Damping And Transmission Function; Damping; Transmission Function - ABB 2600T Series Operating Instruction

11.7 Damping and transmission function

11.7.1 Damping

If the output signal of the pressure transmitter is conditionally
irregular due to the process it can be electrically smoothed
(damped).
The additional time constant can be set in increments of
0.0001 seconds to a value between 0 and 60 seconds.
The damping has no influence whatsoever on the digitally
displayed measured value in the physical unit. It only acts on
the values that are derived from this, such as the analog
output current, the free process variable, the input signal for
the controller, etc.
The damping can be set locally via the LCD operating interface
(HMI), via the "Asset Vision Basic" software, or via a handheld
terminal.
58 OI/266CXX/266JXX/HART-EN Rev. B | 266CRx, 266JRx, 266CSx, 266JSx

11.7.2 Transmission function

In the evaluation of the output signal of the mulitvariable
transmitters, you must bear in mind that these devices can
work with different transmission functions.
For the 266Jxx the following can be set:
— Linear for measurements of differential pressure or fill level
— Square root (x) for flow measurements in accordance with
the differential pressure procedure with throttle elements
such as orifices, nozzles, Venturi / swirl tubes and similar
items
— Square root (x3) for flow measurements in open chutes
with rectangular or trapezoidal measurement weir
— Square root (x5) for flow measurements in open chutes
with V-measurement weir (triangular weir)
— Bidirectional for flow measurements with bidirectional
characteristic curve
— With customer-specific linearization table.
— For cylindrical, horizontal tanks
— For spherical tanks
These transmission functions can also be set for the 266Cxx
models, if the rake function is switched off.
For 266Cxx multivariable transmitters, set for mass flow
measurement, the following functions are possible:
— Square root (x) for differential pressure flow measuring
with throttle elements
— Bidirectional for flow measurements with bidirectional
characteristic curve
In addition, all characteristic curves are influenced by the
pressure-dependent and temperature-dependent status
correction.
For 266Cxx multivariable transmitters set for level
measurement, the following functions are possible:
— Linear
— With customer-specific linearization table
— For cylindrical, horizontal tanks
— For spherical tanks
Moreover, all characteristic curves are influenced by the
temperature-dependent, for drum water level measurement,
also pressure-dependent, density correction.
The output transmission functions can be activated via a
configuration tool (integral digital LCD display, handheld
terminal or PC software such as "Asset Vision Basic").