Calibration is carried out using analog signal comparison methods

The expert group’s comments actually highlight many typical mistakes that occur during the instrument calibration phase in various projects: using \"partial testing\" as a substitute for \"comprehensive verification\". Your method of operation (using a process signal generator) can only prove that the signal path from the input card to the DCS is intact, but it does not cover the potential problem area of the \"last mile\" – the field sensors. The standard method for \"analog signal comparison\" requires connecting a standard signal generator to the terminals of the field instrument (sensor/transmitter). The value of this method lies in the fact that it includes both the sensor itself and the connection cables to the control system within the scope of calibration. By simulating real physical quantity inputs, it verifies the accuracy and integrity of the entire measurement chain (from sensors to DCS displays), making it a key procedure to ensure the precision and reliability of the whole measurement circuit. 💡 Improvement suggestion: To gain the approval of the expert panel, the key is to change the signal injection point. At the same time, a more detailed \"Instrument Loop Calibration Record\" should be prepared, indicating the injection point information: it should be noted that the signal is injected at the terminals of the field primary instruments. Multi-point inspection: For each instrument, perform upward and downward checks at 0%, 25%, 50%, 75%, and 100% of the range, and record the upward and downward data. Error calculation: Calculate the total error of the circuit (the square root of the sum of the squared allowable basic errors of each individual instrument), and ensure that the measured error falls within this range. Only records that have been revised in this way can meet the regulatory requirements and pass the inspection successfully.