[AhuHuCtl21] Sensors, setpoints and humidity control for air handling unit
Program block, name / node subtype: [AhuHuCtl21] Sensors, setpoints and humidity control for air handling unit
Library hierarchy: Ventilation and air conditioning equipment
Family: AhuHuCtl
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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.
Performs humidity control (and/or limits the setpoints for supply humidity control) and contains the setpoints for humidification and dehumidification and the humidity sensors.
Cascade control for the extract air humidity control (HuCasCtr21) or supply air humidity control (HuSuCtr21) are supported and can be configured (alternatively).
The cascade control works in the following way: Setpoints for humidification and dehumidification (in %rH) are provided to the cascade controller in HuCasCtr21 that issues setpoints for the supply air humidity (in g/kg) to the humidifier and to the cooling coil (or heating/cooling coil). Their controllers control the supply air absolute humidity and have optional limitation controllers for the supply air relative humidity.
In case of cascade control, it is important to use HuCtr21 (humidity controller absolute) in the humidifier and in the cooling coil (or heating/cooling coil).
The supply humidity control works in the following way: Setpoints for humidification and dehumidification (in %rH) are sent through HuSuCtr21 and it issues setpoints for the supply air humidity (in %rH) to the humidifier and to the cooling coil (or heating/cooling coil). Their controllers control the supply air relative humidity.
In case of supply air humidity control, it is important to use HuCtr22 (humidity controller for relative) in the humidifier and in the cooling coil (or heating/cooling coil).
The setpoints for humidification and dehumidification are preset for extract/room air humidity cascade control. In case of supply air humidity control, the setpoints for humidification and dehumidification should be set closer to each other with a narrow zero energy band.
A parameter in the program defines the influence on the plant behavior of an alarm or fault of the supply air humidity sensor. It is preset in such a way that the plant does not switch off in the event of an alarm or fault.
This program block has the following optional functions:
Option: Outside air humidity (1xAI)
Creates an outside air humidity.
Option: Room air humidity (1xAI)
Creates a room air humidity.
The room air humidity can be used for cascade control. This needs a small change in the program.
Name | Description | Type | Alarm / Notification class | Trend / Type |
|---|---|---|---|---|
HuSu | Supply air humidity | AI: Analog input | No | Yes, 1 |
HuEx | Extract air humidity | AI: Analog input | No | Yes, 1 |
SpDhu | Setpoint for dehumidification | AI: Analog input | No | Yes, 4 |
SpHum | Setpoint for humidification | AI: Analog input | No | Yes, 4 |
HuCtl | Humidity control | N/A | N/A |
Name | Description | Type | Alarm / Notification class | Trend / Type |
|---|---|---|---|---|
HuOa | Outside air humidity | AI: Analog input | No | Yes, 3 |
HuR | Room air humidity | AI: Analog input | No | Yes, 3 |