Extraction arm, pressure sensor and duct area (ExtrcEqp12)
| This application function monitors a pressure sensor on an analog input object (ExtrcDiffP) and calculates the air flow through the extraction arm using a data model with a duct area value. The AF works with or without a binary input (ExtrcSpSel) to select the air flow setpoint. If a binary input is not connected, the setpoint will always equal ExtrcSp1. If a binary input is connected, the setpoint will equal ExtrcSp1 when the BI is active, and it will equal ExtrcSp2 when the BI is inactive. |
Required elements and how to configure them:
Element | I/O | Signal type |
|---|---|---|
ExtrcDiffP "Extraction differential pressure" | On-board output, Extraction differential pressure | 0…10V |
(Optional) | On-board output, Extraction setpoint selector | Binary input |
Function
The AF functions as described above. The main output signals are calculated values for Extraction effective air velocity, Extraction present setpoint, and Extraction air volume flow.
Main features:
- Analog input pressure sensor monitor
- Setpoints for extract airflow, configurable
- Failure mode (configurable) for air volume flow sensor
- Trend for extraction present setpoint
- Trend for extraction air volume flow
- Event enrollment for Monitoring for extraction air volume flow
Configuration
Objects
Description | Object | Type | Default value |
|---|---|---|---|
Extraction duct area | ExtrcDuctArea | ACnfVal | 0.05 [m2] |
Extraction duct shape | ExtrcDuctShape | MCnfVal | Round |
Extraction dimension A | ExtrcDmsnA | ACnfVal | 20 [cm] |
Extraction dimension B | ExtrcDmsnB | ACnfVal | 20 [cm] |
Extraction flow coefficient | ExtrcFlCoef | ACnfVal | 1 |
Extraction setpoint 1 | ExtrcSp1 | ACnfVal | 0 |
Extraction setpoint 2 | ExtrcSp2 | ACnfVal | 0 |
Extraction setpoint 3 (not used) | ExtrcSp3 (not used) |
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Configuration
Parameters
Description | Parameter | Default value |
|---|---|---|
Enable propagation air volume flow failure Determines whether the system receives updates from the digital pressure sensor about airflow failures. If set to "No," the system assumes that the airflow is valid. Refer to the room pressure control application failure response and configuration. | EnPrpgAflFail | No |
Switch-on point for differential pressure Sets a minimum threshold for which the differential pressure sensor will show a measurement. Below this threshold, the measured value will be 0. Note that the sensor will continue to show a measurement for as long as it remains above the value determined by HysDiffP. See HysDiffP for examples. | SwiOnPtDiffP | 0.2 Pa 0.001 [inWC] |
Hysteresis for differential pressure Hysteresis for differential pressure. Related to the Switch-on point for differential pressure (SwiOnPtDiffP). Once the system reaches the switch-on point, the differential pressure sensor returns a non-zero value. After differential pressure passes above SwiOnPtDiff, the HysDiffP parameter sets how far the pressure measurement can fall below the switch-on point (SwiOnPtDiff), and still return a non-zero value. Note that the differential pressure measurement must first pass above the value set by SwiOnPtDiff before HysDiffP becomes active. This parameter must be in units compatible with SwiOnPtDiffP | HysDiffP | 0.1 Pa 0.000 [inWC] |
Time constant for air volume flow The time constant for the attenuation filter on the air volume flow sensor. Larger values help to stabilize fluctuating air volume flow sensor values. Larger values for this constant also cause the values reported by the air volume flow sensor to be more heavily weighted toward measurements in the past. Leaving at 0 disables the filter. | TiConAirFl | 0 [s] |
Switch delay for tracking method to air volume flow If the tracking method switches from the setpoint to airflow (see SwiTolTckMthd), this sets the amount of time to wait before making the switch. | SwiDlyTckMthd | 6000 [s] |
Switch tolerance for tracking method to air volume flow Sets an acceptable level of difference (percentage) between the relative airflow setpoint and current relative airflow. By default, the system tracking method follows the airflow setpoint. But if current relative airflow deviates from the relative setpoint by a percentage amount greater than what is set by the SwiTolTckMthd parameter, the system switches from tracking to the setpoint to tracking to the actual airflow. Setting the tolerance level (SwiTolTckMthd) to 100% will not always prevent tracking from switching from setpoint to airflow. | SwiTolTckMthd | 5 [%] |
Nominal air volume flow Represents the maximum expected airflow value when the damper is all the way open. To help normalize the airflow and the airflow setpoint for control purposes, the system will always pick the highest between AirFlNom and any other airflow configuration values. | AirFlNom | 0 [m3/h] 0 [ft3/min] 0 [l/s] |
Pressure unit | PUnit |
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Air volume flow unit | AirFlUnit |
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Interface
Interface | Description | Type | Ref. | Owned by |
|---|---|---|---|---|
ExtrcSpSel | Extraction setpoint selector | BI | ◉ | Room segment / Field device |
ExtrcDiffP | Extraction differential pressure | AI | ◉ | Room segment / Field device |
ExtrcAirVEff | Extraction effective air velocity | ACalcVal | ● | - |
ExtrcPrSp | Extraction present setpoint | ACalcVal | ● | - |
TrndExtrcPrSp | Trend for extraction present setpoint | FtrSel | ● | - |
ExtrcAirFl | Extraction air volume flow | ACalcVal | ● | - |
TrndExtrcAirFl | Trend for extraction air volume flow | FtrSel | ● | - |
ExtrcAirFlMon | Monitoring for extraction air vol.flow | FtrSel | ● | - |
ExtrcDuctArea | Extraction duct area | ACnfVal | ● | - |
ExtrcDuctShape | Extraction duct shape | MCnfVal | ● | - |
ExtrcDmsnA | Extraction dimension A | ACnfVal | ● | - |
ExtrcDmsnB | Extraction dimension B | ACnfVal | ● | - |
ExtrcFlCoef | Extraction flow coefficient | ACnfVal | ● | - |
ExtrcSp1 | Extraction setpoint 1 | ACnfVal | ● | - |
ExtrcSp2 | Extraction setpoint 2 | ACnfVal | ● | - |
ExtrcSp3 (not used) | Extraction setpoint 3 (not used) |
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