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FORM 150.67-NM2 (209)
167
JOHNSON CONTROLS
8
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 385 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, assuring superheat
and oil control is not compromised. When the chiller and
VFD fan control points are programmed properly, the fans
will operate as outlined in Table 26
FAN STAGE
ON
OFF
CONTACTOR
MICROBOARD
FAN #
SYS 1
SYS 1
SYS 1
1:
VFD Control
(1 fan
Variable Speed)
Fan Speed
Is A Function Of
Liquid Temperature
Fan will turn on when
liquid line temperature
is above 65
º
F. Speed
increases with
temperature,
FAN Will Turn OFF
When Liquid
Temperature Drops
Below 65 °F
7M
TB7-3
1
2:
1 Fan VFD
Control
2nd Fan
Full Speed
Under Contactor
Control
385 PSIG,
Both Fans
Will Be Running Full
Speed
Discharge
Pressure
< 260 PSIG (Pressure Is
< Fan Control ON Pres-
sure of
385 PSIG Minus Fan
Differential
Pressure of 125 PSIG =
260 PSIG)
Fan 1 Will Still
Be Running
7M & 8M
TB7- 3
&
TB7-10
1 & 3
TABLE 23 –
YCAL0019 – 0028 VFD LOW AMBIENT OPTION – CONDENSER FAN CONTROL OPERATION
YCAL0019 – 0028
Содержание YCAL0019
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