blockFailsafeCondition
Failsafe condition used in staging up and down
Information
Failsafe condition used in staging up and down, implemented according to the specification provided in section 5.20.4.15 of Guideline 36-2021. The subsequence applies to primary-only plants with and without a WSE. The sequence contains a boolean flag to differentiate between parallel and series chiller plants.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_serChi | false | true = series chillers plant; false = parallel chillers plant |
| Boolean | have_senDpChiWatRemWir | true | True=remote DP sensor hardwired to controller |
| Integer | nRemSen | 2 | Total number of remote differential pressure sensors |
| Real | faiSafTruDelay | 900 | Enable delay |
| Real | TDif | 1 | Offset between the chilled water supply temperature and its setpoint |
| Real | TDifHys | 1 | Temperature hysteresis deadband |
| Real | dpDif | 2*6895 | Offset between the chilled water differential pressure and its setpoint |
| Real | dpDifHys | 0.5*6895 | Pressure difference hysteresis deadband |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TChiWatSupSet | Chilled water supply temperature setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TChiWatSup | Chilled water supply temperature | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | dpChiWatSet_local | Chilled water local differential pressure setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | dpChiWat_local | Chilled water differential pressure from local pressure sensor | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput[nRemSen] | dpChiWatSet_remote | Chilled water remote differential pressure setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput[nRemSen] | dpChiWat_remote | Chilled water differential pressure from remote sensor | |
| Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput | y | Failsafe condition for chiller staging |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Reals.Hysteresis | hysdpSup | Checks how closely the chilled water pump differential pressure aproaches its setpoint from below | |
| Buildings.Controls.OBC.CDL.Reals.Hysteresis | hysTSup | Checks if the chilled water supply temperature is higher than its setpoint plus an offset | |
| Buildings.Controls.OBC.CDL.Reals.Hysteresis[nRemSen] | hysdpSup1 | Checks how closely the chilled water pump differential pressure aproaches its setpoint from below |
Revisions
-
January 21, 2019, by Milica Grahovac:
First implementation.