Trane CITY RTSF Series Manual page 25

The Tracer UC800 Service Tool (TU) is used to install and assign any of the above listed events or status to each of the
4 relays. The default assignments for the 4 available relays are listed below.
LLID Name
Operating Status
Programmable Relays
If the evaporator/condenser pump request relays are not used to manage the evaporator/condenser water pumps
then the evaporator/condenser freeze avoidance request relays must be connected to the water pump management
system to switch the water pumps ON when the Tracer UC800 identifi es a risk of freeze up.
Latching input
The Tracer UC800 provides auxiliary control for a customer specifi ed/installed latching trip out. When this customer-
furnished remote contact is provided, the chiller will run normally when the contact is closed. When the contact
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-closure 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 diagnostic.
Soft Loading
Soft loading will prevent the chiller from going to full capacity during the pull-down period. The Tracer UC800 control
system has two soft loading algorithms running all of the time. They are capacity control soft loading and current
limit soft loading. These algorithms introduce the use of a Filtered Chilled Water Setpoint and a Filtered Current Limit
Setpoint. After the compressor has been started, the starting point of the fi ltered chilled water setpoint is initialized
to the value of the Evap Leaving Water Temperature. The fi ltered current limit setpoint is initialized to the value of the
Current Limit Softload Starting Percent. These fi ltered setpoints allow for a stable pull-down that is user adjustable in
duration. They also eliminate sudden transients due to setpoint changes during normal chiller operation.
3 settings are used to describe the behavior of soft loading. The setup for soft loading can be done using TU.
• Capacity Control Softload Time: This setting controls the time constant of the Filtered Chilled Water Setpoint.
It is settable between 0 and 120 min.
• Current Limit Control Softload Time: This Setting controls the time constant of the Filtered Current Limit Setpoint.
It is settable between 0 and 120 minutes.
• Current Limit Softload Starting %: This setting controls the starting point of the Filtered Current Limit Setpoint.
It is adjustable from 20 to 100% RLA.
RLC-SVX023B-GB
LLID Software
Relay Designation
Relay 0
Relay 1
Relay 2
Relay 3
Installation - Electrical
Output Name
Status Relay 1, J2-1,2,3
Status Relay 2, J2-4,5,6
Status Relay 3, J2-7,8,9
Status Relay 4, J2-10,11,12
Default
Evaporator Freeze Avoidance
Request
Condenser Freeze Avoidance
Request
Compressor Running
Latching Alarm
25