Temperature Transmitter Configuration and Calibration Guide
Temperature transmitters convert sensor signals into standardized outputs for control and monitoring. They can significantly improve measurement accuracy through sensor-transmitter matching.
I. Configuration
- Sensor Type: Set the transmitter to match the connected sensor type. Using the wrong type causes gross measurement errors.
- Measurement Range: Configure the Lower Range Value and Upper Range Value for the desired temperature range. The output scales linearly between these values.
- Sensor Matching: For RTD transmitters with sensor matching capability, enter the Callendar-Van Dusen constants from the sensor calibration certificate to achieve the highest accuracy.
- Fault Mode: Configure the output behavior on sensor failure: upscale (go to maximum output) or downscale (go to minimum output) based on process safety requirements.
II. Calibration
Using a Temperature Calibrator
- Connect the transmitter to a temperature calibrator that simulates the sensor output
- Apply signals corresponding to known temperatures at calibration points across the range
- Measure the transmitter output and compare with expected values
- Adjust the transmitter calibration if the error exceeds specifications
Trim Procedure
- Perform a sensor trim to align the transmitter input measurement with the calibrator reference
- Perform an output trim to align the analog output with the digital reading
- Verify both input and output at multiple points after trimming
III. Troubleshooting
Reading at Minimum or Maximum: Check for open or shorted sensor. Verify sensor type configuration. Check sensor connections.
Inaccurate Readings: Verify sensor type setting. Check for incorrect extension wire. Verify that sensor matching constants are correctly entered if used.
Noisy Output: Check for electrical noise pickup. Verify proper shielding and grounding. Increase damping if available.
