blockCHWIsoVal

Sequence of enable or disable chilled water isolation valve
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Information

Block updates chiller chilled water isolation valve enabling-disabling status when there is stage change command (uStaPro=true). It will also generate status to indicate if the valve reset process has finished. This development is based on ASHRAE Guideline 36-2021, section 5.20.4.16, item e, and section 5.20.4.17, item c, which specifies when and how the isolation valve should be controlled when it is in the stage changing process.

  • When there is the stage up command (uStaPro=true) and next chiller head pressure control has been enabled (uUpsDevSta=true), the chilled water isolation valve of the next enabling chiller indicated by nexChaChi will be enabled.
  • When there is the stage down command (uStaPro=true) and the disabling chiller (nexChaChi) has been shut off (uUpsDevSta=true), the chiller's isolation valve will be disabled.

The valve should open or close slowly. The valve time chaChiWatIsoTim should be determined in the field.

This sequence will generate array y1ChiWatIsoVal, which indicates chilled water isolation valve position command. yChaChiWatIsoVal will be true when all the enabled valves are fully open and all the disabled valves are fully closed.

Parameters

TypeNameDefaultDescription
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.ActuatorvalTypBuildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.Actuator.ModulatingChiller CHW isolation valve type
Booleanhave_twoPosEndSwifalseTrue for chiller CHW isolation valves with end switch status feedback
IntegernChi2Total number of chiller, which is also the total number of chilled water isolation valve
RealchaChiWatIsoTim0Time to slowly change isolation valve, should be determined in the field
Advanced
Booleanis_inUpEndfalseTrue: it is used in the up ending process

Connectors

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Interfaces.IntegerInputnexChaChiIndex of next chiller that should change status
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nChi]uChiChiller status: true=ON
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nChi]u1ChiWatIsoValOpeChiller chilled water isolation valve open end switch. True: the valve is fully open
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput[nChi]u1ChiWatIsoValCloChiller chilled water isolation valve close end switch. True: the valve is fully closed
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputuUpsDevStaStatus of resetting status of device before enabling or disabling isolation valve
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputuStaProIndicate if there is a stage up or stage down command
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput[nChi]y1ChiWatIsoValChiller chilled water isolation valve command
Buildings.Controls.OBC.CDL.Interfaces.RealOutput[nChi]yChiWatIsoValChiller chilled water isolation valve position setpoint
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutputyChaChiWatIsoValStatus of chilled water isolation valve control: true=completed change of the isolation valve position

Revisions

  • February 4, 2020, by Jianjun Hu:
    First implementation.