Some companies purchased pressure transmitters that allow 100-fold range migration. After migrating the transmitter range downward by 20 times, they found that the transmitter had poor stability. After restoring the standard range, no transmitter stability problem occurred.
What is the reason? In this article, we will talk about the factors that cause the stability of pressure transmitters to deteriorate after the range is migrated downward, which will help you to correctly migrate the transmitter range.
1. Downward migration means reducing the sensor’s range and signal output amplitude, which will inevitably increase the amplification factor of the signal processing circuit or reduce the sampling accuracy of the analog-to-digital converter.
This is one of the reasons for the decrease in the stability of the pressure transmitter.
2. If the transmitter range is moved down by 20 times, that is, the range is reduced by 20 times, then the basic error, temperature coefficient, and self-heating oscillation drift per unit time of the transmitter, these three fixed technical indicators, will increase by 20 times relative to the future range!
Therefore, the drift that can be ignored under the standard range becomes a major factor affecting stability that cannot be ignored after the range migration.
For example, if the comprehensive temperature coefficient of a pressure transmitter is 0.03%FS/℃, then relative to the range after migration (i.e. 1/20 full scale), 0.03%FS/℃=0.03%×20×(1/20 full scale)/℃=0.6%×range after migration (i.e. 1/20 full scale)/℃=6%×range after migration/10℃.
In short, if the temperature does not change by 10℃, the range error will be as high as 6%.
3. The range migration ratio of the pressure transmitter should not usually exceed 5:1.