Installation Electrical
72 RTHD-SVX02H-EN
Table 20. Chiller Events/Status Descriptions
Event/State Description
Alarm - Latching This output is true whenever there is any active diagnostic that requires a manual reset to clear, that effects
the Chiller, the Circuit, or any of the Compressors on a circuit. This classication does not include informa-
tional diagnostics.
Alarm - Auto Reset This output is true whenever there is any active diagnostic that could automatically clear, that effects the
Chiller, the Circuit, or any of the Compressors on a circuit. This classication does not include informational
diagnostics. If all of the auto resetting diagnostics were to clear, this output would return to a false condition.
Alarm This output is true whenever there is any diagnostic effecting any component, whether latching or automati-
cally clearing. This classication does not include informational diagnostics.
Warning This output is true whenever there is any informational diagnostic effecting any component, whether latching
or automatically clearing.
Chiller Limit Mode This output is true whenever the chiller has been running in one of the Unloading types of limit modes
(Condenser, Evaporator, Current Limit or Phase Imbalance Limit) continuously for the last 20 minutes. A
given limit or overlapping of different limits must be in effect continuously for 20 minutes prior to the output
becoming true. It will become false, if no Unload limits are present for 1 minute. The lter prevents short
duration or transient repetitive limits from indicating. The chiller is considered to be in a limit mode for the
purposes of front panel display and annunciation, only if it is fully inhibiting loading by virtue of being in
either the “hold” or “forced unload” regions of the limit control, excluding the “limited loading region”. (In
previous designs, the “limit load” region of the limit control was included in the criteria for the limit mode call
out on the front panel and annunciation outputs)
Compressor Running The output is true whenever any compressors are started or running on the chiller and false when no com-
pressors are either starting or running on the chiller.
This status may or may not reect the true status of the compressor in Service Pumpdown if such a mode
exists for a particular chiller.
Chiller Head Pressure
Relief Request Relay
This relay output is energized anytime the chiller is running in one of the following modes; Ice Making Mode
or Condenser Pressure Limit Control Mode continuously for the duration specied by the Chiller Head Relief
Relay Filter Time. The Chiller Head Relief Relay Filter Time is a service setpoint. The relay output is de-en-
ergized anytime the chiller exits all above modes continuously for the duration specied by the same Chiller
Head Relief Relay Filter Time.
The UC800 Service Tool (Tracer TU) is used to install and
assign any of the above listed events or status to each of
the four relays provided with this option.
The default assignments for the four available relays are
listed below.
Table 21. Programable Relays
LLID Name LLID Software
Relay Designation
Output Name Default
Operating Status Pro-
grammable Relays
Relay 0 Status Relay 4, J2-1,2,3 Head Pressure Relief Request
Relay 1 Status Relay 3, J2-4,5,6 Chiller Limit Mode Relay
Relay 2 Status Relay 2, J2-7,8,9 Chiller Alarm Relay (latching or nonlatching)
Relay 3 Status Relay 1, J2-10,11,12 Compressor Running Relay
Emergency Stop
The UC800 provides auxiliary control for a customer
specified/installed latching trip out. When this custom-
er-furnished remote contact is provided, the chiller will
run normally when the contact is closed. When the con-
tact opens, the unit will trip off on a manually resettable
diagnostic. This condition requires manual reset at the
chiller switch on the front of the control panel.
External Auto/Stop
If the unit requires the external Auto/Stop function, the
installer must provide leads from the remote contacts to
the proper terminals of the LLID on the control panel.
The chiller will run normally when the contacts are
closed. When the contact opens, the compressor(s), if
operating, will go to the RUN:UNLOAD operating mode
and cycle off. Unit operation will be inhibited. Re-clo-
sure of the contacts will permit the unit to automatically
return to normal operation.
Note: A “panic” stop (similar to “emergency” stop) can
be manually commanded by pressing the STOP
button twice in a row, the chiller will immediately
shut down, but without creating a latching diag-
nostic.
Programmable Relays (Alarm and Status) -
Optional
UC800 provides a flexible alarm or chiller status indica-
tion to a remote location through a hard wired interface
to a dry contact closure. Four relays are available for this
function, and they are provided (generally with a Quad
Relay Output LLID) as part of the Alarm Relay Output
Option.
The events/states that can be assigned to the program-
mable relays are listed in the following table.
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