Operating Values; Sequencing - Johnson Controls FRICK QUANTUM LX Operation

ACCESSING:
DESCRIPTION: This screen will be available if Sequencing is enabled in Compressor confi guration. This is strictly a status
screen; no values can be changed from here.
The following is a description of the Sequencing strategy:
Start/Stop
System Setup:
• Control Input – Suction Pressure
• Control Direction – Forward
• High Stage Link – Disabled
Start Procedure
Before starting a compressor, the leader must
determine that all running compressors are load-
ed and that the Suction Pressure has risen to a
point where an additional compressor is needed.
First, the leader checks that either no compres-
sors are running or all the running compressors
average 90% capacity. If a running compressor is
at less than 90% capacity but is in a Load Inhibit
or Force Unload condition, for the purposes of
this calculation it is assumed to be at 90%
capacity.
If all the running compressors are loaded the
leader next begins comparing its Suction Pres-
sure to the Autocycle Start setpoint. When the
Suction Pressure rises above the Start setpoint,
the start timer is initiated. If the start timer
reaches the Autocycle Start Delay setpoint time
and the Suction Pressure has remained above
the Start setpoint for the entire time, the leader
QUANTUM™ LX COMPRESSOR CONTROL PANEL
OPERATION
OPERATING VALUES - Sequencing

Operating Values...

Sequencing

attempts to start an additional compressor. If the
Autocycle Start Delay setpoint is 0 minutes,
the leader still waits 15 seconds before
starting a compressor.
To determine which compressor to start, the
leader first sorts all the compressors in the sys-
tem based on their start number, low to high. If
two compressors have the same start num-ber,
the first one on the list remains ahead of the
second. Next, the leader starts at the top of the
list and works down through list until it finds a
compressor that is available to run. To be
deemed available, a compressor must have
good sequencing
Compressor Mode and Capacity Mode must be
set as Remote Sequencing. In addition the
compressor must be off, and it cannot be in a
Start Inhibit condi-tion except for the Start
Inhibit Slide Value Too High condition. The
compressor with the lowest start number that
also meets these conditions is then sent a start
command. If no compressors are currently
available to start, the leader will continue
checking until one becomes available or until
the Suction Pressure drops below the Start
setpoint.
After a compressor has been sent a start
com-mand,
compressor to reach a Running state. If 3
minutes passes and the compressor has not
yet begun to run, the leader sends it a stop
command. This com-
090.022-O (MAY 12)
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communications and
the leader waits for
its
that