Calibration of standard smart pressure transmitter and smart differential pressure transmitter
Author: Source: Date: 2021-05-22 14:17:05
1. The pressure transmitter is ready to work. The negative pressure chamber keeps rotating. We know that some types of differential pressure transmitters will take over the exhaust, drain valve or rotating plug of the positive pressure chamber. Preliminary calibration after power warm-up. The positive and negative pressure chambers have exhaust, drain valves or rotary plugs. Close the balance valve, first close the positive and negative valves of the 3-valve group to pass the atmosphere. In the future, empty the exhaust machine, drainage valve, and rotary plug, open the balance valve, calibrate the differential pressure transmitter, and then connect the ammeter (voltage meter) and the manual machine to the transmitter input circuit to check the air tightness. In other words, the pressure source through the rubber tube is consistent with the low-price exploration, and the differential pressure transmitter can be calibrated without eliminating the draft tube. This provides convenience for us to calibrate the differential pressure transmitter on site.
2. The calibration of the ordinary differential pressure transmitter will be adjusted upwards by 1mA, and vice versa. First adjust 0. When it is not migrated, the impact is about 1/5 of the dispatch amount of distance adjustment. When it is adjusted to 0, it has little impact on 10,000 degrees. The on-site adjustment speed is fast. The output is 20 mA. You can choose 0 o’clock and distance. Quick adjustment method.
3. The calibration of smart differential pressure transmitter cannot use the above general method to calibrate smart transmitter. This is because of the principle of the structure of the HART inverter. Because the smart transmitter is in addition to the machine and circuit between the input pressure source and the generated 4-20mA current signal, it also performs the calculation of the input data on the micro-processing chip. Therefore, the adjustment is different from the general method. Moreover, the "barite" monopoly applied to connect the transmitter to a standard pressure source. In fact, the calibration of the smart transmitter is also very bright. Therefore, when correcting reality, you can proceed in sequence: as follows. A series of English instructions can be used to wake up. Each small part must be calibrated by itself and must be coordinated, so the "setting range" is mainly through LRV. However, it can be seen that the relationship between the simulated input of the transmitter and the input value used is correct, but the initial and final setting of the range directly depends on the correct pressure input value. The setting can be completed through the digital setting of URV, but the digital reading of the process value is slightly inconsistent. There are 3360 "setting range", "financial amount range" and "fine adjustment" for calibration. Like ABB's transmitter, the transmitter directly senses the actual pressure and sets the value. 1. First, perform 4-20 mA fine-tuning and calibrate the D/A converter inside the transmitter. Because sensor components are not included, no external pressure signal source is required. 2, 4-20 mA, a pressure signal source is needed, because the digital reading will be fine-tuned again to make it match the pressure signal in the actual application. 3. Finally, by adjusting the liquid crystal, the analog output 4-20mA is matched with the additional pressure signal source, which plays the role of 0 adjustment (z) and distance adjustment (r) switches of the transmitter housing. The above is the different adjustment instructions of the standard smart pressure transmitter and the smart differential pressure transmitter. Next time you encounter the adjustment of the smart pressure transmitter and the smart differential pressure transmitter, pay more attention to the adjustment differences between them.