Operating instructions

TM 11574A-OI
2-47
2-17. Startup
a. Power Connections
.
WARNING
Beware of unannounced starting of the evaporator and condenser fans. The unit may
cycle the fans and compressor unexpectedly as control requirements dictate.
WARNING
Do not attempt to remove power plug(s) before turning OFF start-stop switch (ST), unit
circuit breaker(s) and external power source.
WARNING
Make sure the power plugs are clean and dry before connecting to any power receptacle.
(1) Connection to 380/460 VAC Power
(a) Make sure start-stop switch (ST, on control panel) and circuit breaker (CB-1, in the
control box) are in position “O” (OFF).
(b) Plug the 460 VAC (yellow) cable into a de-energized 380/460 VAC, 3-phase power
source. Energize the power source. Place circuit breaker (CB-1) in position “I” (ON).
Close and secure control box door.
(2) Connection to 190/230 VAC Power. An autotransformer (1, Figure 2-16) is required to allow
operation on nominal 230 volt power. It is fitted with a 230 VAC cable and a receptacle to
accept the standard 460 VAC power plug. The 230 volt cable is black in color while the 460
volt cable is yellow. The transformer may also be equipped with a circuit breaker (CB-2).
The transformer is a step-up transformer that will provide 380/460 VAC, 3-phase, 50/60 hertz
power to the unit when the 230 VAC power cable is connected to a 190/230 VAC, 3-phase
power source.
(a) Make sure that the start-stop switch (ST, on control panel) and circuit breakers CB-1 (in
the control box and CB-2 (on the transformer) are in position “O” (OFF). Plug in and lock
the 460 VAC power plug at the receptacle on the transformer.
(b) Plug the 230 VAC (black) cable into a de-energized 190/230 VAC, 3-phase power
source. Energize the power source. Set circuit breakers CB-1 and CB2 to position “I”
(ON). Close and secure control box door.