Application

Sequence of Operation
Open Loop (Mode 3)
27
Siemens Industry, Inc.
BACnet LCM-OAVS, App 2924
140-1304
2015-07-07
Example 3 - Table with Voltage End Limits and Low Flow Value – direct acting
Point
Flow
Volt
1
300
7.0
2
0
10.0
3
0
10.0
15
0
10.0
16
1200
0.0
Example 4 - Table with Voltage End Limits and Low Flow Value – reverse acting
You can also manually populate the table with additional values as shown in Example
5 below. In this case, the table becomes indistinguishable from a table generated using
the calibration process.
Point
Flow
Volt
1
300
3.0
2
0
0
7
0
0
8
340
3.2
9
390
3.5
10
521
3.8
11
531
4.1
12
598
4.9
13
691
5.8
14
798
7.0
15
0
0
16
1200
10
Example 5 - Multi-point Table
The point values above are for the exhaust table. Open loop supply operation is
similar, but the points used are 1 through 16; not 30 through 46.
Since the actual airflow being measured is 0, the heating safety requirement for
minimum airflow is not met and heating will not occur. To re-enable heating, the FLO
value must be set to 0, but only after a thorough safety review that the electric heating
mechanism has sufficient internal safeguards (that is, resettable shutoffs) that would
operate in the event that the system at some time actually did have insufficient flow.
NOTE:
Since
PID Only Mode uses PID without a Venturi table and Open Loop Mode uses
Venturi table without PID, these two modes cannot be used at the same time.