Preparation Before Calibration: Power on the device and preheat for at least 30 minutes to allow the internal analog circuitry to fully stabilize thermally and avoid additional calibration errors introduced by temperature fluctuations.
Prepare a reference process calibrator with an accuracy class ≥ ±0.01%. Its accuracy class must be at least two classes higher than the signal generator being calibrated, serving as a traceability benchmark for accuracy comparison.
Connect all test cables, ensuring they are secure and not loose. Ensure the device is reliably grounded and that electromagnetic interference is eliminated.
Step 1: Zero-Point Self-Calibration
Disconnect all external loads and leave the signal generator output port unloaded. Enter the system calibration menu and select the "Zero-Point Calibration" function.
Wait for the device to automatically acquire the actual zero-point output value under the current unloaded state and automatically zero the zero-point deviation compensation.
Use the reference calibrator to confirm that the zero-point output deviation is ≤ 0.01% of the range. Zero-point calibration is complete.
Step 2: Full-Range Gain Calibration
Set the signal generator output sequentially to 10%, 25%, 50%, 75%, and 100% of the range, and measure the actual output value point-by-point using a reference calibrator.
For the output deviation at each range, manually adjust the gain correction coefficient of the corresponding channel to eliminate nonlinear deviations across different range segments, ensuring that the full-range output deviation is ≤ the equipment's nominal accuracy.
Specific calibration of thermal signals: Calibrate the thermocouple millivolt output and RTD resistance output point-by-point to correct temperature simulation signal deviations and meet the calibration requirements of the hot runner temperature control channel.
Step 3: Stability Verification
After calibration, run continuously for 1 hour, collecting output data from key calibration points every 10 minutes to confirm that the drift within 1 hour is ≤ 0.03% of the range, with no continuous offset.
Connect to the hot runner temperature control system and perform a full-channel linkage test to confirm that the difference between the temperature control system display value and the signal generator output value is ≤ ±1℃, with no signal jumps or communication interruptions.
Once all verification items meet the standards, save the calibration parameters to the device's non-volatile memory, generate a calibration record for archiving, and the device is ready for official use.
This self-calibration process is clear and easy to implement; ordinary industrial control system maintenance engineers can complete it independently without additional complex tools, ensuring that the calibration accuracy of the hot runner signal generator meets production line requirements.
