[StupPrg21] Startup function purge
Program block, name / node subtype: [StupPrg21] Startup function purge
Library hierarchy: Ventilation and air conditioning functions
Family: StupPrg
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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.
It is usually used in an air handling unit. It prevents the preheater frost protection from responding when the plant is started in cold outdoor conditions and ensures that the water in the preheater is warm.
Usually, this function is the first element of the starting sequence of an air handling unit and holds it until the function returns a signal that the purging phase is complete.
A binary calculated value indicates that the purge phase is active.
This program block has the following optional functions:
Option: Stop purge in case of return temperature increase
If the return temperature reaches a certain value, e.g., 30 °C, during the purge phase, then the signal indicating that the purge phase is complete is generated before the purge time has elapsed.
The function block PURGE is only used to activate the purge functionality, if TOa < PURGE.TOaLoLm and the plant was off for a period longer than TiOffMin (typically 15 minutes). PURGE.TiPrgMax and PURGE.TiPrgMin can be the same, since the time for having warm water in the preheater depends only on the hydraulics of the plant (pipe length and connection type) and not on the outside temperature.
Name | Description | Type | Alarm / Notification class | Trend / Type | |
|---|---|---|---|---|---|
StupPrgActv | Startup purge active | BCalcVal: Binary calculated value | No | No | |
Purge | Purge | N/A | N/A | N/A | |
Description |
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Stop purge upon return temperature increase |
The function block PURGE is only used to activate the purge functionality, if TOa < PURGE.TOaLoLmand and the plant was off for a period longer than TiOffMin (typically 15 minutes).
PURGE.TiPrgMax and PURGE.TiPrgMin could be the same, since the time for having warm water in the coil depends only on the plant's hydraulics (pipe length and connection type) and not on the outside temperature.