blockLocalDp_setpoint
Pump speed control for primary-only plants where the remote DP sensor(s) is not hardwired to the plant controller, but a local DP sensor is hardwired
Information
Block that calculates the local DP setpoint for the local primary loop DP sensor
hardwired to the plant controller. It is applicable for the primary-only plants where
the remote pressure differential (DP) sensor(s) are not hardwired to the plant controller,
but a local DP sensor is hardwired to the plant controller,
according to ASHRAE Guideline 36-2021,
section 5.20.6 Primary chilled water pumps, part 5.20.6.10.
-
Remote DP shall be maintained at setpoint
dpChiWatSet by a reverse-acting
PID loop running in the controller to which the remote sensor is wired.
The loop output shall be a DP setpoint for the local primary loop DP sensor
hardwired to the plant controller. Reset local DP from minLocDp,
e.g., 5 psi (34473.8 Pa), at 0% loop output to maxLocDp at 100%
loop output.
Parameters
| Type | Name | Default | Description |
|---|
| Integer | nSen | 2 | Total number of remote differential pressure sensors |
| Integer | nPum | 2 | Total number of chilled water pumps |
| Real | minLocDp | 5*6894.75 | Minimum chilled water loop local differential pressure setpoint |
| Real | maxLocDp | 15*6894.75 | Maximum chilled water loop local differential pressure setpoint |
| Pressure controller |
| Buildings.Controls.OBC.CDL.Types.SimpleController | controllerType | Buildings.Controls.OBC.CDL.Types.SimpleController.PI | Type of controller |
| Real | k | 1 | Gain of controller |
| Real | Ti | 0.5 | Time constant of integrator block |
| Real | Td | 0.1 | Time constant of derivative block |
Revisions
-
August 1, 2019, by Jianjun Hu:
First implementation.
