48
Figure 29 - Front View of Utility Entry and
Power Switch from Control Compartment
(55, 65 and 75-140 ton Units)
Size supply conductors based on the unit
MCA rating. Supply conductors must be
rated a minimum of 75°C.
Protect the branch circuit in accordance with
code requirements. The unit must be
electrically grounded in accordance with
local codes, or in the absence of local codes,
the current National Electric Code,
ANSI/NFPA 70 or the current Canadian
Electrical Code CSA C22.1.
Note: All units are factory wired for 208V,
230V, 380V, 460V, or 575V. The
transformer configuration must be checked
by a qualified technician prior to service,
especially if unit is to be connected to a
208V or 230V supply. For 208V service
interchange the yellow and red conductor on
the low voltage control transformer.
Red-Black for 208V
Yellow-Black for 230V
Wire power leads to the unit’s terminal
block or main disconnect. All wiring beyond
this point has been completed by the
manufacturer and cannot be modified
without effecting the unit’s agency/safety
certification.
Supply voltage must be within the min/max
range shown on the unit nameplate.
Available short circuit current should not
exceed the short circuit current rating
(SCCR) shown on the unit nameplate.
Three phase voltage imbalance will cause
motor overheating and premature failure.
The maximum allowable imbalance is 2.0%.
Voltage imbalance is defined as 100 times
the maximum deviation from the average
voltage divided by the average voltage.
Example:
(221V+230V+227V)/3 = 226V, then
100*(226V-221V)/226V = 2.2%, which
exceeds the allowable imbalance.
Check voltage imbalance at the unit
disconnect switch and at the compressor
terminal. Contact your local power company
for line voltage corrections.
Installing contractor must check for proper
motor rotation and check blower motor
amperage listed on the motor nameplate is
not exceeded. Motor overload protection
may be a function of the variable frequency
drive and must not be bypassed.
Three phase voltage imbalance will
cause motor overheating and
premature failure.
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