Emerson Vilter MicroVission - Condenser Control Set Points

21 – 2
Section 21 • Condenser Control
MicroVission Controller • Operation and Service Manual • Emerson • 35391MV 1.3
Condenser Control Set points
Run Mode
Run Mode allows the selection of different modes of op-
eration for condenser control. The choices for selection
are:
Run Never
The mode of operation by default. Condenser Control
operation will not be performed when this mode is
active.
Run With Comp
Automatic operation of condenser control selected
when control of the condenser is required to only run
when the compressor is running.
Run Always
Automatic operation of condenser control selected
when control of the condenser is required to run even
when the compressor is off.
Manual
Mode for controlling condenser operation manually.
Operator controls the operation by manual stepping us-
ing an on/off toggle button at each step.
Condenser Pressure:
This is a read only parameter and it displays the present
value of condenser pressure.
Condenser Setpoint
This is the condenser pressure setpoint that needs to be
maintained.
Upper Deadband
This is the condenser pressure setpoint, upper dead-
band value. No additional condenser capacity is added
when the condenser is selected for automatic step
control and the condenser pressure falls within this
dead-band.
Lower Deadband
This is the condenser pressure setpoint, lower dead-
band value. Condenser capacity is not reduced when the
condenser is selected for automatic step control and the
condenser pressure falls within this dead-band.
Ambient Temp
This is a read-only parameter and it displays the pres-
ent value of ambient temperature. This is displayed only
when Ambient Sensor is enabled from Conguration
Screen.
Summer/Winter Auto Switch
This checkbox, when enabled, allows proles to switch
automatically depending on the ambient temperature
setpoint when Run Mode is “Auto”. When ambient tem-
perature falls below the ambient temperature setpoint,
winter prole is used. Similarly when ambient tempera-
ture is above the ambient temperature setpoint, sum-
mer prole is used.
Switch Temp
This is the ambient temperature setpoint used for auto-
matic switching of prole from summer to winter and
vice-versa.
High-Low Speed Fan Delay
This is a time delay for the fan spin down in case of 2-
speed motor/dual speed fan.
VFD Settings
This section is active only when Condenser VFD is not set
to None in the Conguration Screen. When a VFD Fan is
used for condenser control operation, the speed of the
VFD is controlled using PID algorithm.
P = Proportional (gain)
Used to adjust the fan speed action in direct proportion
to the difference between the control setpoint and the
process variable (SP - PV = error). The proportional term
is a unitless quantity and is used for coarse adjustment.
This setpoint should be set to the lowest value that gives
adequate control system response. Increasing the pro-
portional setting increases the control system’s sensi-
tivity to small process uctuations and the tendency to
hunt.
I = Integral (reset)
Used to adjust the capacity control action, integrating
the error over time, to account for a small error that has
persisted for a long time. This quantity is used for ne
adjustment. This setpoint is used to smooth out process
variations. This setpoint should be set high enough to
prevent hunting but not too high or it will cause control
system overshoot.
D = Derivative (rate)
Used to adjust the capacity control action, accounting for
how fast the error is changing, positively or negatively.
Maximum Speed
This setpoint denes the maximum speed in percentage
for Condenser VFD Fan at which it should run for con-
tinuous step delay time to increase condenser steps. E.g.
let’s say setpoint is kept at 95%. Then condenser VFD fan
will have to run at speed of 95% or more to advance to
next step. Maximum Speed can be set as 100%, which is
when analog output (at which condenser VFD fan is con-
nected) reaches to 20mA in its normal range of 4-20 mA.
Minimum Speed
This setpoint denes the minimum speed in percentage
for Condenser VFD Fan at which it should run for contin-
uous step delay time to decrease condenser steps. E.g.
let’s say setpoint is kept at 5%. Then condenser VFD fan
will have to run at speed 5% or less to advance to next
step. Minimum Speed can be set as 0%, which is when
analog output (at which condenser VFD fan is connect-
ed) reaches 4mA in its normal range of 4-20 mA.