Hgbp Mode, Igv Target - Trane CVHE Troubleshooting Manual

UCP2 will accept a contact closure input to initiate Ice building. When in the ice making mode,
the compressor will be fully loaded and will continue to operate until the ice contacts open or the
return water temperature reaches an Adjustable Termination Setpoint. If terminated on return
setpoint, UCP2 will not allow the chiller to restart until the ice making contact is opened.
UCP2 will provide an output contact closure that can be used as a signal to the system that ice
making is in operation. This relay will be closed when ice making is in progress and open when
ice making has been terminated by either UCP2 or the remote interlock. It is used to signal the
system changes required to convert to and from ice making.
Ice mode operation will be indicated by an "Ice Building" operation mode that can be displayed at
the unit or communicated over the communications link.
The UCM shall provide a Service level Enable/Disable menu entry for the Ice Building feature
when the Ice Building Option is installed.
The UCM shall accept either an isolated contact closure (call it External Ice) or a Remote
Communicated input (Tracer) to initiate an Ice building mode where the unit runs fully loaded at
all times. Ice building shall be terminated either by opening the contact or based on entering
evaporator water temperature. The UCM shall not permit the Ice Building mode to be entered
again until the unit is switched to the Non-Ice Building mode and back into the Ice Building mode.
It is not acceptable to reset the CWS low to achieve a fully loaded compressor; the UCM shall
force the compressor to full load.
When entering ICE-BUILDING the compressor is loaded at its maximum rate and when leaving
ICE-BUILDING the compressor is unloaded at its maximum rate. For CTV only: while loading
and unloading the compressor all surge detection is ignored.
Implementation Note: Surge detection is not explicitly prevented while loading and
unloading the chiller. While the above requirement is valid it is not expected that a
surge would be detectable during the relatively short load and unload intervals.
In Ice building, softloading and current limit setpoints less than the maximum are all ignored. For
example, if the Front Panel Current Limit setpoint is set to 80%, in Ice Building the Active Current
Limit setpoint is automatically reset to its maximum value.
In the Ice Building mode if the unit gets down to the freezestat setting (water or refrigerant) the
unit will shutdown on a diagnostic, just like in normal operation.
Condenser, current and evaporator limits are active during Ice Building.
If any other limits are placed on IGV or Slide Valve stroke during Normal Cooling, the UCM will
ignore these limits during ICE-BUILDING; that is, the IGVs or Slide Valve will be fully loaded/
stroked/extended during ICE BUILDING.
ICE-BUILDING and ICE-BUILDING COMPLETE are modes displayed by the UCM at the front
panel and communicated to the Tracer.
CVHE-SB-32A
Ice Machine Control
102