Trane CenTraVac Duplex CDHF Operation & Maintenance Manual page 21

CDHF-SVU01C-EN
General
Information
Compressor Load Balancing
Duplex chillers with CH530 control
will balance the compressor load by
giving each compressor the same
load command. The load command
will be converted to IGV position that
will be the same on each
compressor.
Balancing compressor load results in
the best overall efficiency and with
both circuits operating with nearly the
same refrigerant pressures.
When both compressors are running
the overall chiller load command will
be split evenly between the two
compressors unless limit control
overrides balancing. When
transitioning between one
compressor operation and two-
compressor operation, the load
commands will be actively balanced
at a rate slow enough to minimize
capacity control disturbances
Restart Inhibit
The purpose of restart inhibit feature
is to provide short cycling protection
for the motor and starter.
The operation of the restart inhibit
function is dependent upon two
setpoints. The Restart Inhibit Free
Starts (1-5, 3 default), and the Restart
Inhibit Start to Start Timer (10-30min,
20 default). These settings are
adjustable via the service tool.
Restart Inhibit Free Starts
This setting will allow a number of
rapid restarts equal to its value. If the
number of free starts is set to "1", this
will allow only one start within the
time period set by the Start to Start
Time Setting. The next start will be
allowed only after the start to start
timer has expired. If the number of
free starts is programmed to "3", the
control will allow three starts in rapid
succession, but thereafter, it would
hold off on a compressor start until
the Start to Start timer expired.
Restart Inhibit Start to Start Time
Setting
This setting defines the shortest
chiller cycle period possible after the
free starts have been used. If the
number of free starts is programmed
to "1", and the Start to Start Time
Setting is programmed to 20
minutes, then the compressor will be
allowed one start every 20 minutes.
The start-to-start time is the time from
when the motor was commanded to
energize to when the next command
to enter prestart is given.
Clear Restart Inhibit
A Clear Restart Inhibit "button" is
provided within Settings; Manual
Override on the DynaView display.
This provides a way for an operator
to allow a compressor start when
there is a currently active Restart
Inhibit that is prohibiting such a start.
The "button" press will have no
other function than to remove the
restart inhibit if there is one active. It
does not change the count of any
internal restart inhibit timers or
accumulators.
The restart inhibit function, setpoints
and clear features exist for each
compressor and operate
independently of other compressors
on that chiller.
During the time the start is inhibited
due to the start-to-start timer, the
DynaView shall display the mode
'Restart Inhibit' and the also display
the time remaining in the restart
inhibit.
A "Restart Inhibit Invoked" warning
diagnostic will exist when the
attempted restart of a compressor is
inhibited.
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