blockAlarms

Zone level alarms

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Information

This block outputs zone alarms. The implementation is according to the ASHRAE Guideline 36, Section 5.3.6.

Zone temperature alarm

High-temperature alarm
- If the zone temperature TZon is 2 °C (3 °F) above the cooling setpoint TCooSet for 10 minutes (timChe), generate Level 3 alarm.
- If the zone temperature TZon is 3 °C (5 °F) above the cooling setpoint TCooSet for 10 minutes (timChe), generate Level 2 alarm.
Low-temperature alarm
- If the zone temperature TZon is 2 °C (3 °F) below the heating setpoint THeaSet for 10 minutes (timChe), generate Level 3 alarm.
- If the zone temperature TZon is 3 °C (5 °F) below the heating setpoint THeaSet for 10 minutes (timChe), generate Level 2 alarm.
Suppress zone temperature alarms as follows:
- After zone setpoint is changed per Section 5.1.20 of Guideline 36, uResSet=true.
- While zone group is in warm-up or cooldown modes.

For zones with CO2 sensors:

If the CO2 concentration ppmCO2 is less than 300 ppm, or the zone is in unoccupied mode for more than 2 hours (modChe) and zone CO2 concentration exceeds 600 ppm, generate a Level 3 alarm. The alarm text shall identify the sensor and indicate that it may be out of calibration.
If the CO2 concentration exceeds setpoint (CO2Set) plus 10% for more than 10 minutes (timChe), generate a Level 2 alarm.

Parameters

Type	Name	Default	Description
Real	timChe	600	Threshold time to check temperature difference
CO2 concentration alarm
Boolean	have_CO2Sen	false	True: the zone has CO2 sensor
Real	modChe	7200	Threshold time to check unoccupied time
Real	CO2Set	894	CO2 setpoint in ppm
Advanced
Real	dTHys	0.25	Delta between the temperature hysteresis high and low limit
Real	ppmHys	25	Hysteresis to check CO2 concentration

Connectors

Type	Name	Description
Buildings.Controls.OBC.CDL.Interfaces.RealInput	TZon	Measured zone temperature
Buildings.Controls.OBC.CDL.Interfaces.RealInput	TCooSet	Zone cooling setpoint
Buildings.Controls.OBC.CDL.Interfaces.RealInput	THeaSet	Zone heating setpoint
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput	u1ResSet	True: zone setpoint temperature is being resetted
Buildings.Controls.OBC.CDL.Interfaces.IntegerInput	uOpeMod	AHU operation mode status signal
Buildings.Controls.OBC.CDL.Interfaces.RealInput	ppmCO2	Measured CO2 concentration
Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput	yTemAla	Zone temperature alarm
Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput	yCO2Ala	CO2 concentration alarm

Components

Type	Name	Description
Buildings.Controls.OBC.CDL.Reals.Subtract	lowTem	Zone temperature below the heating setpoint
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold	twoDegLow	Check if the zone temperature is 2 degC lower than the heating setpoint
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold	thrDegLow	Check if the zone temperature is 3 degC lower than the heating setpoint
Buildings.Controls.OBC.CDL.Reals.Subtract	higTem	Zone temperature above the cooling setpoint
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold	twoDegHig	Check if the zone temperature is 2 degC higher than the cooling setpoint
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold	thrDegHig	Check if the zone temperature is 3 degC higher than the cooling setpoint
Buildings.Controls.OBC.CDL.Utilities.Assert	higTemAla3	Level 3 high temperature alarm
Buildings.Controls.OBC.CDL.Logical.Not	not1	Logical not
Buildings.Controls.OBC.CDL.Logical.Not	notSupTemAla	Do not suppress temperature alarms
Buildings.Controls.OBC.CDL.Logical.And	and2	Check if alarms should be generated
Buildings.Controls.OBC.CDL.Logical.And	and1	Check if alarms should be generated
Buildings.Controls.OBC.CDL.Logical.And	and3	Check if alarms should be generated
Buildings.Controls.OBC.CDL.Logical.And	and4	Check if alarms should be generated
Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger	booToInt	Level 3 high temperature alarm
Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger	booToInt2	Level 3 low temperature alarm
Buildings.Controls.OBC.CDL.Integers.Equal	levThrHig	Check if generating level 3 high temperature alarm
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	levTwo	Level 2 alarm
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	levThr	Level 3 alarm
Buildings.Controls.OBC.CDL.Utilities.Assert	higTemAla2	Level 2 high temperature alarm
Buildings.Controls.OBC.CDL.Logical.Not	not2	Logical not
Buildings.Controls.OBC.CDL.Integers.Equal	levTwoHig	Check if generating level 2 high temperature alarm
Buildings.Controls.OBC.CDL.Utilities.Assert	lowTemAla3	Level 3 low temperature alarm
Buildings.Controls.OBC.CDL.Logical.Not	not3	Logical not
Buildings.Controls.OBC.CDL.Integers.Equal	levThrLow	Check if generating level 3 low temperature alarm
Buildings.Controls.OBC.CDL.Utilities.Assert	lowTemAla2	Level 2 low temperature alarm
Buildings.Controls.OBC.CDL.Logical.Not	not4	Logical not
Buildings.Controls.OBC.CDL.Integers.Equal	levTwoLow	Check if generating level 2 low temperature alarm
Buildings.Controls.OBC.CDL.Reals.LessThreshold	lesThr	Check if the CO2 concentration is less than threshold
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold	greThr	Check if the CO2 concentration is greater than threshold
Buildings.Controls.OBC.CDL.Logical.And	and5	Check if it has been in unoccupied mode for long time and CO2 concentration exceeds threshold
Buildings.Controls.OBC.CDL.Utilities.Assert	lowTemAla4	Level 3 CO2 alarm
Buildings.Controls.OBC.CDL.Logical.Not	not5	Logical not
Buildings.Controls.OBC.CDL.Reals.GreaterThreshold	greThr1	Check if the CO2 concentration exceeds setpoint plus 10%
Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger	booToInt4	Level 3 CO2 concentration alarm
Buildings.Controls.OBC.CDL.Logical.Not	not6	Logical not
Buildings.Controls.OBC.CDL.Logical.And	and6	Check if it has been in unoccupied mode for long time and CO2 concentration exceeds threshold
Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger	booToInt5	Level 2 CO2 concentration alarm
Buildings.Controls.OBC.CDL.Utilities.Assert	lowTemAla5	Level 2 CO2 alarm
Buildings.Controls.OBC.CDL.Integers.Add	temAla	Zone temperature alarm
Buildings.Controls.OBC.CDL.Integers.Add	co2Ala	CO2 concentration alarm
Buildings.Controls.OBC.CDL.Logical.TrueDelay	tenMinDur	Check if it has been over threshold time
Buildings.Controls.OBC.CDL.Logical.TrueDelay	tenMinDur1	Check if it has been over threshold time
Buildings.Controls.OBC.CDL.Logical.TrueDelay	tenMinDur2	Check if it has been over threshold time
Buildings.Controls.OBC.CDL.Logical.TrueDelay	tenMinDur3	Check if it has been over threshold time
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	cooDowMod	Cool down mode
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	warUpMod	Warm-up mode
Buildings.Controls.OBC.CDL.Integers.Equal	intEqu3	Check if current operation mode is setback mode
Buildings.Controls.OBC.CDL.Integers.Equal	intEqu4	Check if current operation mode is warmup mode
Buildings.Controls.OBC.CDL.Logical.Or	or2	Cooldown or warm-up mode
Buildings.Controls.OBC.CDL.Logical.Or	or1	Check if the zone temperature alarms should be suppressed
Buildings.Controls.OBC.CDL.Integers.Equal	intEqu1	Check if current operation mode is warmup mode
Buildings.Controls.OBC.CDL.Integers.Sources.Constant	unoMod	Unoccupied mode
Buildings.Controls.OBC.CDL.Logical.TrueDelay	twoHou	Check if it has been in unoccupied mode by threshold time
Buildings.Controls.OBC.CDL.Logical.Or	or3	Check if should generate level 3 alarm
Buildings.Controls.OBC.CDL.Logical.TrueDelay	tenMinDur4	Check if it has been over threshold time
Buildings.Controls.OBC.CDL.Integers.Switch	higTemAla	High temperature alarms
Buildings.Controls.OBC.CDL.Integers.Switch	lowTemAla	Low temperature alarms

Revisions

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