In order to prevent extra zero-point drift mistakes caused by temperature changes, turn on the device and preheat it for at least half an hour. This will allow the internal analogue circuitry to fully stabilise thermally.
To avoid signal interference from external devices influencing zero-point calibration accuracy, disconnect any external loads and leave the signal generator output port unloaded.
As the traceability reference for zero-point measurement, prepare a reference process calibrator with an accuracy class > ±0.01% and link it to the signal generator output port.
Basic Zero-Point Zeroing Operation: To enter zero-point adjustment mode, navigate to the signal generator system calibration menu and choose the "Zero-Point Calibration/Drift Zeroing" function.
In the current unloaded condition, wait for the device to autonomously gather the actual zero-point output value. Verify the difference between the theoretical zero-point value and the actual zero-point value as determined by the reference calibrator. This deviation will be automatically adjusted by the device to zero.
Verify the effectiveness of the zero-point correction by hand. Currently, the reference calibrator's zero-point output deviation must be less than 0.01% of the range. The fundamental zero-point zeroing is now accomplished.
Zero-Point Adjustment for Thermal Situations
Voltage Signal Zero Point: Verify that the deviation of the reference calibrator measurement value is ≤±1μV and set the output to 0V DC voltage. Finish the voltage channel's zero-point calibration.
Current Signal Zero Point: Verify that the deviation of the reference calibrator measurement value is ≤±0.001mA and set the output to 0mA DC current. Finish the current channel's zero-point calibration.
Thermal Signal Zero Point: Set the output to the RTD resistance value and thermocouple millivolt value that correspond to 0°C. Verify that, in accordance with the hot runner temperature control calibration scenario, the temperature variance shown by the system is ≤±0.5°C.
Verification of Zero-Point Stability: Following zero-point calibration, allow the apparatus to stand for half an hour before taking another measurement of the zero-point output value. Verify that there is no zero-point bounce and that the zero-point offset is ≤0.02% of the range.
Measure the zero-point value every fifteen minutes while running continuously for an hour. Verify that within an hour, the zero-point drift is less than 0.03% of the range, with a stable zero-point state and no ongoing offset.
All channels emulated a 0°C temperature signal, and the hot runner temperature management system was included. It was verified that there were no signal jumps or problems with zero-point misalignment in any of the temperature control channels. After that, zero-point calibration was finished.
By swiftly removing zero-point reference errors and providing a solid basis for later full-range accuracy calibration, this easy-to-implement calibration procedure keeps zero-point drift from leading to erroneous hot runner temperature control verification.
