2600T SERIES | PRESSURE TRANSMITTERS | OI/266/FF-EN REV. E
95
If the status of IN_LO is unusable and IN is usable and greater than RANGE_LO, then g should be set to one. If the status of IN is
unusable, and IN_LO is usable and less than RANGE_HI, then g should be set to zero. In each case the PV should have a status of
Good until the condition no longer applies. Otherwise, the status of IN_LO is used for the PV if g is less than 0.5, while IN is used for
g greater than or equal to 0.5. An optional internal hysteresis may be used to calculate the status switching point.
Six constants are used for the three auxiliary inputs. Each has a BIAS_IN_i and a GAIN_IN_i. The output has a BIAS and a GAIN static
constant. For the inputs, the bias is added and the gain is applied to the sum. The result is an internal value called t_i in the function
equations. The equation for each auxiliary input is the following:
t_i = (IN_i + BIAS_IN_i) * GAIN_IN_i
The flow compensation functions have limits on the amount of compensation applied to the PV, to assure graceful degradation if
an auxiliary input is unstable. The internal limited value is f.
Equations
Algorythm type Description Function
Flow Compensation Linear Used for density compensation of Volume flow
OUT= {f · PV · GAIN + BIAS}
Where f = is limited
Flow Compensation Square Root
Usually:
OUT= {f · PV · GAIN + BIAS}
Where f = for Volumetric Flow is limited
For the calculation of the Volumetric Flow t_3 = Z
The compressibility factor Z can be set writing into
Z or can be calculated by a
OUT= {f · PV · GAIN + BIAS}
Where f = for Volumetric Flow is limited
In case it would be necessary produce the Mass Flow,
the compressibility factor Z must be set as into the
Flow Compensation Approximate
temperature
NOTE:
– The Square Root of the third power can be achieved
– The Square Root of the fifth power can be achieved
OUT= {f · PV · GAIN + BIAS}
Where f = is limited
BTU Flow
OUT= {f · PV · GAIN + BIAS}
Traditional Multiply Divide
OUT= {f · PV · GAIN + BIAS}
Average
OUT= · GAIN + BIAS
f= number of inputs used in computation
Traditional Summer OUT=
Fourth Order Polynomial All inputs except IN_LO (not used) are linked together OUT=
) · GAIN + BIAS
Simple HTG Compensated Level
– The PV is the tank base pressure
– GAIN is the height of the density tap
OUT= · GAIN + BIAS
t_1
t_2
√
t_1
t_2 · t_3
√
t_1 · t_3
t_2
√
t_1 · t_2 · t_3
2
t_1
t_2
f
PV – t_1
PV – t_2
1
Z
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