Attributes (Pump Selector) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 16.0

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
16.0
Revision date
2023-10-02
Language
English

The following table describes the attributes used by the Pump Selector modules:

Table 1. Pump Selector Attributes

Name

Type 1

Description

Default Value

Available Capacity

V

Provides the sum of the enabled pump derated capacities.

0

Display units come from Capacity Units.

Control Mode

 

Determines how the pumps are controlled:

  • Constant Speed: The Pump Selector uses the Requested Flow input to decide how many, and which pumps to command.
  • Variable Speed: This configuration assumes that there is another block in the application that controls the flow and provides the pumps speed to this module. The pump speed is used to stage up and to calculate the flow for staging down.

Constant Speed

Set Name: Pump Control Mode

Current Capacity

G, V

Provides the sum of the derated capacities of the devices currently on (that is, Device nn Status = On).

0

Display units come from Capacity Units.

Current Efficiency

V

Indicates the capacity weighted efficiency of the pumps currently commanded to On.

2.0

Display Units: %

Current Percent Load

V

Indicates the percent loading of the pumps currently commanded to On adjusted by the Derate Percent. For constant speed pumps, this value represents the percent of the flow being used to satisfy the current load requirements. For variable speed pumps, this value represents the percent of flow versus the total available flow.

0

Display Units: %

Derate Now

 

Derates the rated flow of the currently operating devices and may force an upstage. This input may be triggered, for example, by the Saturation Status of the PID that controls the Bypass Valve.

This input applies to only constant speed pumping systems, as possible pump malfunction may result in not meeting the flow requirements.

The module calculates that a Derating Percent such as the Current Percent Capacity becomes 101%. For example, if a rising edge of the Derate Now occurs when the Current Percent Capacity is 80%, the On devices are assigned a Derating Percent of 20.8% (101-80)/101*100, and are effectively rated at 79.2% of their actual rating. This value forces an immediate upstage. The Derating Percent is set to zero for all devices at the rising edge of the Derate Reset input. The individual Derating Value nn (where nn is 01-08) are properties of the module. As this condition is usually indicative of a hardware issue, the Derate Now input (or its source) should be used to set an alarm in the BAS.

False

Derate Reset

 

Resets the derating value to zero. The derate reset action is triggered at the edge of the module. See Derate Now.

False

Derating Value nn

V

Indicates the array of individual device derate values (where nn is 01-08).

0

Display Units: %

Device nn Capacity

 

Indicates the flow capacities of each device in selectable units (where nn is 01-08).

0

Display units come from Capacity Units.

Device nn Cmd

V

Provides the command requests to each pump (where nn is 01-08).

False

Device nn Enable

 

Indicates the Disable/Enable state of the devices (where nn is 01-08).

True

Device nn Peak Efficiency

 

Indicates the peak efficiency for the pumps as percentages (where nn is 01-08). This value is limited to integers between 50% and 100%.

Combinations with devices that have higher peak efficiencies are preferentially selected during operation without regard for improving run time or start count imbalances.

Only devices with the same Peak Efficiency have the ability to be balanced for run time and/or start counts. For example, if two devices have peak efficiencies X, and two other devices have peak efficiencies Y, the start count and runtime balancing happens among the devices with peak efficiencies X and among the devices with peak efficiencies Y, but not among all devices. This selection happens because the run time and start count adjustments are small decimal values that do not add up to one unit and the Peak Efficiencies are whole numbers. See Combination Efficiency.

85

Display Units: %

Range: 50-100

Device nn Runtime

 

Indicates the runtimes of the devices (where nn is 01-08).

0

Display Units: Hours

Device nn Start Count

 

Indicates the number of starts performed by each device (where nn is 01-08).

0

Device nn Status

 

Indicates the current Off/On state of the devices as reported by the hardware itself (where nn is 01-08).

Off

Set Name: Off/On

Flow Units

C

Indicates the units used for the flow depending on the Units of the application.

gpm

Set Name: Unit

Hysteresis

 

Indicates the value of an additional efficiency penalty to be applied before a change is made. Larger values increase the stability of the combination currently operating while forcing a greater drop in efficiency before a switch is made. The adjusted efficiency of the new combination includes this Hysteresis.

0.00

Display Units: %

Range: 0.00-10.00

Interstage Off Delay

 

Delay after an Off command before starting to downstage again.

15

Display Units: Min

Range: 0.1-120

Interstage On Delay

 

Delay after an On command before starting to upstage again.

15

Display Units: Min

Range: 0.1-120

CHWP LOWER PCT LOAD, CWP LOWER PCT LOAD, PCHWP LOWER PCT LOAD, SCHWP LOWER PCT LOAD (Lower Optimal Pct Load)

 

Indicates the nominal value that applies to all pumps collectively. This value is the left hand endpoint of the pump efficiency plateau. When this value decreases, the application stages down at lower percent loads. For example, a plant runs pumps with a combined capacity of 400 gpm. When the Lower Percent Load is 70%, the application considers staging down when the current required flow reduces to less than 280 gpm. If this value is reduced to 55, the application does not consider staging down until the required flow decreases to less than 220 gpm.

78

Display Units: %

CHWP UPPER PCT LOAD, CWP LOWER PCT LOAD, PCHWP LOWER PCT LOAD, SCHWP LOWER PCT LOAD (Upper Optimal Percent Load)

 

Indicates the nominal value that applies to all pumps collectively. It is the right hand endpoint of the pump efficiency plateau.

98

Display Units: %

Maximum Flow

 

For Variable Speed Mode, this input provides a maximum limit on the pumping capacity (flow) that can be turned On to prevent more capacity than required by the enabled chillers. Maximum Flow takes precedence over Minimum Flow; therefore, when this input is zero, all pumps shut off.

1e30

Display units come from Flow Units.

CHWP-MINOFFTIME, CWP-MINOFFTIME, PCHWP-MINOFFTIME, SCHWP-MINOFFTIME (Min Off Time)

 

Indicates the minimum amount of off time applied to all pumps.

1

Display Units: Min

Range: 0-60

CHWP-MINONTIME, CWP-MINONTIME, PCHWP-MINONTIME, SCHWP-MINONTIME (Min On Time)

 

Indicates the minimum amount of on time applied to all pumps.

1

Display Units: Min

Range: 0-60

CHWP BASE LOAD, CWP BASE LOAD, PCHWP BASE LOAD, SCHWP BASE LOAD (Minimum Flow)

 

Indicates the minimum capacity (flow) that the system needs to maintain. Together with the Process Variable, this input defines the minimum number of pumps to command. It is assumed that other application block, presumably the Chiller Selector module, sets the two inputs according to the chillers flow requirements, setting both of them to zero only when no flow is necessary (for example, when pump down is finished).

0

Display units come from Flow Units.

Predicted Adjusted Efficiency

SC, V

Indicates the Predicted Efficiency of the Required Devices (steady state device commands) adjusted for run time imbalances, start count imbalances, start/stop differences, user-defined efficiency hysteresis, and start/stop efficiency penalty.

0

Display Units: %

Predicted Efficiency

SC, V

Indicates the expected capacity weighted efficiency based on the Required Devices (steady state device commands).

0

Display Units: %

Predicted Percent Load

SC, V

Indicates the expected percent load based on the Required Devices (steady state device commands).

0

Display Units: %

Process Variable

 

Provides a value depending on the Control Mode property. When Control Mode is Constant Speed, the Process Variable is the Requested Flow. When Control Mode is Variable Speed, the Process Variable is the current commanded speed to all pumps. This value is calculated elsewhere in the application by a PID that controls the water pressure drop across the load.

0

When Mode is Constant Speed, the Display units come from Process Variable Units.

When Mode is Variable Speed, the display units is %.

Process Variable Units

 

Indicates the units used for the Process Variable depending on the Units of the application and the Mode of Operation.

kW

Set Name: Unit

Required Devices

SC, V

Provides an integer output representing the packed bits of the desired steady state set of pumps commanded On.For example, a value of 4 means 1-0-0, which indicates pump 3 is On and pumps 2 and 1 are Off.

0

Required Interim Devices

SC, V

Provides an integer output representing the packed bits of the intermediate devices requested to turn on while the pump selector moves toward the desired steady state.

0

Rotate Now

 

Causes an immediate re-evaluation of the required devices to provide the required capacity to meet the current required flow based on the current Device Runtime or Start Counts or both.

False

Rotation Mode

 

Determines how rotation is processed:

  • 0: None. The module does not attempt to equalize either runtimes or start counts of the individual devices.
  • 1: Run Time. The module attempts to equalize the runtimes of the individual devices.
  • 2: Start Counts. The module attempts to equalize the start counts of the individual devices.
  • 3: Both. The module attempts to equalize both start counts and run times of the individual devices.

None

Set Name: Rotation Mode

Sequence Row Control

  Enables Sequence Row parameter to enable devices.

False

Sequence Row

 

Indicates the sequence table row number that the module attempts to move toward while following device timers and statuses. This input is available when the Sequence Row Control input is True. If the input value is out of range or if a sequence table is not present, Sequence Row input is ignored.

0

Sequence Row Transition Delay

 
When Sequence Row becomes False, this indicates the amount of time the selector does not make any staging decisions.
Note: This time is ignored when System Enabled becomes False.

Default: 0.2 minutes

Minimum: 0.1 minutes

Stabilize Time

 

Indicates the amount of time to wait after a pump is commanded off or on before evaluating if the current combination of pumps is meeting the current demand, or if another pump should be turned on or off. This should reflect the amount of time it takes for a pump to ramp up its commanded speed, and the amount of time it takes for the system to recognize a change to the process variable.

0

Display Units: Min

Staging Margin

 

When considering a downstage combination, the percent load actually increases by this value when performing the efficiency calculation. This method provides a safety margin as the percent load is a theoretical value, and the actual percent load of the new combination could be higher than calculated.

When considering an upstage combination, the percent load actually reduces by this value when performing the efficiency calculation. This method provides a safety margin as the actual percent load of the new combination could be lower than calculated.

Since the Upper Optimal Pct Load is typically closer to 100% than the Lower Optimal Pct Load is to 0%, the slope of the right hand side curve is much steeper than the left hand side slope; therefore, when the load is increasing, the system efficiency of the current combination drops faster compared with the slower increase of efficiency of the new combination, allowing the algorithm to switch to a new stage.

2.0

Display Units: %

Range: 0.0-10.0

System Enable

 

Disables/enables the pump selector. When System Enabled is False, the Pump Selector downstages to zero capacity.

False

CHWP UPPER PCT LOAD, CWP UPPER PCT LOAD, PCHWP UPPER PCT LOAD, SCHWP UPPER PCT LOAD (Upper Optimal Pct Load)

 

Indicates the nominal value that applies to all pumps collectively. This value is the right hand endpoint of the pump efficiency plateau. When this value increases, the application stages up at higher percent loads. For example, a plant runs pumps with a combined capacity of 400 gpm. When the Upper Percent Load is 80%, the application considers staging up when the current required flow exceeds 320 gpm. If this value is changed to 95, the application does not consider staging up until the required flow exceeds 380 gpm.

98

Display Units: %

Maximum Value: 99.9

1 C - Configuration Mode Only, G - Default Element (Generated State, if applicable), SC - Simulation and Commissioning Modes Only, V - Calculated Value (Outputs)