blockFailsafeCondition

Evaluate failsafe stage up condition

Information

For heating applications with primary-secondary distribution: The failsafe stage up condition evaluates to true if either of the following is true.

Secondary HW supply temperature < primary HW supply temperature - dT for a period of dtSec and secondary HW supply temperature < setpoint – dT for dtSec.
Primary HW supply temperature < setpoint - dT for dtPri.

For heating applications with primary-only distribution: The failsafe stage up condition evaluates to true if the following is true.

For cooling applications with primary-secondary distribution: The failsafe stage up condition evaluates to true if either of the following is true.

Secondary CHW supply temperature > primary CHW supply temperature + dT for a period of dtSec and secondary CHW supply temperature < setpoint + dT for dtSec.
Primary CHW supply temperature > setpoint + dT for dtPri.

For cooling applications with primary-only distribution: The failsafe stage up condition evaluates to true if the following is true.

Type	Name	Default	Description
Buildings.Templates.Plants.Controls.Types.Application	typ		Type of application
Boolean	have_pumSec		Set to true for primary-secondary distribution, false for primary-only
Real	dT		Delta-T triggering stage up command (>0)
Real	dtPri	900	Runtime with high primary-setpoint Delta-T before staging up
Real	dtSec	600	Runtime with high secondary-primary and secondary-setpoint Delta-T before staging up

Type	Name	Description
Buildings.Controls.OBC.CDL.Interfaces.RealInput	TSecSup	Secondary supply temperature
Buildings.Controls.OBC.CDL.Interfaces.RealInput	TPriSup	Primary supply temperature
Buildings.Controls.OBC.CDL.Interfaces.RealInput	TSupSet	Supply temperature setpoint
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput	reset	Reset timers to zero at completion of stage change
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput	y1	Failsafe stage up condition met

Type	Name	Description
Buildings.Controls.OBC.CDL.Reals.Subtract	dTSecPri	Secondary-primary ∆T
Buildings.Controls.OBC.CDL.Reals.Subtract	dTPriSet	Primary-setpoint ∆T
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter	polHeaCoo	Polarity depending on heating or cooling application
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter	polHeaCoo1	Polarity depending on heating or cooling application
Buildings.Controls.OBC.CDL.Reals.LessThreshold	lesPriSet	True if Delta-T less than threshold
Buildings.Controls.OBC.CDL.Reals.LessThreshold	lesSecPri	True if Delta-T less than threshold
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Generic.TimerWithReset	timPriSet	Timer
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Generic.TimerWithReset	timSecPri	Timer
Buildings.Controls.OBC.CDL.Logical.Or	any	Any criterion met
Utilities.PlaceholderLogical	ph	Placeholder signal
Buildings.Controls.OBC.CDL.Reals.Subtract	dTSecSet	Secondary-setpoint ∆T
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter	polHeaCoo2	Polarity depending on heating or cooling application
Buildings.Controls.OBC.CDL.Reals.LessThreshold	lesSecSet	True if Delta-T less than threshold
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Generic.TimerWithReset	timSecSet	Timer
Buildings.Controls.OBC.CDL.Logical.And	allSec	All criteria on secondary temperature met