Transmitter zero, span adjustment:
Before adjusting, turn the damping potentiometer to the end counterclockwise (that is, turn off the damping effect). After turning on the power for 15-30 minutes, adjust the zero position. When the input differential pressure is 0, the output of the transmitter is 4mA, that is, the voltmeter indicates 1 ± 0.004V. Then add a differential pressure signal equivalent to full-scale output, adjust the range potentiometer (turn clockwise, the output increases, and vice versa decreases), so that the transmitter output is 20mA, that is, the voltmeter indicates 5 ± 0.004 V. Note that the zero position will be affected when adjusting the potentiometer, but the range will not be affected when adjusting the potentiometer. Therefore, you need to adjust the zero position once after adjusting the measuring range.
Generally, the transmitter is calibrated when it leaves the factory. It can also be used when high linearity is required and precision standard instruments are available. The steps are as follows: After adjusting the zero and range, add a differential pressure signal equivalent to one-half of the range. At this time, the output should be 12mA, that is, the voltmeter indicates 3 + 0.004 V. If it does not meet the requirements, adjust the linear Degree potentiometer, make the output meet the requirements, and then repeatedly check the zero position, range and linearity until qualified.
First adjust the range to the required value, such as 1000-2500mmH20 measurement range. Then first adjust the range to 0-1500mmH2O. If the beginning of the range shift is the least, you can directly adjust the adjustment potentiometer to achieve the migration. Such as the largest migration. You need to set the positive and negative migration switches in the safety junction box to the corresponding positions (note that you cannot turn both switches to the “ten” and “one” symbol ends), and then add a stable differential pressure at the beginning of the input range Signal, adjust the zero potentiometer to make the output to 4mAo
Check that when the input pressure difference is the upper measurement limit (such as the aforementioned 2500mmH2O), the output should be 20mA. Otherwise, the full-range potentiometer can be fine-tuned.
The so-called damping, that is, the response speed of the transmitter's output with the measured pressure difference. Generally adjust it according to the fluctuation of the output of the transmitter when using it in the field. Use a small screwdriver to insert it into the damping adjustment hole. Rotate the potentiometer handle and turn clockwise to increase the damping time. However, when turning to the end, do not use force to re-spin to avoid damage to the potentiometer.