RXB PLUS ROTARY SCREW COMPRESSOR UNITSS70-101 IOM
Page 22
OPERATION
TEMPERATURE-PRESSURE CONTROL
PROGRAM (OPTION)
NOTE: The following displays are provided only when
the Temperature-Pressure Control Program option has
been ordered with the RXB Plus Rotary Screw Compres-
sor Unit.
SETPOINTS DISPLAY, Page 1 *
SETPOINTS PAGE 1 Capacity Control=Press
C.C. CUTOUT ALARM PB DB CT
Press 25.3g 01.3g 05.3g 10 1.0 10
Temp +40.0F +32.0F +33.0F 10 0.5 10
The Setpoints Display is accessed by pressing the
[CHANGE] key.
CONTROL - This setpoint is used to select either Pressure
Capacity Control or Temperature Capacity Control. NOTE:
There are only two setpoints, press for pressure capac-
ity control and temp for temperature capacity control.
CC - The capacity control setpoint is for normal operation,
not setback.
CUTOUT -This setpoint will stop the compressor if the suc-
tion pressure drops below the pressure setpoint for 90 sec-
onds or if the CC Temperature drops below the temperature
setpoint. There is no time delay on the temperature cutout.
ALARM - An alarm will be activated if the suction pressure
drops below the pressure setpoint or if the CC Temperature
drops below the temperature setpoint. There is no time de-
lay for either.
NOTE: Lo Temp Cutout and Alarm are active when op-
erating in temperature capacity control mode only.
These are failures based on the controlling temperature
input. They precede the auxiliary failures on the annun-
ciator display.
PB - The Proportional Band (PB) is used to determine the
amount of time the load/unload solenoid is energized, ac-
cording to how far away from the setpoint the actual control
pressure or temperature is. The smaller the number, the more
load/unload will be sent. A PB of 10% is default. It is adjust-
able to 2, 5, 10, 15, 20, or 25 percent.
DB - The Dead Band (DB) is a + (plus) or - (minus) value
above or below the setpoint which the compressor will nei-
ther load nor unload. It is adjustable between .5 and 5.0
psig or degrees, in increments of .5 units.
CT - The Cycle Time (CT) setpoint is the amount of time
between the beginning of each load/unload response. It is
adjustable to 5, 10, 15, 20, 25, or 30 seconds.
Use the [STEP] key to step to the desired setpoint, then
press the [CHANGE] key to change the CC, PB, DB, and
CT values. Enter the desired value for the remaining
setpoints and press [ENTER] when complete.
SETPOINTS DISPLAY, Page 2
Refer to “SETPOINTS DISPLAY” (SETPOINTS PAGE 2) on
page 17 and “SETPOINTS DISPLAY, Page 2:” on page 18.
* Display for illustrative purposes only.
SETPOINTS DISPLAY, Page 3*
SETPOINTS PAGE 3 ID=[02] [04-09-90]
offset-act Mon [01:00:18]
Sup Heat-Alarm-10F-no Baud-[19200]
Sep Cond-Alarm-10F-no Recycle--[30]
The new setpoints provided on this display allow monitoring
of compressor superheat and condensing in the separator.
The following setpoints apply to the monitoring of the super-
heat and condensing in the separator.
ALARM/(SHUTDOWN) - The Alarm/(shutdown) setpoints
select the conditions for an alarm or shutdown. If alarm is
selected, the alarm will occur after a 30 second delay. If
shutdown is selected, the shutdown will occur 60 seconds
after the alarm. NOTE: The Superheat Cutout and Alarm
follow the auxiliary failures on the annunciator display
of the TEMPERATURE-PRESSURE CONTROL PRO-
GRAM option. The Sep Cond Alarm and Cutout are new
failure features and are currently the last two listed in
the Annunciator Display for the TEMPERATURE-PRES-
SURE CONTROL program option.
OFFSET - This setpoint is the degrees F above the satura-
tion-point temperature where the alarm or shutdown will oc-
cur.
ACT - The function selects whether the alarm/shutdown is
activated or not.
SETPOINTS DISPLAY, Page 4*
SETPOINTS PAGE 4 Active When Running in
Temperature Cap. Cont.
Low Suction Press Stop Load------------- [05.0g]
Low Suction Press Force Unload -------- [00.0g]
Low-suction-pressure and motor-load-control features were
added to the TEMPERATURE-PRESSURE CONTROL pro-
gram and placed on this display. They are active only while
the compressor is operating in Temperature Capacity Control
Mode. The two new setpoints are Low Suction Press Stop
Load and Low Suction Press Force Unload. Both are entered
as a pressure in gauge or inches of mercury (HG). When suc-
tion pressure reaches the stop-load setpoint, loading of the
compressor is inhibited. When the suction reaches the force-
unload setpoint, the compressor will unload until the suction
pressure is greater than the force-unload setpoint. Control
will then be released to allow normal operation.
SETPOINTS DISPLAY, Pages 5 and 6
Refer to “SETPOINTS DISPLAY” (FIXED PAGES 1 & 2) on
page 17 and “SETPOINTS DISPLAY, Fixed, Pages 1 and
2:” on page 19.
Use the [STEP] key to step to the desired setpoint, then
press the [CHANGE] key to change it. Press [ENTER] when
all desired setpoint changes have been made.
SETBACK DISPLAY *
SETBACK DISPLAY: Mon 04-09-90 01:00:51
Press Setpt-[25.3g] Temp Setpt[+50.0F]
Active-[No ] Mon Start Time-[- -:- -]
F1 to Exit Stop Time-[- -:- -]
The Setback Display is accessed by pressing the [F3] key.
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