use of the PT100 temperature timing.
1. Unit uncertainty
2. Uncertainty of probe
3. Uncertainty of any calibration program

1) The uncertainty of the unit
This is very good and simple, but often misunderstood. This is the accuracy of the device that actually explains the signal from the probe and displays the readings. This is the most commonly seen number in the product description. For our PT100 thermometer, from -80 ° C to 200 ° C is ± 0.05 ° C, and the range of other temperatures is 0.1 ° C. People often mistake it as the overall accuracy of the system, but that's wrong!

2) The uncertainty of the probe
This is where the matter becomes a bit complicated. Each probe has different levels of tolerance. IEC 60751: 2008 is regarded as international standards and specifies the tolerance of platinum RTD temperature sensor components. The standard specifies 4 precision levels. Class B, A, 1/3 din, and 1/10 din. Just as we are " resistance temperature detectors (RTD)?" Platinum RTD temperature sensor follows the temperature-resistance curve, which indicates which temperature in the resistance level in the sensor. Each probe has the ability to deviate from this curve, thereby reducing accuracy. The category of the probe determines that the probe can deviate from this curve.

For example, ... Class B probe should indicate a temperature of 0 ° C when the resistance is 100 ohm, but the tolerance is 0.3 ° C. The actual temperature may be between -0.3 ° C and +0.3 ° C. The 1/10 DIN probe should represent the temperature of 0 ° C under the resistance of 100 ohms, but the tolerance is 0.03 ° C. The actual temperature may be between -0.03 ° C to +0.03 ° C. Don't forget to add this to the accuracy of the unit to obtain the final accuracy. In the following example, we use our own PT100 model. Class B: (± 0.05 ° C + ± 0.3 ° C) = ± 0.35 ° C at 0 ° C 1/10 din: (± 0.05 ° C + ± 0.03 ° C) = ± 0.08 ° C AT 0 ° C. Show the tolerance of each level of probe at different temperatures. If you cross -refer to the temperature you may have to measure and add them to the tolerance of the PT100 unit, you can calculate the type of probe that is suitable for your application.

3) Uncertainty of calibration procedures
Calibration is an excellent tool to eliminate the uncertainty attached to each instrument. Your PT100 thermometer has been tested in accordance with the known reference standards and a calibration certificate is generated. For high -precision instruments, such as our PT100 model, we provide UKAS calibration services.

Based on our previous calculations, we know that in the standard calibration temperature point we provided, our own PT100 temperature sensor with Class B probe usually has the following accuracy uncertainty.

● -20.00 ° C ± 0.45 ° C
● 0.00 ° C ± 0.35 ° C
● 100.00 ° C ± 0.85 ° C
● 200.00 ° C ± 1.35 ° C
The calibration certificate shows a few key information.
1. Calibrate temperature-This is the temperature tested by the thermometer
2. VD100 thermometer read-this is the reading given by the PT100 thermometer at the known temperature
3. Calibration temperature point remaining uncertainty
Examples from the certificate
This will show the following (this is just an example)

The measurement uncertainty of the thermometer is. Numbers: below 255 ° C = 0.06 ° C -higher than 265 ° C = 0.11 ° C. This will not only notify the user to adjust the reading at the required temperature. It also reduces the uncertainty of each test point from ± 0.45 to ± 1.35 ° C to an amazing 0.06 ° C. The uncertainty is calculated by the UKAS guide and has about 95% confidence.