FRICK QUANTUM CONTROL PANEL
OPERATION
S90-010 O
Page 36
If the system Discharge Pressure is below the Condenser
Control setpoint the following is repeated until all condenser
outputs are turned off:
1. If the system Discharge Pressure continues to fall and
is less than or equal to the Condenser Control setpoint
minus the digital control lower dead band, then the last
condenser output that is on, is turned off. When a con-
denser output is turned off, the lower delay time is used
to set a timer that must time out before the next con-
denser output will be turned off.
Analog Condenser Control
The following is a description of the Condenser Control
logic when only analog Condenser Control is enabled.
If the system Discharge Pressure is above the Condenser
Control setpoint:
1. If the system Discharge Pressure is greater than or
equal to the Condenser Control setpoint plus the ana-
log control upper dead band, then condenser output
#4 is turned on (if it is not already on) and the analog
output signal is increased using the response time.
If the system Discharge Pressure is below the Condenser
Control setpoint:
1. If the system Discharge Pressure continues to fall and
is less than or equal to the Condenser Control setpoint
minus the analog control lower dead band, then the
analog output signal is decreased using the response
time. When the signal reaches its minimum output,
condenser output #4 is turned off.
Digital and Analog Condenser Control
The following is a description of the Condenser Control
logic when digital and analog Condenser Control is enabled.
If the system Discharge Pressure is above the Condenser
Control setpoint the following is repeated until all condenser
outputs are turned on:
If the system Discharge Pressure is greater than or equal to
the Condenser Control setpoint plus the analog control up-
per dead band, then condenser output #4 is turned on (if it
is not already on) and the analog output signal is increased
using the response time.
Note: Condenser output #4 must first be turned on be-
fore the other condenser digital outputs are allowed to
be turned on.
If the system Discharge Pressure is below the Condenser
Control setpoint the following is repeated until all condenser
outputs are turned off:
If the system Discharge Pressure continues to fall and is less
than or equal to the Condenser Control setpoint minus the
analog control lower dead band, then the analog output is
decreased using the response time. When all the condenser
outputs are off then condenser output #4 is turned off.
CONTROL SETUP - OPTIONS SETUP -
“Compressor Sequence Control”
(MODE 1) SCREEN
This screen is shown if it was selected as an option in Panel
Setup. For quick access to this screen there is a [Compres-
sor Sequence Setpoints] screen key on the “Operating
Status -2” screen. This sequencing is intended for compres-
sors that are operating to maintain the same Capacity Con-
trol setpoint. The settings on this screen are used to se-
quence the compressors when a compressor is in the re-
mote start mode of operation and in remote Slide Valve
mode and available to run (not in shutdown/cutout or Re-
cycle Delay). This sequence control is only used for com-
pressors with a variable Slide Valve and will work with ex-
isting Frick RWB, RXB, and RXF panels. Serial communica-
tion using the Com-1 port is used for this sequencing. See
wiring diagrams for Quantum multicompressor sequencing
(drawing nos. 640A0042 and 640A0050)
The setpoints that are currently being used for Capacity
Control are only shown here for referencing. These set-
points are taken from the active Capacity Control settings at
the panel where Compressor Sequencing is activated. “Cur-
rent Value” is the current or actual reading of the pressure
or temperature process variable that was chosen as the
Capacity Control method. Compressor Sequencing can be
enabled from panel setup and entered on more than one
panel. However, for proper control, only the Compressor
Sequencing settings at one panel should be made active.
The following describes how Compressor Sequencing uses
the Capacity Control setpoints:
Capacity Control - This is the reading which the control
sequence will attempt to maintain for the indicated process.
This setpoint is used to control the loading and unloading
of the compressors.
The Proportional Band setpoint determines a range of Capacity
Control values where proportionally timed pulsed output is used.
Beyond the proportional band the output is continuously ener-
gized. The length of time the output will be pulsed-on is proportional
to the distance from the “Current Value” to the Capacity 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 midway from set-
point, the output is on and off an equal amount of time. (See “Cycle
Time”).
Upper 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 proportional band. When in this band,
the control system will begin the process of starting
compressors. Previously started compressors must be
loaded greater than 90% slide valve before starting a
new compressor.
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