144
JOHNSON CONTROLS
5276178-JIM-C-0118
Sequence of Operation
must be in the positions shown in Table 63.
TABLE 72 - VFD JUMPERS
JUMPER
60 HZ
50 HZ
J2
REMOVE
REMOVE
J3
REMOVE
REMOVE
J4
REMOVE
REMOVE
J5
MIDDLE
MIDDLE
J6
MIDDLE
MIDDLE
J7
IN
IN
J8
IN
IN
J9
IN FOR 60 HZ
REMOVE FOR 50 HZ
Potentiometer settings are also preset at the factory. The
potentiometers should be in the positions shown in Table
64. The potentiometers do not have numerical settings
and are set according to the positions indicated. DO
NOT change potentiometer settings unless they do not
match the positioning of the potentiometers shown in
Figure 66. Modifying these settings may cause damage
to the unit, control problems, and/or poor operating
efficiency.
TABLE 73 - POTENTIOMETER SETTINGS
P1
P2
350 PSIG
80 PSIG
6 O’CLOCK
6 O’CLOCK
P1
P2
P1
P2
FIGURE 71 - CONDENSER FAN VFD
POTENTIOMETER SETTINGS
LD11300B
operation,
“LOW AMBIENT PKG”
is turned ON for the
refrigerant system. In addition, the unit will have a VFD
installed to control the speed of the first condenser fan.
The VFD is located in the blower compartment above
the blower motor.
Operation and Pressure Control Range
The VFD controls the speed of the fan based on a
discharge pressure setpoint and a differential range.
When discharge pressure reaches approximately 270
PSIG, the VFD will start the fan if the Unit Controller
is calling for compressor / condenser fan operation.
As soon as the 6M contactor is energized, the VFD will
be activated and will begin to control. As the pressure
rises over the next 80 PSIG (270 to 350 PSIG), the fan
speed will increase to full speed at approximately 350
PSIG.
The VFD control input signal originates from the
discharge pressure transducer for the compressor system
it is controlling. The transducer signal feeds the VFD.
The VFD controls the fan speed based on discharge
pressure.
Configuration (Jumpers and Potentiometers)
The inverter is configured at the factory. The jumpers
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