FORM 150.67-NM2 (209)
173
JOHNSON CONTROLS
8
P1
P2
P1
P2
POTENTIOMETER SETTINGS
P1
P2
292 PSI
32 PSI
Wiring
VFD wiring is simple and requires only 3-phase power
in, 3-phase power out, and a 2-wire signal from the
transducer. No start, stop, or other alternate power
requirements are needed to run the VFD. Fig’s 33 and
34 show the power and control wiring schematically
as well as the actual connections. The VFD controlled
fan will operate whenever the liquid line solenoid on
the respective system is energized.
PROGRAMMING
Condenser fan control type must be programmed
under both the OPTIONS and PROGRAM keys when
a VFD is installed on the chiller. Under the OPTIONS
key, FAN CONTROL must be programmed for
DISCHARGE PRESSURE CONTROL only. This will
assure condenser fan control of the chiller is solely by
discharge pressure, with no ambient control.
Under the PROGRAM Key, the FAN CONTROL ON
PRESSURE should be programmed for 425 PSIG
and the FAN DIFFERENTIAL OFF PRESSURE
must be programmed for 125 PSIG.
Programming as suggested assures the chiller control
points for the second fan in the fan staging sequence
and the inverter control points are matched for optimum
control of the fans at reduced ambient temperatures.
When the chiller and VFD fan control points are
programmed properly, the fans will operate as outlined
in Table 25.
FIG. 34 –
POTENTIOMETER SETTINGS
FIG. 33 –
INVERTER POWER WIRING SCHEMATIC
150A
L1
T1
150
151A
L2
T2
151
152A
L3
T3
152
CONDENSER
FAN NO. 1
SPEED
CONTR.
7M
250A
L1
T1
250
251A
L2
T2
251
252A
L3
T3
252
CONDENSER
FAN NO. 2
SPEED
CONTR.
10M
LD11300a
LD11301
Summary of Contents for YCAL0019
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