blockOverrides

Software switches to override setpoints

Information

This block considers the overrides to the setpoints for terminal unit with reheat. The implementation is according to the Section 5.6.7 of ASHRAE Guideline 36, May 2020.

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

when oveDamPos equals to 1, force the damper to full closed by setting yDam to 0,
when oveDamPos equals to 2, force the damper to full open by setting yDam to 1.
when uHeaOff equals to true, force the heating valve to full closed by setting yVal to 0.

Connectors

Type	Name	Description
Buildings.Controls.OBC.CDL.Interfaces.IntegerInput	oveDamPos	Index of overriding damper position, 1: set to close; 2: set to open
Buildings.Controls.OBC.CDL.Interfaces.RealInput	uDam	Damper commanded position
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput	uHeaOff	Override heating valve position, true: close heating valve
Buildings.Controls.OBC.CDL.Interfaces.RealInput	uVal	Heating valve commanded position
Buildings.Controls.OBC.CDL.Interfaces.RealOutput	yDam	Damper commanded position, after considering override
Buildings.Controls.OBC.CDL.Interfaces.RealOutput	yVal	Heating valve commanded position, after considering override

Components

Type	Name	Description
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	conInt3	Constant 1
Buildings.Controls.OBC.CDL.Integers.Equal	intEqu3	Check if forcing damper to full close
Buildings.Controls.OBC.CDL.Integers.Equal	intEqu4	Check if forcing damper to full open
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	conInt4	Constant 2
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal	cloDam	Full closed damper position
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal	opeDam	Full open damper position
Buildings.Controls.OBC.CDL.Reals.Add	add3	Add up inputs
Buildings.Controls.OBC.CDL.Logical.Or	or2	Check if the damper setpoint position should be overrided
Buildings.Controls.OBC.CDL.Reals.Switch	swi1	Damper setpoint position after considering override
Buildings.Controls.OBC.CDL.Reals.Multiply	pro	Valve position setpoint after considering override
Buildings.Controls.OBC.CDL.Conversions.BooleanToReal	booToRea	Convert boolean true to real 0

Revisions

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