Rockwell Automation T8019 Trusted Process Control Algorithm Software Package - Manual (Page 11)

Trusted
TM
Process Control Algorithms T8019
Issue 8 Sep 07 PD-T8019 11
1.5. Drum Level Control
PC_DRUM
OUT
PP
LV
This function is to provide the pressure compensated drum level. PP is the differential pressure, and
LV is the level in percentage of full-scale, the output (OUT) is return as a value 0 to 100%. PP, LV and
OUT are all of type REAL. The function additionally to compensates for the reverse acting output of the
level input (increasing PP value of decreasing differential pressure).
( )
( )
P 10 0.173 0.88
LV P 10 5.43 101
OUT
3
3
Ч Ч
Ч Ч
=
Underflow, overflow and divide by zero error conditions are to result in value of zero being returned and
the corresponding error counter incremented.
1.6. Mass Flow Computation
Error! Objects cannot be created from editing field codes.
The mass-flow computation block provides the mass flow corrected for the current operating
conditions.
( ) ( )
( )
+
+
Ч Ч Ч Ч Ч Ч =
273 T
14.7 P
h e m Z C OUT
PP is the differential pressure, P is pressure and T is temperature. C, Z, m, e and h are intended to be
constant values. All parameters are of type REAL.
PP and P are in psi, T is in 0 C.
If T=-273, a divide by zero error condition is generated, this is to increment the associated error
counter and the mass flow function is to return a value of -1. Over and underflow conditions are to
result in an output value of -1 and increment the associated error counter.