Trane Thermafit TACW - Compressor Staging Valves and Optional Functions

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ARTC-SVX007A-EN
Table 14. Fan state map (continued)
Fan State Definition
4 Start
5 Cooling
Compressor Staging Valve Control
All compressors Staging Valves controls can be accessed
from compressors screen Main Menu →Comp button →
Staging button. Controls are available for Tech level HMI
users and above.
Each Staging Valve controls consist of 2 components:
1. Mode selector
2. Valve status light
Figure 34. Staging valves control screen
As per control options, each Staging Valve can be in one of
the modes:
1. Off – staging valve is always off regardless of other
conditions.
2. On – staging valve is forced on. Used mostly for
troubleshooting or maintenance purposes.
3. Auto – staging valve is controlled automatically as
compressor cycles through its states.
Optional Functionalities
The following table lists the Optional Functionalities of this
control system:
Table 15. Chiller control system Optional Functionalities list
Function Brief Access Level
Free Cooling with
ArcticBoost
Module can operate with extremely low head pressure to provide near free cooling.
Tech
Pump and Plant controls Monitor and Control evaporator and condenser pumps functions
Tech
Data Logging Displays chillers / compressors key data logged to CSV files
Admin
Primary/Secondary Monitor and Control multiple chillers Primary/Secondary functions
Tech
Economizer
Monitor and Control compressors economizers functions
Tech
Hot Gas Bypass Valve Monitor and Control compressors Hot Gas Bypass functions
Tech
Free Cooling
ArcticBoost (Low Lift Refrigerant Pump)
ArcticBoost provides free cooling without additional coils or
external coolers. The ArcticBoost function allows
compressors to operate at very low pressure ratios by
providing a refrigerant pump to aid in motor cooling.
As condensing temperature reduce and become close to
chiller side temperatures, pressure ratio (PR) reduces.
When the PR drops below the Enable threshold (User-
Settable – default is 1.3), the ArcticBoost function is
Enabled and stays enabled until the PR rises above the
Disable threshold (Enable Threshold plus 0.3).
While ArcticBoost function is Enabled, the control monitors
both the Inverter and Cavity temperatures of the
compressors. If either temp rises above the cooling
required threshold (Default based on compressor solenoid
valves but user-settable is 113.0°F), pump is enabled.
When both temperatures drop below cooling no longer
required threshold (Default, Settable – 108.0°F), pump is
turned off and remains off for the Anti-Cycle period
(Default, Settable – 30 seconds).
Operating Procedures