Yes, the specific steps for PT100 calibration include preparing standard equipment, setting up the environment, selecting calibration points, performing multi-point measurements, data processing and error correction, and finally generating a calibration report. The entire process must strictly follow the IEC 60751 standard to ensure accuracy.
Calibration is a core step in ensuring the long-term accuracy of PT100 sensors, especially crucial in industrial control, medical equipment, and new energy systems. The following is a detailed and executable standardized operating procedure:
I. Preparation Before Calibration
Standard Equipment List
Standard Platinum Resistance Thermometer (Class II or higher accuracy)
Thermostatic Bath: Freezing point bath (0℃), water bath (0–100℃), oil bath or salt bath (>100℃)
Four-wire digital multimeter (accuracy ≥0.01Ω)
Shielded connecting cable, insulation resistance meter, PID temperature control system
Environmental Requirements
Temperature: 20±5℃, relative humidity ≤80% No strong electromagnetic interference, vibration, or airflow disturbance
Inspection of the Sensor to be Calibrated
No external damage, no oxidation of leads
Insulation resistance ≥100MΩ (tested using a megohmmeter)
Ensure the probe is clean and dry
II. Calibration Point Selection
Determine the calibration temperature point according to IEC 60751 standard and actual application requirements:
|
Calibration Type |
Recommended Temperature Point |
Applicable Scenarios |
|
Basic Calibration |
0℃ |
Quick verification of zero drift |
|
Regular Calibration |
0℃, 100℃ Industrial general-purpose, for evaluating linearity |
|
|
High-precision calibration |
0℃, 50℃, 100℃, 200℃, 300℃ |
Suitable for laboratory, pharmaceutical, and metrology applications. |
Fixed-point calibration: Triple point of water (0.01℃), freezing point of tin (231.928℃). Traceable to national standards.
It is recommended to include at least the upper stroke (heating) and lower stroke (cooling) tests to evaluate hysteresis error.
III. Specific Operating Procedures
Step 1: 0℃ Calibration (Freezing Point Bath Method)
Pour the ice-water mixture into the freezing point bath and stir thoroughly.
Insert the PT100 sensor to a depth ≥30mm.
Wait for the temperature to stabilize (fluctuation ≤±0.02℃/10min), the standard value should be 100.00Ω.
Step 2: 100℃ Calibration (Constant Temperature Water Bath Method)
Set the constant temperature bath to 100℃, horizontal temperature field uniformity ≤0.01℃.
Insert the PT100 and standard sensor together, avoiding contact.
Equilibrate for 10–30 minutes and record the readings.
Step 3: High Temperature Point Calibration (e.g., 200℃, 300℃)
Use an oil bath or salt bath, controlling the heating rate ≤5℃/min.
Measure the resistance value after each temperature point stabilizes.
The high-temperature section needs to be placed in a glass or quartz test tube to prevent contamination.
Step 4: Cooling and Retesting (Optional)
Slowly cool down from the highest temperature point.
Measure again at the same temperature point to evaluate the hysteresis error.
