Chiller Plant Control

Active Chiller in Process

Property Reference

This property identifies the chiller being added or subtracted. If no chiller is being added or subtracted, this property reference will be null.

Active Operation

Multi-State

This property indicates the action actively being performed by Chiller Plant Control.
0=None
1=Unloading Selected Chillers
2=Confirming Chilled Water Flow
3=Confirming Chiller On
4=Disabling Chiller
5=Confirming Chiller Off
6=Turning Sys Chilled Wtr Pump On
7=Confirming Sys Chilled Wtr Flow
8=Chiller Start Interval

Add Delay Time

Numeric

This is the number of minutes that an add request must exist before it is confirmed. This delay time prevents unnecessary chiller cycling due to short-lived load variations. Forced adds (initiated via a button on a status display) and adds generated during a rapid powerfail recovery are not subject to this delay. Range: 1 to 30 minutes. Default: 10 minutes.

Add Delay Timer

Numeric

This property is used to count down the "Add Delay Time." An add request must exist for the duration of this timer before that request is confirmed and capacity is added.

Add Input: Ref

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine if an add request is generated.
0=Off
1=On

Add Request

Binary

This property indicates if an add request exists. It allows the add requests generated by Chiller Plant Control to be used outside of Chiller Plant Control. 0=No
1=Yes

Add Temperature

Numeric

This is the value used to initiate an add request (when soft start is not active). It is equal to the "System Chilled Water Stpt: Active" plus the "Add Temperature Deadband." When the value of the "Sys Chilled Wtr Supply Temp: Ref" is greater than this value, an add request is initiated.

Add Temperature Deadband

Numeric

This is the value added to the "System Chilled Water Stpt: Active" property to determine the "Add Temperature" value. Range: 0.0 to 20.0° F, Default: 2.5° F.

Alarm Event Class[1]

Numeric

This property indicates the alarm event class array index that determines which objects receive event messages generated by this Chiller Plant Control. Range: 0 to 20, Default: 0 - No Notification.

Alarm Event Class[2]

Numeric

This property indicates the alarm event class array index that determines which objects receive alarm and failure messages generated by this Chiller Plant Control. Range: 0 to 20, Default: 0 - No Notification.

Ambient Temp Lockout Deadband

Numeric

This is the number of degrees by which the "Ambient Temp Lockout Sensor" property’s value must rise above the "Ambient Temp Lockout Setpoint" value before the "Ambient Temp Lockout Result" transitions to "No Lockout." Range: 2 to 20° F, Default: 2° F.

Ambient Temp Lockout Function

Binary

This property is used to enable and disable Chiller Plant Control’s ambient lockout feature.
0=Disabled (default)
1=Enabled

Ambient Temp Lockout Result

Binary

This property indicates the active status of Chiller Plant Control’s ambient lockout feature.
0=No Lockout
1=Lockout Present

Ambient Temp Lockout Sensor

Property Reference

The value of the referenced property is used by Chiller Plant Control as the ambient temperature.

Ambient Temp Lockout Setpnt

Numeric

This is the temperature where ambient temperature lockout is active (if the "Ambient Temp Lockout Sensor" value is less than or equal to this value) or inactive (if the "Ambient Temp Lockout Sensor" value is greater than this value plus the "Ambient Temp Lockout Deadband" value).
Range: 20 to 70° F, Default: 50° F.

Chilled Water Temp: Leaving Ref[1-25]

Property Reference

The value of the referenced property is displayed by Chiller Plant Control as the leaving chilled water temperature for the chiller.

Chiller Available: Active[1-25]

Binary

This property indicates whether the chiller is available based on "Chiller Available: Setup" and "Chiller Available: Ref." If either property indicates unavailable, the chiller is unavailable.
0=No
1=Yes

Chiller Available: Ref[1-25]

Property Reference

The binary value of the referenced property is used by Chiller Plant Control (along with "Chiller Available: Setup") to determine if the chiller is available or not available.
0=No
1=Yes

Chiller Available: Setup [1-25]

Binary

This binary property is used by Chiller Plant Control (along with "Chiller Available: Ref") to determine if the chiller is available or not available. The value of this property may be changed from the Chiller Plant Control status display.

Chiller Chilled Water Flow: Ref[1-25]

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine whether there is chilled water flow through the chiller.
0=No
1=Yes

Chiller Chilled Water Pump: Ref[1-25]

Property Reference

The referenced property is controlled by Chiller Plant Control to start and stop the chilled water pump associated with the chiller.

Chiller Chilled Water Setpoint[1-25]

Numeric

This value, calculated by Chiller Plant Control, may be referenced as the chilled water setpoint for the chiller.

Chiller Chilled Water Stpt: Min[1-25]

Numeric

This is the minimum value to which the Chilled Water Setpoint can be set for the chiller.

Chiller Control: Ref[1-25]

Property Reference

The referenced property is controlled by Chiller Plant Control to enable or disable the chiller.

Chiller Current Limit Setpoint[1-25]

Numeric

This value, calculated by Chiller Plant Control, may be referenced as the current limit setpoint for the chiller.

Chiller Design Capacity[1-25]

Numeric

This property indicates the nominal size of the chiller (tons or the SI equivalent). Range: 0 to 5,000 tons. Default: 0.

Chiller Design Flow[1-25]

Numeric

This property indicates the design flow of the chiller (GPM or the SI equivalent). Range: 0 to 15,000 GPM. Default: 0.

Chiller Failure Input 1: Ref[1-25]

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine if the chiller has failed.
0=Normal
1=Failed

Chiller Failure Input 2: Ref[1-25]

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine if the chiller has failed.
0=Normal
1=Failed

Chiller Failure[1-25]

Multi-State

This property indicates how the chiller has failed.
0=None (no failures)
1=Failed to Control Pump On
2=Failed to Confirm Ch Wtr Flow
3=Failed to Enable Chiller
4=Failed to Confirm Chiller On
5=Failed to Disable Chiller
6=Failed to Confirm Chiller Off
7=Failed to Control Pump Off
8=Flow Lost While Chiller Enabled
9=Chiller Failure Input 1
10=Chiller Failure Input 2

Chiller Sequence Number[1-25]

Multi-State

This property indicates where in the sequence of chillers the chiller will be enabled and disabled.
0=Chiller is disabled
1 to 25=Chiller is in the normal rotation sequence; chillers with the
                 lowest sequence numbers are turned On first and Off last
101=Base chiller
102=Peak chiller
103=Swing chiller

Chiller Sequence Type[1-25]

Multi-State

This property determines how the chiller is sequenced.
0=Normal
101=Base
102=Peak
103=Swing

Chiller Status: Ref[1-25]

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to verify that the chiller has started or stopped.
0=Off
1=On

Chiller Unload at Start[1-25]

Binary

This property indicates whether the chiller is selected to unload at start. One minute before a chiller is added, all operating chillers selected to unload at start are unloaded. The unloaded chillers remain unloaded until the added chiller has been confirmed On.
0=Disable (default)
1=Enable

Chiller Unload Current Limit[1-25]

Numeric

This is the value to which the chiller’s "Chiller Current Limit Setpoint" is set when the chiller is unloaded.
Range: 40 to 120%. Default: 80%.

Chiller Unload Request[1-25]

Binary

This property indicates if the chiller is loaded or unloaded.
0=No (loaded)
1=Yes (unloaded)

Control Feedback Delay Time

Numeric

This is the amount of time Chiller Plant Control waits for confirmation that a chiller or pump has started/stopped before considering it failed. Range: 1 to 20 minutes. Default: 10 minutes.

Control Feedback Delay Timer

Numeric

This is the timer associated with the "Control Feedback Delay Time" described above. The timer is set equal to the "Control Feedback Delay Time" when a chiller or pump is controlled. It then counts down to zero.

Cooling Capacity Enabled

Numeric

This is the sum of the "Chiller Design Capacity" properties for each chiller that is enabled.

Cooling Capacity to Subtract

Numeric

This is the cooling capacity that will be subtracted if a Subtract occurs.

Design Chilled Water Delta Temp

Numeric

This is the actual system delta temperature the chillers are expected to achieve when they are fully loaded. This value is used to determine the "Subtract Delta Temp" (when soft start is not active). It is not used if the "Subtract Method" is "flow."
Range: 0 to 20° F. Default: 10° F.

Fail on Loss of Flow

Binary

If the value of this property is "Disable," a pump’s corresponding flow status referencer is only used to prove flow and generate failures when the pump is initially turned On. If the value of this property is "Enable," flow failures are also generated any time the pump is On.
0=Disabled (default)
1=Enabled

Failure Exists

Binary

This property indicates that a failure exists in the chiller plant.
0=Normal
1=Failure

Failure Flags

ByteString

This property indicates if a referencer has failed to evaluate.

Failure Output: Ref

Property Reference

The referenced property is controlled by Chiller Plant Control to show that a failure exists.
0=Off (normal)
1=On (failure)

Flow to Subtract

Numeric

This is the flow that will be subtracted if a Subtract occurs.

Next Chiller Index to Subtract

Numeric

This is the index (1 to 25) of the chiller that will be subtracted when Chiller Plant Control next subtracts capacity. This value is 0 if there are no more chillers to subtract (i.e., all chillers are Off or only one chiller is On).

Next Chiller to Add

Property Reference

This property identifies the chiller that will be added/loaded when Chiller Plant Control decides to add capacity. If there are no more chillers to be added/loaded, the property reference will be null.

Next Chiller to Subtract

Property Reference

This property identifies the chiller that will be subtracted when Chiller Plant Control decides to subtract capacity. If there are no more chillers to be subtracted, the property reference will be null.

Number of Chillers Enabled

Numeric

This is the number of chillers currently enabled.

Object Identifier

Object ID

The unique hexadecimal ID of this object. This ID is used internally to identify the object.

Object Name

Character

This is the name assigned to the object. Range: Up to 32 characters.

Object Type

Object Type

This property indicates the object’s type (analog input, binary input, TCM, PCM, etc.).

Power Failure Recovery Mode

Multi-State

This property describes whether or not the rapid powerfail recovery feature of Chiller Plant Control is enabled.
0=Normal (default)
1=Rapid

Request Pending

Multi-State

This property is used in conjunction with the "Add Delay Timer" property and the "Subtract Delay Timer" property to determine which type of request is pending.
0=None
1=Add
2=Subtract

Retries if all Chillers Fail

Numeric

This is the number of times an attempt is made to restart the system if all chillers have been marked as failed.
Range: 0 to 20. Default: 0.

Rotation Day of Week

Numeric

This property indicates the day of the week on which the automatic weekly rotations are to occur. This property is only valid when the "Rotation Type" property is set to "Day of week.
1=Sunday
2=Monday
3=Tuesday
4=Wednesday
5=Thursday
6=Friday
7=Saturday

Rotation Input: Ref

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine when to rotate the sequence numbers in the chiller plant. The rotation occurs when the value transitions from Off to On.
0=Off
1=On

Rotation Interval

Numeric

This is the number of days (without any rotations) that must pass before a rotation occurs automatically. This property is only used when the "Rotation Type" property is set to "Fixed interval." If the "Rotation Interval" days go by without the sequence numbers being rotated by any means, an automatic rotation occurs. The automatic rotation occurs at the time specified by the "Rotation Time" property.
Range: 1 to 14 days. Default: 1.

Rotation Time

Date/Time Numeric

This is the time of day at which "Day of week" and "Fixed interval" rotations occur. This property is not used if the "Rotation Type" property is set to "None."
Range: 00:00:00 to 23:59:59. Default: 00:01:00.

Rotation Type

Multi-State

This property indicates when regular rotations occur.
0=None
1=Day of week
2=Fixed Interval

Rotation: Forced

Binary

If this property’s value is disable and a rotation is initiated, Chiller Plant Control will wait for normal load changes before it brings the actual system operation into compliance with the new rotation sequence. If this property’s value is enable and a rotation is initiated, the change will occur immediately.
0=Disable (default)
1=Enable

Rotation: Next Date and Time

Date/Time Numeric

This is the date and time when the next time-based rotation is scheduled to occur.

Security Class

BitString

This property contains the security class setup information for the Chiller Plant Control object.

Soft Start Deadband

Numeric

This value is used in conjunction with "Sys Setpoint: Active" to determine when the chiller plant will go into the soft start mode. If the "Sys Chilled Wtr Supply Temp: Ref" is greater than the "Sys Chilled Wtr Stpt: Active" plus this value, the chiller plant goes into the soft start mode. This property is not used if soft start is disabled.
Range: 0 to 30° F. Default: 20° F.

Soft Start Function

Binary

This property indicates if soft start is enabled or disabled.
0=Disable (default)
1=Enable

Soft Start Minimum Cooldown Rate

Numeric

This value is used in conjunction with "Sys Chilled Wtr Return Temp: Ref" to determine if a chiller needs to be added while in the soft start mode. If the "Sys Chilled Wtr Return Temp: Ref" is not dropping faster than this value, an add request is generated.
Range: 0.0 to 10.0° F. Default: 0.5° F.

Start Interval Timer

Numeric

This is the timer associated with the "Start Interval: Normal" and "Start Interval: Soft Start" properties described below. The timer is set equal to the appropriate value when a chiller is confirmed On. It then counts down to zero.

Start Interval: Normal

Numeric

This is the number of minutes that must pass after a chiller is started before the "Add Delay Timer" or "Subtract Delay Timer" is allowed to start. This property is not used in soft start mode.
Range: 1 to 30 minutes. Default: 20 minutes.

Start Interval: Soft Start

Numeric

This is the number of minutes that must pass after a cooling stage is enabled before the add or subtract delay timers are allowed to start counting. This property is only used in soft start mode.
Range: 1 to 60 minutes. Default: 10 minutes.

Subtract Delay Time

Numeric

This is the number of minutes that a subtract request must exist before it is confirmed. This delay time prevents unnecessary chiller cycling due to short-lived load variations. Forced subtracts (initiated via a button on the status display) are not subject to this delay.
Range: 1 to 30 minutes. Default: 20 minutes.

Subtract Delay Timer

Numeric

This property is used to count down the "Subtract Delay Time." A subtract request must exist for the duration of this timer before that request is confirmed and capacity is subtracted.

Subtract Delta Temperature

Numeric

This calculated value determines whether to generate a subtract request. If "Sys Water Delta Temp" is less than this value, a subtract request is generated. This property is valid only when the "Subtract Method" is set to "Temperature" and soft start is not active.

Subtract Flow Threshold

Numeric

This calculated value determines whether to generate a subtract request. If "Sys Bypass Flow: Ref" is greater than this value, a subtract request is generated. This property is valid only when the "Subtract Method" is set to "Flow" and soft start is not active.

Subtract Input: Ref

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine if a subtract request is generated.
0=Off
1=On

Subtract Method

Multi-State

This property indicates which method is used to generate subtract requests. The chosen subtract method will not affect how "Subtract Request" is determined while in soft start.
0=Temperature (default)
1=Flow

Subtract Request

Binary

This property indicates if a subtract request exists and allows the subtract requests generated by Chiller Plant Control to be used outside of Chiller Plant Control.
0=No
1=Yes

Subtract Temperature Deadband

Numeric

This value is used to calculate the "Subtract Delta Temp." This property is only used when the "Subtract Method" is set to "Temperature."
Range: 0.0 to 5.0° F. Default: 0.5° F.

Subtract: Excess Flow Percentage

Numeric

The excess flow in the bypass pipe must exceed, by this percentage, the design flow that is next to be subtracted.
Range: 0 to 100%. Default: 20%.

Sys Bypass Flow: Ref

Property Reference

The value of the referenced property is used by Chiller Plant Control as the flow (excess flow direction) through the bypass pipe in a decoupled system. This property is only used when the "Subtract Method" is set to "Flow."

Sys Chilled Water Delta Temp

Numeric

This is the temperature change across the building load. It is used to determine if a chiller should be subtracted. This property is only used if soft start is not active and the "Subtract Method" is set to "Temperature."

Sys Chilled Water Flow: Ref

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to determine if system flow exists.
0=No
1=Yes

Sys Chilled Water Pump: Ref

Property Reference

The value of the referenced property is controlled by Chiller Plant Control to start/stop the system pump.
0=Off
1=On

Sys Chilled Water Stpt: Active

Numeric

This is the setpoint currently being used by Chiller Plant Control.

Sys Chilled Water Stpt: Ref

Property Reference

The value of the referenced property is used by Chiller Plant Control as the system chilled water supply temperature setpoint.
Range: 1 to 65° F. Default: 45.0° F.

Sys Chilled Wtr Return Temp: Ref

Property Reference

The value of the referenced property is used by Chiller Plant Control as the temperature of the chilled water being returned to the chillers from the building load.

Sys Chilled Wtr Supply Temp: Ref

Property Reference

The value of the referenced property is used by Chiller Plant Control as the temperature of the chilled water being supplied by the chiller plant to the building load.

Sys Return Water Cooling Rate

Numeric

This value is the one-minute-old return water temperature minus the current temperature. It is positive if the return water temperature is falling and negative if it is rising.

System Enable: Ref

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to enable and disable the chiller plant.
0=Off
1=On

System Failure

Multi-State

This property indicates how a system flow failure has occurred.
0=None (no failures)
1=Failed to Control System Pump On
2=Failed to Confirm System Flow
3=Failed to Control Systm Pump Off
4=System Flow Lost

System Failure Reset: Ref

Property Reference

The binary value of the referenced property is used by Chiller Plant Control to reset system and chiller failures. The reset occurs when the value transitions from Off to On.
0=Off
1=On

System Flow Type

Multi-State

This is the type of system chilled water flow. Constant flow indicates there is flow through all chillers at all times. Variable flow indicates there is flow only through the operating chillers.
0=Variable (default)
1=Constant

System Mode

Multi-State

This property indicates the active mode of the chiller plant.
0=Off
1=Ambient Lockout
2=Shutdown in Progress
3=Soft Start
4=Normal
5=Rapid Powerfail Recovery

Total Cooling Capacity

Numeric

This is the sum of the "Chiller Design Capacity" property values from each chiller in the plant.

Update Tag

Numeric

This property indicates the last edit change of this object. This is the upload/download tag property. Its purpose is to keep the PC Workstation and BCU copies of the object instance in synchronization.