Emerson VILTER MicroVission Operation And Service Manual page 63

Section 5 • Compressor Control
• Compressor will load/unload as per Pumpdown
Stop Pressure Setpoint. i.e. Pumpdown Stop
Pressure setpoint will act as Control setpoint in-
stead of Suction Pressure Control Setpoint.
• The compressor will be placed into "Stop" mode
after the suction pressure is equal to or goes be-
low the Pumpdown Stop Pressure setpoint.
Pumpdown:
• This checkbox enables the Pumpdown feature. If this
box is unchecked, the Pumpdown setpoints are ig-
nored and the user is not allowed to edit them.
Stop Pressure:
• This setpoint defines the suction pressure value at
which the compressor will cycle off. Normally, this
setpoint is set below the Suction Pressure Auto-cycle
Stop Pressure setpoint.
Stop Delay:
• This setpoint delays the compressor from stopping
when the suction pressure is equal to or less than the
Stop Pressure.
MicroVission Controller • Operation and Service Manual • Emerson • 35391MV 1.3
Pumpdown Operation (Run/Stop):
• This button starts/stops the Pumpdown operation.
This button is active only when compressor is in Local
Auto run mode and the Control Mode configured is
Suction Pressure. This button will display "Run" when
Pumpdown operation has not started or stopped,
while button will display "Stop" when Pumpdown op-
eration is running.
When the Pump down feature is enabled, the Pulldown
checkbox is automatically grayed out. Similarly, when
Pulldown feature is enabled, the Pumpdown checkbox
is automatically grayed out and hence, the user will not
be able to operate the Pumpdown feature. This is done
to keep the Pumpdown and Pulldown features mutually
exclusive.
If the Pumpdown Operation is running and the
Control Mode is changed to Process Control, then
the Pumpdown Operation will wait till the control
mode is changed back to Suction Pressure, and till
then the Process Control Setpoint will be used to
load/unload the compressor, not the Pumpdown
Stop Pressure Setpoint. Also, If the Control Mode
is changed while Pumpdown is running, the
Pumpdown Operation will stop running.
NOTE
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