Commissioning Instructions
6
Siemens Industry, Inc.
A6V11668992
Restricted
2019-03-12
Excluding a box from the pressure reset system
It is possible to configure a Saturation signal (in ABT Site or online) to stay permanently
false (i.e., “Satisfied”). This allows a user to exclude a particular terminal from the
pressure reset system. This may be useful in situations where, for example, a certain box
is almost fully saturated but there is no actual need for pressure reset. See
Excluding_a_terminal_box for more information.
VAV Saturation using Central Functions
The AHU control program should adjust the supply duct pressure to achieve the lowest
pressure that fully satisfies the flow setpoint at each terminal. To accomplish this, the AHU
control program collects values indicating a saturated control loop from each assigned
terminal controller.
Each air terminal controller calculates a saturation signal that indicates whether the local
airflow control loop is operating close to the limit. The program in the Central Function
DXR counts the number of saturated airflow controllers among the terminals it serves.
VAV and FPB applications include a saturation function that calculates and determines
whether a configured box is operating above the configured limit. The saturation function
derives from the following objects and parameters:
Object and parameters for saturation
Name
Apogee Name
Description
Type
Default
VavSuAflStrtn
SU FLO SATUR
Supply air VAV airflow saturation (0:Satisfied; 1:Starved)
BCalcVal
Satisfied
EnStrtnCal
--
Enable saturation calculation (0:No; 1:Yes)
BCnfVal
Yes
StrtnLvl
--
Damper setting level indicating that the terminal is nearly fully open
ACnfVal
90%
DlyOnStrtn
--
Delay time before setting saturation signal
ACnfVal
60s
Object and parameters for airflow deviation calculation
Name
Apogee Name
Description
Type
Default
VavSuAirFlDvn
AIR VOL DIFF
Supply air VAV volume flow deviation
ACalcVal
0%
EnDvnCal
--
Enable deviation calculation (0:No; 1:Yes)
BCnfVal
Yes
AirFlErLm
--
Air volume flow error limit
ACnfVal
0%
Each VAV controller sends both an airflow deviation signal (AIR VOL DIFF) and a
saturation signal (SU FLO SATUR) to the Central Function application. SU FLO SATUR is a
binary object that indicates whether the box is open more than the configured saturation
level limit (StrtnLvl). AIR VOL DIFF is the VAV box airflow setpoint minus the actual VAV
box airflow.
EnStrtnCal allows the box to send the saturation calculation to the Central Function. When
set to No, the box will not be included in the collection of saturation levels but it will still be
a member of the Group.
All of these parameters that are part of the Supply air VAV application function have
counterparts that are unique to exhaust air as well. This means it is possible to
configure reset based on exhaust settings if desired.