Sequence Of Operations; Purge Operating Modes; Adaptive Mode; Adaptive Mode Process-Chiller - Trane PRGD series Installation, Operation And Maintenance Manual

Sequence of Operations

A Tracer® UC800 controller that is configured to
control a purge system uses the operational sequences
described in this section.

Purge Operating Modes

Purge operating mode options are as follows:
• S S t t o o p p . . The purge condensing unit does not run in
this mode.
• O O n n . . The purge condensing unit runs continuously
in this mode, regardless of the chiller's operational
status.
• A A u u t t o o . . The purge condensing unit runs in this mode
if the main compressor of the chiller is operating.
• A A d d a a p p t t i i v v e e . . The purge condensing unit operation
depends on past purge activity.

Adaptive Mode

The objectives of operating the unit in the Adaptive
mode are to:
• Enable purge system operation.
• Enable the refrigeration circuit to effectively
accumulate non-condensables whether or not the
chiller is running.
• Provide information to an operator regarding
whether leakage is on the high-pressure or low-
pressure side of the chiller.
• Decrease energy usage by running the purge
refrigeration circuit only when needed to remove
non-condensables, rather than running it
continuously.
PRGD-SVX01F-EN
The Adaptive mode requires historical operating data
so that the controller can make optimal decisions
regarding how to run the purge refrigeration circuit in
the future. On initial start-up of a chiller that is in
Adaptive mode, the purge refrigeration circuit runs
continuously for 168 hours (7 days). The chiller
compressor may or may not be running during this
period.
Following the initial data collection period, the
Adaptive mode customizes the purge refrigeration
circuit operation during two distinct chiller operating
conditions:
• Chiller compressor On
• Chiller compressor Off
Adaptive Mode Process—Chiller

Compressor On

The following figure illustrates the process described in
this subsection.
When the chiller compressor starts, the purge
refrigeration circuit starts. The purge refrigeration
circuit continues to run until 60 consecutive minutes of
running occur without any pump-out of non-
condensables. The Pumpout Time is the greater of the
following two values that the controller has been
tracking:
• The pump-out time with the chiller On, over the last
24 hours
• The average daily pump-out time with the chiller
On, over the last 7 days
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