blockOverrides

Software switches to override setpoints
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Information

This block considers the overrides to the setpoints for series fan-powered unit with constant-volume fan. The implementation is according to the Section 5.9.7 of ASHRAE Guideline 36, May 2020.

Provide software switches that interlock to a system-level point to:

  1. when oveDamPos equals to 1, force the damper to full closed by setting yDam to 0,
  2. when oveDamPos equals to 2, force the damper to full open by setting yDam to 1.
  3. when uHeaOff equals to true, force the heating valve to full closed by setting yVal to 0.
  4. When oveFan equals to 1, force the fan to turn OFF.
  5. When oveFan equals to 2, force the fan to turn ON.

Connectors

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Interfaces.IntegerInputoveDamPosIndex of overriding damper position, 1: set to close; 2: set to open
Buildings.Controls.OBC.CDL.Interfaces.RealInputuDamDamper commanded position
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputuHeaOffOverride heating valve position, true: close heating valve
Buildings.Controls.OBC.CDL.Interfaces.RealInputuValHeating valve commanded position
Buildings.Controls.OBC.CDL.Interfaces.IntegerInputoveFanIndex of overriding fan status, 1: turn fan off; 2: turn fan on
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputu1FanTerminal fan status
Buildings.Controls.OBC.CDL.Interfaces.RealOutputyDamDamper commanded position, after considering override
Buildings.Controls.OBC.CDL.Interfaces.RealOutputyValHeating valve commanded position, after considering override
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutputy1FanFan status after considering override

Components

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Integers.Sources.ConstantconInt3Constant 1
Buildings.Controls.OBC.CDL.Integers.EqualintEqu3Check if forcing damper to full close
Buildings.Controls.OBC.CDL.Integers.EqualintEqu4Check if forcing damper to full open
Buildings.Controls.OBC.CDL.Integers.Sources.ConstantconInt4Constant 2
Buildings.Controls.OBC.CDL.Conversions.BooleanToRealcloDamFull closed damper position
Buildings.Controls.OBC.CDL.Conversions.BooleanToRealopeDamFull open damper position
Buildings.Controls.OBC.CDL.Reals.Addadd3Add up inputs
Buildings.Controls.OBC.CDL.Logical.Oror2Check if the damper setpoint position should be overrided
Buildings.Controls.OBC.CDL.Reals.Switchswi1Damper setpoint position after considering override
Buildings.Controls.OBC.CDL.Reals.MultiplyproValve position setpoint after considering override
Buildings.Controls.OBC.CDL.Conversions.BooleanToRealbooToReaConvert boolean true to real 0
Buildings.Controls.OBC.CDL.Integers.Sources.ConstantconInt5Constant 1
Buildings.Controls.OBC.CDL.Integers.EqualintEqu1Check if forcing fan to turn off
Buildings.Controls.OBC.CDL.Integers.EqualintEqu2Check if forcing fan to turn on
Buildings.Controls.OBC.CDL.Integers.Sources.ConstantconInt6Constant 2
Buildings.Controls.OBC.CDL.Logical.SwitchlogSwiFan status after considering override
Buildings.Controls.OBC.CDL.Logical.Sources.ConstantconTurn fan off
Buildings.Controls.OBC.CDL.Logical.SwitchlogSwi1Logical switch
Buildings.Controls.OBC.CDL.Logical.Sources.Constantcon1Turn fan on

Revisions

  • August 1, 2020, by Jianjun Hu:
    First implementation.