78
2. Depending on the setting of sub-menu 4-9 the unit will either shutdown or the compressors will be inhibited when
the alarm is activated.
3. Unit will return to normal operation when this alarm is corrected.
FAN SPEED CONTROL FOR CHILLED WATER (CW) UNITS WITH PLUG FANS
Four (4) fan speed control modes can be selected for units with plug fans. The control modes are accessible through
Menu Group 3, Sub-Menu 3-21. Any one of the following may be chosen:
1. CONSTANT FAN SPEED
2. CONSTANT STATIC PRESSURE
3. PROPORTIONAL FAN SPEED CONTROL BASED ON THE CW VALVE ACTION
4. FAN SPEED CONTROLLED BY BMS
1. CONSTANT FAN SPEED: On units where constant design fan speed is required (i.e. standard plug fan confi guration),
a value based on percentage of fan speed is entered into the DAP-III through Sub-Menu 3-19 (CONSTANT FAN SPEED
FOR CW COOLING). The adjustable range is 60 – 100%, which results in an analog output of 6 VDC to 10 VDC. In
this mode the fan will start and operate at the selected fan speed. In addition, Sub-Menu 3-21 (FAN SPEED CONTROL
FOR CW COOLING) must be set to “CONSTANT SPEED”.
2. CONSTANT STATIC PRESSURE CONTROL MODE – Both an optional analog module and differential pressure
transmitter are required for this mode. The following Sub-Menus must be confi gured for this mode to operate:
Sub-Menu
3-19 CONSTANT FAN SPEED FOR CW COOLING
Sub-Menu
3-21 FAN SPEED CONTROL FOR CW COOLING
Sub-menu
3-22 MAXIMUM FAN SPEED
Sub-Menu
3-23 MINIMUM FAN SPEED
Sub-Menu
3-24 DIFFERENTIAL PRESSURE SETPOINT
Sub-Menu
3-25 DIFFERENTIAL PRESSURE DEADBAND
Sub-menu
3-26 FAN SPEED RESPONSE RATE
The differential pressure (DP) transducer will be connected to the DAP-III analog module to report the differential
pressure across the unit (between the supply and return section). Three fan speeds need to be programmed via the
DAP-III menus: CONSTANT FAN SPEED FOR CW COOLING (Sub-Menu 3-19), MAXIMUM FAN SPEED (Sub-Menu
3-22) and MINIMUMU FAN SPEED (Sub-Menu 3-23).
When started in the mode, the fan will fi rst operate at the programmed constant fan speed for 5 minutes. After the initial
5 minutes, the fan will proportionally increase or decrease the speed to maintain a constant static pressure setpoint as
follows:
•
If the measured differential pressure is less than the differential pressure setpoint minus the differential pressure
deadband, the fan speed will increase 1% for each response time period until the differential pressure setpoint is
reached (fan speed cannot exceed the maximum speed).
•
If the measured differential pressure is greater than the differential pressure setpoint plus differential pressure
deadband, the fan speed will decrease 1% for each response time period until the differential pressure setpoint is
reached (fan speed cannot be lower than minimum fan speed).
•
Otherwise, fan speed will remain constant
3. PROPORTIONAL FAN SPEED CONTROL BASED ON THE CW ACTION MODE – Units where proportional fan
speed control based on the CW valve action is required, a maximum allowable fan speed (range 70 – 100% of fan
capability) is programmed on Sub-Menu 3-22 (MAXIMUM FAN SPEED) and a minimum fan speed (as low as 40% of
the maximum allowable fan speed) is entered through the DAP-III (Sub-Menu 3-23, MINIMUM FAN SPEED). In this
mode, Sub-Menu 3-21 (FAN SPEED CONTROL FOR CW COOLING) must be set to (“PROPORTIONAL TO VALVE”).
Содержание DAP III
Страница 2: ......
Страница 92: ...92 gForce Terminal Strip ...
Страница 93: ...93 Remote DAP III Display Mount connection to Control Module ...
