Emerson Vission 20/20, Operation And Service Manual

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Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 2.0
Section 6 • Compressor Control
Figure 6-9. Compressor Control Screen - Misc. 1 (Control Mode)
Control Mode
This drop down box gives the operator the ability to
change the type of control mode such as suction pres-
sure control or process temperature control. The opera-
tor can also switch from setpoint 1 and setpoint 2 for
each control method. What is available in this dropdown
box is dependent on the number and type of control
selected in the con
fi guration screen, see Figure 6-9.
Compress Control Screen - Misc 1 (Control Mode).
Stop Load and Force Unload
The stop load and force unload feature’s primary pur-
pose is to attempt to prevent the compressor from
tripping off due to particular instrument reading. For
example, if the suction pressure drops too low, the com-
pressor will trip off for safety reasons. However, the stop
load & force unload algorithm recognizes a potential trip
and either stops the compressor from loading up or even
unloads the compressor to prevent the trip.
Stop load:
• When this value is reached, the capacity slide will not
advance in any condition.
Force Unload:
• When this value is reached, the capacity slide posi-
tion will decrease until the variable reading is below
this value.
High Motor Amps:
• Motor current values for stop load and force unload.
High Discharge Pressure:
• Discharge pressure value for stop load and force
unload.
Low Suction Pressure:
• Suction pressure values for stop load and force unload