Preparation Prior to Zero Point Adjustment: Turn on the device and let it warm up for at least half an hour so that the internal analogue circuitry can fully stabilise thermally. This will stop temperature changes from causing more zero-point drift mistakes.
To prevent signal interference from external devices impacting the precision of the zero-point adjustment, disconnect any external loads and leave the signal generator output port unoccupied.
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 Reset Operation: To enter zero-point adjustment mode, navigate to the signal generator system calibration menu and choose the "Zero Point Calibration/Drift Reset" 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. This completes the basic zero-point reset.
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 correction, 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.
The entire channel mimicked a temperature signal of 0°C when the hot runner temperature control mechanism was installed. It was verified that there were no signal jumps or problems with zero-point misalignment in any of the temperature control channels. The zero-point adjustment was finished.
