Figure 49 - Typical Vfd Enclosure Locations; Table 24 - Ycal0019 - 0028 Vfd Low Ambient Option - Condenser Fan Control Operation; Programming - Ycal0019 – 0028 - York YCAL0019 Installation, Operation And Maintenance Manual

SECTION 8 – UNIT OPERATION
TABLE 24 - YCAL0019 – 0028 VFD LOW AMBIENT OPTION – CONDENSER FAN CONTROL OPERATION
FAN STAGE
IS A FUNCTION OF
1: LIQUID TEMPERATURE
VFD CONTROL FAN WILL TURN ON
(1 FAN WHEN LIQUID LINE
VARIABLE TEMPERATURE IS
SPEED) ABOVE 65º F. SPEED
INCREASES WITH
TEMPERATURE,
2:
1 FAN VFD
CONTROL
2ND FAN
FULL SPEED WILL BE RUNNING
UNDER
CONTACTOR
CONTROL
PROGRAMMING - YCAL0019 – 0028
Condenser fan control type must be programmed un-
der both the OPTIONS and PROGRAM keys when a
VFD is installed on the chiller. Under the OPTIONS
key, FAN CONTROL must be programmed for DIS-
CHARGE PRESSURE CONTROL only. This will as-
sure 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 PRES-
SURE 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 opti-
mum control of the fans at reduced ambient tempera-
tures, assuring superheat and oil control is not compro-
mised. When the chiller and VFD fan control points
are programmed properly, the fans will operate as out-
lined in Table 24.
192
ON
FAN SPEED
FAN WILL TURN OFF
TEMPERATURE DROPS
< 260 PSIG (PRESSURE
385 PSIG, < FAN CONTROL ON
BOTH FANS PRESSURE OF
385 PSIG MINUS FAN
FULL SPEED DIFFERENTIAL
PRESSURE OF 125 PSIG
FAN 1 WILL STILL
CONTACTOR
OFF
WHEN LIQUID
BELOW 65 °F
DISCHARGE
PRESSURE
IS
= 260 PSIG)
BE RUNNING
YCAL0033 Low Ambient Fan Control Option
General
The low ambient option consists of a VFD (Variable
Frequency Drive) that controls the speed of the first fan
(Fan 1) in the fan staging sequence. The VFD is locat-
ed on the top of chiller above the compressor section.
Examples of the typical VFD location and enclosure
mountings are shown in Figures 49 and 50.
VFD Enclosure Location

FIGURE 49 - TYPICAL VFD ENCLOSURE LOCATIONS

FORM 150.67-NM1
ISSUE DATE: 4/28/2017
MICROBOARD
SYS 1 SYS 1
7M TB7-3
TB7- 3
7M & 8M &
TB7-10
JOHNSON CONTROLS
FAN #
SYS 1
1
1 & 3
LD12080