Pressure sensor, process pressure transmitter, and, processes for measuring differential pressure, and for error compensation in measuring differential pressure, and in measuring process pressure

摘要

"PRESSURE SENSOR, PROCESS PRESSURE TRANSMITTER AND, PROCESSES TO MEASURE DIFFERENTIAL PRESSURE, AND FOR ERROR COMPENSATION IN THE MEASUREMENT OF DIFFERENTIAL PRESSURE, AND IN THE MEASUREMENT OF PROCESS PRESSURE". A device and process provide improved error compensation in the measurement of process pressure. The device and process are able to compensate for diaphragm deformation (displacement) and variable dielectric constants present in a process field environment. Pressure sensor 56, filled with a dielectric filling fluid 95 includes at least three capacitor plates 144, 146, 148, 150 placed around a diaphragm 102. At least two capacitor plates 144, 146 are placed on one side of a conductive diaphragm 102 and capacitor plate 148, 150 are placed on the other side of diaphragm 102. The process compensates for both the displacement of the diaphragm and the variance in the dielectric constant of the filling fluid 95. An error-compensated differential pressure measurement is a function of the amount of diaphragm deflection detected in the edge region 194 subtracted from the amount of diaphragm deflection detected in the central region 140. One way to measure diaphragm deflection is to measure changes in capacitances from two capacitors on each side of the diaphragm 102 and combine these values to achieve an error-compensated output representative of the applied differential pressure.