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(Figures 12 & 13, pages 14 & 15)) for identifi cation and
location of unit fi eld wiring interfaces. Make all electrical
connections in accordance with all applicable codes
and ordinances.
• Overcurrent protection must be provided at the branch
circuit distribution panel and sized as shown on the unit
rating label and according to applicable local codes.
See the unit rating plate for minimum circuit ampacity
and maximum overcurrent protection limits.
• Use only copper wire for the line voltage power supply
to this unit. Use proper code agency listed conduit and
a conduit connector for connecting the supply wires to
the unit. Use of rain tight conduit is recommended.
• 208/230 Volt units are shipped from the factory wired
for 230 volt operation. For 208V operation, remove the
lead from the transformer terminal marked 240V and
connect it to the terminal marked 208V.
• Optional equipment requiring connection to the power
or control circuits must be wired in strict accordance of
all applicable local codes, and the instructions provided
with the equipment.
Overcurrent Protection
Generally, the best fuse or breaker for any air conditioner
is the smallest size that will permit the equipment to run
under normal usage and provide maximum equipment
protection. Properly sized fuses and breakers also prevent
nuisance trips during unit startup. If a fuse blows or a
breaker trips, always determine the reason. Do not
arbitrarily install a larger fuse or breaker and do not,
in any case, exceed the maximum size listed on the
data label of the unit.
Grounding
WARNING:
The unit cabinet must have an uninterrupted or
unbroken electrical ground to minimize personal
injury if an electrical fault should occur. Do not
use gas piping as an electrical ground!
This unit must be electrically grounded in accordance
with local codes or, in the absence of local codes, with
the national codes. Ground the air conditioning unit using
the green grounding screw provided in the control panel.
Unbalanced 3-Phase Supply Voltage
Voltage unbalance occurs when the voltages of all phases
of a 3-phase power supply are no longer equal. This
unbalance reduces motor effi ciency and performance.
Some underlying causes of voltage unbalance may include:
Lack of symmetry in transmission lines, large single-phase
loads, and unbalanced or overloaded transformers. A
motor should never be operated when a phase imbalance
in supply is greater than 2%.
Perform the following steps to determine the percentage
of voltage imbalance:
1. M e a s u r e t h e l i n e
voltages of your 3 phase
power supply where it
enters the building and
at a location that will
only be dedicated to
the unit installation
(at the units circuit
protection or disconnect).
2. Determine the average voltage in the power supply.
In this example, the measured line voltages were
226, 230, and 227. The average would be 228 volts
(226 + 230 + 227 = 683 / 3 = 228).
3. Determine the maximum deviation:
From the values given in step 1, the BC voltage
(230V) is the greatest difference in value from
the average:
230 - 228 = 2
228 - 226 = 2
228 - 227 = 1
4. Determine percent of
voltage imbalance by using
the results from steps 2 &
3 in the following equation.
% Voltage Imbalance
= 100 x
The amount of phase imbalance (0.88%) is satisfactory
since the amount is lower than the maximum allowable
2%. Please contact your local electric utility company if
your voltage imbalance is more than 2%.
Example
:
AB = 226V
BC = 230V
AC = 227V
Example:
Highest Value
Example:
2
100 x
= 0.88%
228
max voltage deviation
from average voltage
average voltage
9
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