ABB 266 - Page 49

2600T Series Pressure transmitters | OI/266/FF/ADD-EN Rev. B 49
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:
– IN_1 is pressure – (t_1)
– IN_2 is temperature – (t_2)
– IN_3 is the compressibility factor Z – (t_3)
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 the
IN_3 a constant value Z or can be calculated by a pre-
vious block linked in the IN_3.
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
IN_3 as
Flow Compensation Approximate
Both IN_1 and IN_2 would be connected to the same
temperature
NOTE:
– The Square Root of the third power can be achieved
connecting the input to IN and IN_1.
– The Square Root of the fifth power can be achieved
connecting the input to IN, IN_1, IN_3.
OUT= {f · PV · GAIN + BIAS}
Where f = is limited
BTU Flow
– IN_1 is the inlet temperature
– IN_2 is the outlet temperature
OUT= {f · PV · GAIN + BIAS}
Where f = t_1 – t_2 is limited
Traditional Multiply Divide
OUT= {f · PV · GAIN + BIAS}
Where f = + t_3 is limited
Average
OUT= · GAIN + BIAS
f= number of inputs used in computation
Traditional Summer OUT= (PV + t_1 + t_2 + t_3) · GAIN + BIAS
Fourth Order Polynomial All inputs except IN_LO (not used) are linked together OUT= (PV + t_1
2
+ t_2
3
+ t_3
4
) · GAIN + BIAS
Simple HTG Compensated Level
– The PV is the tank base pressure
– IN_1 is the top pressure – (t_1)
– IN_2 is the density correction pressure – (t_2)
– GAIN is the height of the density tap
OUT= · GAIN + BIAS
Configuration hints
The minimum configuration for having the AR working and/or moving out from the OOS needs at least the following settings:
– Set ARITH_TYPE with a valid value. It must be different by 0 and in the range 1 – 9
– If the selected ARITH_TYPE is in the range between 1-5 (limited functions), the output limits COMP_HI_LIM > COMP_LO_LIM
– The BAL_TIME must be greater than the Block Execution Time
– When the ARITH_TYPE = 6 (Average) in case of no inputs available the output will be set to NaN (Not a Number)
– Set the GAIN with value different by 0
t_1
t_2
√
t_1
t_2 · t_3
√
t_1 · t_3
t_2
1
Z
√
t_1 · t_2 · t_3
2
PV – t_1
PV – t_2
t_1
t_2
PV + t_1 + t_2 + t_3
f