RWB II PLUS MICROPROCESSOR CONTROL
OPERATION
S70-200 OM
Page 12
be greater than or equal to the “START” setpoint in order to
start the compressor. This setpoint works in conjunction with
the “TIMER” setpoint located to the right of it on the display.
(Start) TIMER - This is a time delay used to start the com-
pressor. The timer only accumulates time whenever the CC
Temperature rises to or above the “START” setpoint and will
reset if the CC Temperature drops below the “START”
setpoint.
COMP STOP - The CC Temperature must be less than or
equal to the “STOP” setpoint in order to stop the compres-
sor. This setpoint works in conjunction with the “TIMER” set-
point located to the right of it on the display.
(STOP) TIMER - The (stop) TIMER is a time delay used to
stop the compressor. The timer only accumulates time when-
ever the CC Temperature drops to or below the “STOP” set-
point and will reset if the CC Temperature rises above the
“STOP” setpoint.
MINIMUM SLIDE VALVE - Minimum Slide Valve Position,
shown as a percentage, will limit the slide valve position to
the displayed setpoint.
ACTIVE - Indicates whether Auto Cycle is active or not. Press
the [CHANGE] key while at this setpoint to change the sta-
tus. Upon deactivation, the compressor will return to the
previous mode of operation.
LEAD-LAG OPTION
The lead-lag compressor sequencing option provides the
controls for operating two RWB II compressors in one system.
AUTO CYCLE DISPLAY *
AUTO CYCLE Tue 04-10-90 08:44:57
DISPLAY: Press F1 To Exit
Suction Pressure--------[06.5 g ]
Comp Start - [99.0 g } Timer—[00 min]
Comp Stop— [29.0 hg] Timer—[00 min]
Min SV———[50%] Lead—[YES]
Active———[No ]
*Display for illustrative purposes only.
The software includes user adjustable setpoints on the Auto
Cycle setpoints screen (F4 on Main Menu) for the following:
START - The suction pressure must be greater than or equal
to the “START” setpoint in order to start the compressor.
This setpoint works in conjunction with the “Timer” setpoint
located to the right of it on the Auto Cycle setpoints screen.
TIMER - This is a time delay used to start the compressor.
The timer only accumulates time whenever the pressure rises
to or above the “START” setpoint and will reset if the pres-
sure drops below the “START” setpoint.
STOP - The suction pressure must be less than or equal to
the “STOP” setpoint in order to stop the compressor. This
setpoint works in conjunction with the “Timer” setpoint lo-
cated to the right of it on the Auto Cycle setpoints screen.
TIMER - This is a time delay used to stop the compressor.
The timer only accumulates time whenever the pressure
drops to or below the “STOP” setpoint and will reset if the
pressure rises above the “STOP” setpoint.
MIN SV -This setpoint is the minimum slide valve position,
shown as a percentage, it will limit the slide valve position to
the displayed setpoint.
LEAD - This setpoint assigns the compressor as the lead or
the lag unit. Press the [CHANGE] key while at this setpoint
to change the status.
ACTIVE - This setpoint indicates whether the Auto Cycle
Mode is active or not. Press the [CHANGE] key while at this
setpoint to change the status.
OPERATION
For operation of the LEAD-LAG sequence, both units must
be in Auto Cycle compressor mode, one compressor micro
selected as the LEAD compressor, the other compressor
selected as the LAG compressor and the slide valves in Auto
mode.
With NO Compressor Running
The lead will start when its “START” setpoint is reached for
the amount of time selected for the “TIME” setpoint.
With ONE Compressor Running
If the load rises:
The lag compressor will start when its “START” setpoint is
reached for the amount of time selected for the “TIME” set-
point and the lead compressor is running at 100% slide valve
or running with the motor load inhibit or lead cutout or lead
in recycle.
If the load falls:
The lead compressor will stop when its “STOP” setpoint is
reached for the amount of time selected for the “TIME”
setpoint.
With TWO Compressors Running
If the load rises:
The lead and lag compressor will load independently.
If the load falls:
The lag compressor will unload to its “MIN SV” setpoint. Then
the lead compressor will unload to its “MIN SV” setpoint.
The lag compressor will stop when the suction pressure
drops below the “STOP” setpoint for the amount of time se-
lected for the “TIME” setpoint.
NOTE: Be careful not to select both compressors as lead
compressors or as lag compressors as improper op-
eration will result.
NOTE: One compressor will operate as a normal auto
cycle compressor when any one of the following occurs:
a. Power is removed from one of the two compressors,
b. Either of the compressors is NOT selected to “AUTO”,
or
c. If communications is lost between the compressors for
any reason.
