Operation; The Sensor Cell - Emerson Rosemount 2151N Reference Manual

Rosemount 2151N
Figure 4-1 – Block Diagram

THE SENSOR CELL

43
Process pressure is transmitted through an isolating
diaphragm and silicone oil fill fluid to a sensing diaphragm in
the center of the Sensor. The reference pressure is
transmitted in a like manner to the other side of the sensing
diaphragm. The capacitance plates on both sides of the
sensing diaphragm detect the position of the sensing
diaphragm. The capacitance between the sensing diaphragm
and either capacitor plate ranges from 40 pf to 80 pf
depending on input pressure. An oscillator drives the sensor
current through the transformer windings at roughly 110 kHz
and 20 V .
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Reference Manual
00809-0000-4851 Rev AD
December 2023

Operation