FRICK QUANTUM CONTROL PANEL
OPERATION
S90-010 O
Page 41
controller attempts to maintain the Capacity Control set-
point by loading and unloading in response to the following
capacity control setpoints. The Follower compressor
sequence controller is signaled from a previous panel to
load or un-load and then uses the following Capacity
Control setpoints to determine when to pulse the panel’s
local Slide Valve load and Slide Valve unload outputs. The
signal for loading or unloading from the previous panel
overrides the Follower's Capacity Control settings that
might be determining the op-posite local Capacity Control.
For example, the Follower's local settings could indicate it
should be loading, but a signal from a previous panel
could be telling it to unload. In this situation the Follower
will unload, but it will pulse according to its local settings.
The Follower's local settings are used to de-termine pulse
loading or unloading and if these settings don’t coincide
with the Leader's settings, then improper pulsing can
result. For good Capacity Control, it is impor-tant that
each panel is properly set up. The following de-scribes
the compressor sequencing Capacity Control
setpoints:
• C
apacity Control - This is the reading which the Leader
compressor sequence controller will attempt to main-
tain. This setpoint at each panel is used to control the
loading and unloading of the compressor.
The Proportional Band setpoint determines a range of ca-
pacity control values where pulsed output is used. Beyond
the proportional band the output is continuously energized.
The length of time the output will be pulsed on is propor-
tional to the distance the actual reading is from the Capac-
ity Control setpoint. The further the distance from setpoint,
the longer the output is pulsed on and the shorter the output
is off. The closer the distance to setpoint, the shorter the
output is pulsed on and the longer the output is off. If the
actual reading is midpoint from setpoint, the output is on
and off an equal amount of time.
• U
pper Proportional Band - A band, measured in
the units of the capacity control setpoint, above
the upper dead band, where proportional load
control is used. If the actual reading rises into this
proportional band, the load output will be pulsed
as explained above in the description about pro-
portional band. When in this band, the Leader
compressor sequence controller will begin the pro-
cess of starting the compressor.
• Lower Proportional Band - A band, measured in
the units of the Capacity Control setpoint, below
the lower dead band, where proportional unload
control is used. If the actual reading falls into this
proportional band, the unload output will be pulsed
as explained above in the description about pro-
portional band.
• Upper Dead Band - A band, measured in the units of
the Capacity Control setpoint, above the setpoint at
which the compressor will neither load nor unload.
• Lower Dead Band - A band, measured in the units of
the Capacity Control setpoint, below the setpoint at
which the compressor will neither load nor unload.
• Control Type:
• Leader - The panel is selected as the Leader for
compressor sequencing control. The Leader is able
to control one or more subsequent Followers.
• Follower - This panel is selected as a Follower for
com-pressor sequencing control. The Followers
will be controlled by the setpoint of the Leader.
• Slide Valve Pos. - The actual % reading of the Slide
Valve position.
• Slide Valve Status - One of the following could be shown:
• Load - Indicates the compressor is being told to
load.
• Unload - Indicates the compressor is being told to
unload.
• Idle - Indicates the compressor is neither being
told to load or unload.
• Sequence Status - One of the following text strings
could be shown:
• Off in Remote Start
• Off in Manual Start
• Off in Autocycle Start
• Off in Recycle Delay
• Shutdown
• Running in Remote Start
• Running in Manual Start
• Running in Autocycle Start
• Not in Remote Start
• Slide Valve not in Remote
• Output Status (Digital Board 2):
• Start (Output 1) - This output is energized to signal
the next panel to start the compressor. This output
is de-energized to signal the next panel to stop the
compressor.
• Capacity Up (Output 2) - This output is energized
to signal the next panel to load the compressor.
• Capacity Down (Output 3) - This output is ener-
gized to signal the next panel to unload the com-
pressor.
• Slide Valve > Minimum (Output 8) - This output is
energized to signal the previous panel that the
Follower's slide valve reading is above the
“Minimum Capacity when Running” setpoint.
• Input Status (Digital Board 2):
• Start (Input 5) - This input is energized to signal
this panel to start the compressor. This input is de-
energized to signal this panel to stop the com-
pressor.
• Capacity Up (Input 6) - This input is energized to
signal this panel to load the compressor.
• Capacity Down (Input 7) - This input is energized
to signal this panel to unload the compressor.
• Slide Valve > Minimum (Input 4) - This input is en-
ergized to signal this panel that the Slide Valve
reading of the next compressor is above that panel’s
“Minimum Capacity when Running” setpoint.
The active capacity control setpoints are shown here for
referencing. The active Capacity Control setpoints are taken
from the Capacity Control settings at this panel. “Actual” is
the current reading of the pressure or temperature that was
chosen as the Capacity Control setpoint. For proper con-
trol, only one panel should be selected as the Leader for
compressor sequencing. The Leader compressor sequence
To Next Page
Loading...
