Addendum For Differential Pressure Transmitters: Selectable Output Functions - ABB 268D/V Operating Instruction

ADDENDUM FOR DIFFERENTIAL PRESSURE TRANSMITTERS:
SELECTABLE OUTPUT FUNCTIONS
GENERAL DESCRIPTION
The 2600T Series Differential Pressure Transmitter provides a selection of output functions, as follows:
Linear
Sq. Root (x)
3
Sq. Root (x
Sq. Root (x 5
Polynomial
Costant current
where |x| and output are in the range 0 to 1 (0% to 100%).
Figure 1 shows the Input/output relationships with the different Square Root Options applied.
These output functions can be activated using a Configuration Tool like the Hand Held Communicator, a HART Universal
Communicator or a Personal Computer, carrying the Smart Configuration Program, connected to the transmitter via a Bell 202
modem (see the relevant Operating Instructions).
The output of the transmitter is actually the analog signal 4 to 20 mA and the digital signal read in engineering units on the integral
display.
Flow %/100
0.9
for differential pressure or level measurements
for flow measurements using restriction type primary element, like orifice plate,
integral orifice, Venturi or Dall tube and similar.
) for open channel flow measurements using rectangular or trapezoidal weir
) for open channel flow measurements using V-notch (triangular) weir.
for input linearization using a 5th-order polynomial function
for input linearization using 2 polynomial functions of 2nd order
for loop or associated equipment test.
1
0.8
Sq.Root x
0.7
0.6
Sq.Root x^3
0.5
0.4
0.3
0.2
0.1
0
0 0.1 0.2 0.3
Differential Pressure %/100
Sq.Root x^5
0.4 0.5 0.6 0.7 0.8
Fig. 1
0.9 1
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