Power Supply Wiring; Control Power Supply; Water Pump Power Supply; Interlock Wiring - Trane RTAA-70 Installation & Maintenance Manual

Installation — Electrical

Power Supply Wiring

All power supply wiring must be sized and selected accordingly by the project
engineer in accordance with the National Electrical Code.
All wiring must comply with local codes and the National Electrical Code. The
installing (or electrical) contractor must provide and install the system inter-
connecting wiring, as well as the power supply wiring. It must be properly
sized and equipped with the appropriate branch circuit protection. The type
and installation location(s) must comply with all applicable codes.
Cut holes for the appropriately-sized wiring conduits in the lower right side of
the power connection panel. The wiring is passed through these conduits and
connected to the terminal blocks or optional unit-mounted disconnect or
circuit breaker.
To provide proper phasing of 3-phase input, make connections as shown in
the Field Wiring diagrams and as stated on the yellow WARNING label in the
starter panel. For additional information on proper phasing, refer to "Unit
Voltage Phasing" . Proper equipment ground must be provided to each ground
connection in the panel.

Control Power Supply

The unit is equipped with the control power transformer. It is not necessary
to provide control power voltage to the unit.
Heat Tape Power Supply (Packaged Units Only)
NOTE: Units with the Remote Evaporator option do not have heat tape.
The evaporator shell is insulated from ambient air and protected from freezing
temperatures by a thermostatically-controlled heat tape. Whenever the
chilled water temperature drops to approximately 37 F , the thermostat
energizes the heat tape. The heat tape will protect the evaporator from
ambient temperatures down to -20 F
Provide an independent power source (115V, 15 amp), with a fuse disconnect.
The heat tape is factory wired back to the unit control panel. Customer
connections are made on terminal strip 1TB3, terminals 16 and 17 .

Water Pump Power Supply

Provide power supply wiring with fused-disconnect for the chilled water
pump(s) unless unit is equipped with optional pump package.

Interlock Wiring

CAUTION
Evaporator Damage!
The chiller water pump must operate for a minimum of one
minute after the UCM receives a command through the external
Auto/Stop input to shut down the chilled water system. Do not
use the proof of chiller water flow interlock (1U1 TB3-1 and -2) by
itself as the normal means of terminating chiller operation. Failure
to continue pump operation for one minute after unit shut down
may result in evaporator freeze up.
Normally, when the compressors are terminating a cycle (when chiller Stop
key, loss of load, low ambient run inhibit, or external Auto/Stop), the controller
will initiate the "Run: UNLOAD" mode. This operating mode commands the
compressors to their complete unloaded position, which takes about 1/2
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