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Scholar V VAIVA Maintenance & Service Manual 10/2017 Rev.2
5. SCREEN 5:
Control Voltages and Settings
(Changes require username/password)
a. Max Comp. Volts (cooling):
The compressor speed is controlled by applying a
DC control voltage to the compressor driver board. This value is the maximum DC
voltage that the PLC will deliver to the driver board in the cooling mode.
b. Max Comp. Volts (heating)
: The compressor speed is controlled by applying a
DC control voltage to the compressor driver board. This value is the maximum DC
voltage that the PLC will deliver to the driver board in the heating mode.
c. Min. Comp Volts
: This value is the minimum control voltage that the PLC will
deliver to the compressor driver in any mode.
d. V or -
: The compressor speed is matched to the room load by increasing
or decreasing the speed until the room temperature moves into the control band
(explained in Screen 5). The compressor speed is changed by incrementing or
decrementing the control voltage by a small amount at a specified time interval
until the room conditions move into the control band. Once the temperature is in-
side the control band, the speed control voltage remains fixed until the temperature
again moves outside the band.
e. + or – Time (sec)
: This is the time increment that elapses between compressor
control voltage changes (incrementing or decrementing).
f. Maximum Blower Volts
: The indoor blower is an electronically commutated
device that is controlled by a 0 – 10 VDC signal generated by the PLC. The PLC
modulates the control voltage based on the compressor speed to try and maintain
a relatively constant evaporator temperature in cooling and a relatively constant
condenser temperature in heating. This parameter is the maximum voltage the
PLC will deliver to the motor controller.
g. Minimum Blower Volts
: The indoor blower is an electronically commutated device
that is controlled by a 0 – 10 VDC signal generated by the PLC. The PLC modu-
lates the control voltage (blower speed) based on the compressor speed to try and
maintain a relatively constant evaporator temperature in cooling and a relatively
constant condenser temperature in heating. This parameter is the minimum volt-
age the PLC will deliver to the motor controller
h. Forward
: Press once to go to the next screen.
i. Back
: Press once to go to the previous screen
j. Back to Main
: Press once to go back to Main Screen
