Fujimoto Fuji Differential Pressure Transmitter FKK 4 - Manual (Page 7)

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OUTLINE
The FCX-CII series transmitter detects the differential pressure or pressure of various
fluids, converts it into a current signal of 4 to 20 mA DC and transmits it.
All the adjustment functions are incorporated in the transmission unit for making
adjustments easily and exactly.
Transmitter settings (such as range and damping time constant, etc.) can be changed from
an HHC (Hand Held Communicator).
Principle
The operating principle of the FCX-CII series transmitter is shown in the block
diagram below.
The input pressure is changed into an electrostatic capacitance in the detecting unit.
The change proportional to the pressure undergoes conditioning and amplification in
the transmission unit, and is then output as a current of 4 to 20mA DC.
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Displacement
Sensor
Input
differential
pressure
Detecting unit
Transmission unit
Operational
amplification
circuit
Output
current
Diaphragm
Measuring
circuit
Capacitance
change