Fan Control For The Remote Air Cooled Condenser - Trane RTWD Installation Operation & Maintenance

Fan Control for the Remote Air Cooled
Condenser
The CH530 Controls for the RTUD compressor chiller
provide as an option, the fl exible and full control of
2-circuit remote air cooled condenser fans. In addition
to the option for controlling between 2 to 8 fi xed
speed fans per circuit (or multiples thereof), a separate
additional option includes the ability to control either
two speed fans or variable speed fan/drive combinations
in conjunction with other fi xed speed fans, to provide
low ambient outdoor air temperature capability. The
controls will also provide an option for a simple per
circuit interlock output (in lieu of actual fan control)
to use in the scenario in which independent fan head
pressure or differential pressure controls (by others) is
applied. It is recommended however, that for the best
overall unit performance, the integral fan control option
is selected.
The controls support control of a remote, air cooled
condenser fan deck, from 2 to 8 fans per circuit (1-8 fans
for variable speed). It supports options to control
the following types of standard ambient outdoor air
temperature fan decks: 1) all fans fi xed speed, and 2) all
fans two speed. It will also support the following low
ambient outdoor air temperature fan decks 1) one fan
per circuit is Two-Speed, (remaining fans fi xed speed),
and 2) One fan per circuit is variable speed i.e. variable
frequency drive (VFD), (remaining fans fi xed speed). In
the variable fan low ambient outdoor air option the VFD
fan and fi xed speed fans are sequenced accordingly to
provide continuous control from 0-100% air fl ow per
circuit. Fan staging provides the correct combination of
fi xed speed fan relay, VFD relay (to enable operation of
the VFD), and speed outputs to provide air fl ow control
commanded by the fan algorithm running inside the
CH530 Main Processor. The fan deck arrangement is
independently confi gurable per circuit.
RLC-SVX14H-GB
Split system installation
Since the condenser is provided separately from the
RTUD compressor chiller, the RTUD electrical panel
design does not provide for condensing unit's control
power requirements. The chiller's control power
transformer is not sized to provide the control power for
the additional fan contactor loads. The CH530 controls,
when properly optioned, will provide for pilot duty
rated relays, low voltage binary inputs, and low voltage
analog outputs to control the remote contactors and
inverters provided by others. The CH530 fan control
relays located in the chiller control panel, are intended
to control the fan contactors that are located in the
remote air cooled condenser panel. The Fan Control
Relays are rated for up to 7.2 Amps resistive, 2.88
Amps pilot duty 1/3 HP, 7.2 FLA at 120 VAC, and up to
5 Amps general purpose at 240 VAC. All wiring for the
fi eld connections to the condenser, will have screw
terminals for termination in the RTUD control panel with
the exception of the outdoor air temperature sensor
(addressed above). Refer to the wiring diagrams.
Separate fan control algorithms are used for fi xed speed
and variable speed systems. For the variable speed
fan deck option, the fan control reverts to fi xed speed
control if an inverter drive fault is detected through a
binary input interface with the drive. An informational
diagnostic is also provided to indicate the issue.
For more fan control information, reference "Controls
Interface" chapter sections.
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