Application

Sequence of Operation
Wiring Diagrams
39
Siemens Industry, Inc.
Application Note, App 6750
140-1328
2015-07-07
The application varies the supply airflow as the fume hood flow changes, in order to
maintain the proper room pressurization. The supply airflow is not varied for cooling
purposes; all temperature control is done by the reheat valve.
Operating Without a Supply Box
This application can operate without a supply box. If a supply box is not being
controlled, set TRACK METHOD to FLOW and set the following points:
 TRACK MODE to 3.
(a value of 3 = ETS Flow Tracking, should be used for both the occupied and
unoccupied modes).
 SUP FLO COEF to 0.
When SUP FLO COEF equals 0, SUP AIR VOL will always read 0, but will never
show as Failed.
 OCC SUP MIN and UOC SUP MIN to 0.
If these two points are not set to 0, SUP AIR VOL— will read 0 since SUP FLO
COEF was set to 0—will be less than the supply box minimum, resulting in a false
ventilation alarm.
This setup is useful when the room has a constant source of supply air from other
equipment or sources not connected to the controller. If you enter this constant supply
air volume value into OTHER SUP, the application will vary the general exhaust airflow
as the fume hood flow changes, in order to maintain the proper room pressurization.
Since all temperature control will be done by the reheat valve, START should be set to
100 to allow the reheat valve to be controlled by the full range of TEMP LOOPOUT and
to prevent the room temperature PID Loop from winding up.
Wiring Diagrams
Offboard Air Module Wiring.
CAUTION
The LCM-OAVS has two terminal blocks with terminations numbered identically
(terminations 1 through 16). DO NOT mix these up with each other.
If the LCM-OAVS is not connected as shown, it is not resistant to electrical surges. It
is also susceptible to interference from other equipment.
CAUTION
A separate power supply is required if a 4-20 mA sensor is used.
Failure to follow wiring precautions will result in equipment damage.