Installation and Maintenance Manual

Controls
46 RTAE-SVX001B-EN
Alarms
You can use the display to view alarms and to reset them.
Alarms are communicated to the display immediately
upon detection.
Viewing the Alarms Screen
Touch the Alarms button in the main menu area (Figure 30,
p. 44) to view the Alarms screen. A table of active alarms
appears that is organized chronologically with the most
recent at the top of the list, as shown in Figure 32.This
example shows the default view, which appears each time
you return to the screen.
Note: A page number appears in the lower right corner of
the screen. If a screen contains more than one
page, up/down arrows also appear for viewing the
other pages
The Alarms screen is accessible by depressing the Alarms
enunciator. A verbal description will be provided.
A scrollable list of the last active Alarms is presented.
Performing a “Reset Alarms” will reset all active Alarms
Condenser Pressure Limit
The circuit is experiencing condenser pressures at or near the condenser limit setting. Compressors on the
circuit will be unloaded to prevent exceeding the limits.*
Low Evaporator Refrigerant
Temperature Inhibit
The circuit is experiencing saturated evaporator temperatures at or near the Low Refrigerant Temperature
Cutout setting. Compressors on the circuit will be unloaded to prevent tripping. *
Capacity Limited by Low Liquid Level
The circuit is experiencing low refrigerant liquid levels and the EXV is at or near full open. The compressors
on the circuit will be unloaded to prevent tripping.*
Current Limit
The compressor is running and its capacity is being limited by high currents. The current limit setting is
100% RLA (to avoid overcurrent trips) or lower as set by the compressor’s “share” of the active current
limit (demand limit) setting for the entire chiller.*
Phase Unbalance Limit The compressor is running and its capacity is being limited by excessive phase current unbalance.*
Low Discharge Superheat Limit
This is limit control that acts to prevent chiller shutdown when the discharge superheat approaches the
limit setpoint by reducing the liquid level and unloading the slide valve.
Oil Loss Avoidance
This is limit control that acts to prevent chiller shutdown when the estimated refrigerant flow approaches
the calculated minimum flow by increasing the slide valve capacity and/or VFD frequency
Note: Other normal running modes (see above) may also appear under this top level mode
Shutting Down
The chiller is still running but shutdown is imminent. The chiller is going through a compressor
run-unload. sequence. Shutdown is necessary due to one (or more) of the following sub-modes:
Local Stop Chiller is in the process of being stopped by TD7 Stop button command
immediate Stop Chiller is in the process of being stopped by TD7 Panic Stop command
Diagnostic Shutdown – Manual Reset
Chiller is in the process of being stopped by a Latching Diagnostic shutdown – Manual Reset is required
to clear
Diagnostic Shutdown – Auto Reset
Chiller is in the process of being stopped by a Diagnostic shutdown – Automatic clearing of the diagnostic
is possible if condition clears.
Compressor Unloading (min:sec)
The compressor is in its “run – unload” state in which it is being continuously unloaded for 40 sec prior
to shutdown.
Starting is Inhibited by External
Source
Chiller is in the process of being stopped by the External Stop hardwired input
Start Inhibited by BAS
The Chiller is in the process of shutdown due to a command from the Building Automation System (e.g.
Tracer)
Evaporator Water Pump Off Delay
min:sec
Service Override The Chiller is in a Service Override mode
Service Pumpdown
The chiller, circuit, and compressor is running via a manual command to perform a Service Pumpdown.
Both evap and condenser water pumps are commanded to be running. The EXV is being held wide open,
but the manual liquid line service valve should be closed.
Table 24. Operating modes (continued)
Chiller Modes Description
Figure 32. Alarm screen