Emerson Vission 20/20 Operation And Service Manual page 51

Section 6 • Compressor Control
and the operator is not allowed to edit Pulldown
setpoints.
Initiate Pulldown at Next Start:
• This checkbox when enabled, turns on the Pulldown
process at the next start cycle, Pulldown operation
will work in the following manners:
• Pulldown only works when Control mode is
Suction Pressure 1.
• If not started in Suction Pressure 1 then
Pulldown process will not run until stopped and
restarted in Suction Pressure 1.
• If started in Suction Pressure 1 and changed
after start, then Pulldown process will be sus-
pended and restart once Control mode is
changed back to Suction Pressure 1.
Step Pressure:
• This setpoint defi nes the step decrements at which
the suction pressure value will be controlled at.
Delay Per Step:
• This setpoint defi nes the time increment at which the
compressor will be controlled at each step.
Stop Pressure:
• This setpoint defi nes the suction pressure value at
which Pulldown operation will get completed. When
suction pressure value is equal to or goes below
this setpoint, Pulldown feature disables itself. Also
"Pulldown" and "Initiate Pulldown at Next Start"
checkboxes will be automatically deselected as nor-
mally this is one time use feature.
Auto Cycle Differential:
• This setpoint defi nes the offset pressure values for
Auto Cycle Start Pressure and Stop Pressure from the
Suction Pressure setpoint. Auto Cycle Start Pressure
setpoint will be Suction Pressure setpoint increment-
ed by this setpoint pressure value, while Auto Cycle
Stop Pressure value will be Suction Pressure setpoint
decremented by this setpoint pressure value.
When Pulldown feature is enabled, Pumpdown checkbox
is automatically grayed out. Similarly when Pumpdown
feature is enabled, Pulldown checkbox is automatically
grayed out and hence, the user will not be able to op-
erate Pulldown feature. This is done to keep Pulldown &
Pumpdown features mutually exclusive.
Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 2.0
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