[Vav21] Variable air volume, external control
Program block, name / node subtype: [Vav21] Variable air volume, external control
Library hierarchy: Ventilation and air conditioning equipment
Family: Vav
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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 a VAV damper with external control.
Sends a relative setpoint (in %) for the air volume flow to the VAV damper.
External control (from the point of view of the PXC4/5/7): The VAV damper has its own control unit and the volume flow control of the control unit of the damper. It measures the volume flow and modulates a damper position to control the air volume flow.
The nominal air volume flow must be set (via analog configuration value). An analog calculated value shows the absolute setpoint (in m3/h) for the air volume flow.
This program block has the following optional functions:
Option: Air volume flow (1xAI)
Reads and displays the current air volume flow from the control unit of the VAV damper. A calculated value shows an air volume flow deviation (percentage of undersupply that indicates that the air volume flow cannot reach the setpoint even if the damper is fully open).
Option: Close command (1xBO)
Forces the VAV damper to close (and not to stay at minimum air volume flow when there is no setpoint, if it is configured in that way).
Option: Max. air volume flow command (1xBO)
Forces the VAV damper to go to the maximum air volume flow.
Option: Minimum air volume flow
Configuration for a minimal air volume flow (in m3/h) that is sent to the VAV damper.
Option: Position feedback (1xAI)
Reads the position of the damper.
Name | Description | Type | Alarm / Notification class | Trend / Type | |
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SpAirFlRel | Setpoint for relative air volume flow | AO: Analog output | No | No | |
SpAirFl | Setpoint for air volume flow | ACalcVal: Analog calculated value | No | No | |
AirFlNom | Nominal air volume flow | ACnfVal: Analog configuration value | No | Yes, 4 | |
Name | Description | Type | Alarm / Notification class | Trend / Type | |
|---|---|---|---|---|---|
AirFlMin | Minimum air volume flow | ACnfVal: Analog configuration value | No | Yes, 4 | |
AirFl | Air volume flow | AI: Analog input | No | Yes, 2 | |
Further elements that belong to this element: AirFlDvn | Air volume flow deviation | ACalcVal: Analog calculated value | |||||
FbPos | Position feedback | AI: Analog input | No | Yes, 2 | |
ClsCmd | Close command | BO: Binary output | No | Yes, 4 | |
Description |
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Air flow maximum command Elements that belong to this option: Open command | BO: Binary output |