[DmpMx21] Mixed air damper, temperature-controlled
Program block, name / node subtype: [DmpMx21] Mixed air damper, temperature-controlled
Library hierarchy: Ventilation and air conditioning equipment
Family: DmpMx
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Configurator
Program blocks are stored in the library without I/Os. Use the auto-create and auto-connect functions to create I/Os and/or to connect them to the interface blocks, e.g., R_A, CMD_B. Alternatively, take the I/Os from the folder containing the predefined I/Os in the library and/or from the plant and connect them to the interface blocks.
Controls the position of the damper for recirculated air (and the positions of the optional exhaust and outside air dampers) to support the air quality control (with a controller in another program block) or to perform supply air temperature control (optionally).
There is a configuration value for setting up a minimum position for outside air.
The signal from an air quality controller from another program block has priority over the signal from its temperature controller. If it needs to be the other way around, change the existing MAX8_R in the program to MIN8_R.
This program block has the following optional functions:
Option: Exhaust air damper (1xAO, 1xAI)
Controls the position of the exhaust air damper (Dmp24).
Option: Outside air damper (1xAO, 1xAI)
Controls the position of the exhaust air damper (Dmp24).
Option: After purge, start with 100 % for a configured time
Provides an interface to the state of the "Start-up purge" function and logic to keep the recirculated air damper and the other two optional dampers at the position for minimum position for outside air for a configurable time, e.g., 4 minutes, after the "Start-up purge" function has finished.
Option: Disable temperature control in case of dehumidification
Provides an interface (most likely to the cooling coil) and logic to disable the temperature control in case of dehumidification to not preheat the air when the cooling coil performs dehumidification.
Delete this option if this coil is used as a reheater.
Option: Fire detection contact
Provides an interface "Fire detection contact" (most likely in the plant operating mode of an air handling unit plant) and logic to close all dampers.
Option: Generate disturbance signal switching off the plant at very low outside temperature
In case of a problem with the mixed air dampers at very low outside temperature, the power of the heating coil could be insufficient, and the resulting supply air temperature could drop to a level that is above the frost protection but is still very unpleasant. Therefore, a disturbance signal that switches off the air handling unit plant is generated.
Option: Temperature controller
A PID controller and logic for supply air temperature control.
The temperature controller changes its control action dynamically for heating-based or cooling-based conditions from another program block.
Name | Description | Type | Alarm / Notification class | Trend / Type |
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PosOaMin | Minimum position for outside air | ACnfVal: Analog configuration value | No | No |
DmpRc | Recirculated air damper | N/A | N/A |
Name | Description | Type | Alarm / Notification class | Trend / Type |
|---|---|---|---|---|
DmpOa | Outside air damper | N/A | N/A | |
DmpEh | Exhaust air damper | N/A | N/A | |
TCtr | Temperature controller | Ctr: Controller | N/A | N/A |
Description |
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After purge start with 100 % for a configured time. |
Generate disturbance signal that switches off the plant at very low outside temperature. |
Disable temperature control in case of dehumidification |
Fire detection contact |
The option "Fire detection contact" reads the status of the fire detection contact of the plant and closes all 3 dampers with higher priority.