Emerson VILTER MicroVission Operation And Service Manual page 59

Section 5 • Compressor Control
Low Suction Pressure
• When the suction pressure value is equal to or less
than this setpoint, algorithm will not allow loading
of the compressor. However, if the suction pressure
value exceeds this setpoint, algorithm will allow
loading of the compressor.
High Motor Current
• When the motor current value is equal to or greater
than this setpoint, algorithm will not allow loading
of the compressor. However, if the motor current
value drops below this setpoint, algorithm will allow
loading of the compressor.
Force Unload Setpoints
High Suction Pressure
• When the suction pressure value is equal to or great-
er than this setpoint, algorithm will unload the com-
pressor by one step. Algorithm will continue unload-
ing the compressor step-by-step to minimum load
until the suction pressure value drops below this
setpoint.
High Discharge Pressure
• When the discharge pressure value is equal to or
greater than this setpoint, algorithm will unload the
compressor by one step. Algorithm will continue un-
loading the compressor step-by-step to minimum
load until the discharge pressure value drops below
this setpoint.
Figure 5-10. Compressor Control Screen - Load Limiting
MicroVission Controller • Operation and Service Manual • Emerson • 35391MV 1.3
Low Suction Pressure
• When the suction pressure value is equal to or less
than this setpoint, algorithm will unload the com-
pressor by one step. Algorithm will continue un-
loading the compressor step-by-step to minimum
load until the suction pressure value exceeds this
setpoint.
High Motor Current
• When the motor current value is equal to or greater
than this setpoint, algorithm will unload the com-
pressor by one step. Algorithm will continue un-
loading the compressor step-by-step to minimum
load until the motor current value drops below this
setpoint.
Unload Timer
• This is the time duration that force unload algo-
rithm will use while unloading each step during
the force unload condition. For example, when the
suction pressure value is equal to or greater than
the "High Suction Pressure" Force Unload setpoint,
the algorithm will unload one step and wait for the
time as defined by this setpoint. Once the time set is
lapsed, the algorithm will check again if the suction
pressure value is equal to or greater than the "High
Suction Pressure" Force Unload setpoint. If yes, the
algorithm will unload one more step.
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