Chapter Objectives
This chapter will help you understand why signal conditioning is required in
process control and to familiarize you with signal conditioning methods.
The following are covered in this chapter:
The conversion of sensor signals into pneumatic or electrical signals
Signal linearization, methods of setting signal zero level, and span
Nonlinear analog amplifiers
Digital linearization
The difference between sensors, transducers, and converters
Conditioning for local displays and transmission
Temperature compensation used in signal conditioning
Signal conditioning used with Hall effect and magneto resistive element
(MRE) devices
Considerations using capacitive devices
Resistance temperature detectors (RTD) signal conditioning
Many sensors do not have a linear relationship between the physical variable
and the output signal. Output signals need to be corrected for the nonlinearity in
their characteristic, or conditioned for transmission to a central controller, or for
direct control, so that the necessary valves or actuators can be operated to accurately
correct for variations in the measured variable in a process control system.