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specific electrical schematic is shipped with the unit. Measure each leg of the main power supply voltage at the main
power source. Voltage must be within the voltage utilization range given in Table 1.
Table 1 - Voltage Utilization Range
Rated Voltage
Utilization Range
230
208 to 254
460
414 to 506
575
516 to 633
If the measured voltage on any leg is not within the specified range, notify the supplier and correct before operating the
unit. Voltage imbalance for three-phase systems must not exceed two percent. Excessive voltage imbalance between the
phases of a three-phase system can cause motors to overheat and eventually fail. Voltage imbalance is determined using
the following calculations:
% Imbalance = (V
avg
– V
x
) x 100 / V
avg
V
avg
= (V
1
+ V
2
+ V
3
) / 3
V
x
= phase with greatest difference from V
avg
For example, if the three measured voltages were 442, 460, and 454 volts, the average would be:
(442 + 460 + 454) / 3 = 452
The percentage of imbalance is then:
(452 – 442) x 100 / 452 = 2.2 %
This exceeds the maximum allowable of 2%.
A terminal block is provided for main power connection to the main power source. The main power source should be
connected to the terminal block through an appropriate disconnect switch. A separate lug for grounding the unit is also
provided in the main control panel. Electrical phase sequence must be checked at installation and prior to start-up for all
three-phase systems. Operation of the compressor with incorrect electrical phase sequencing will result in mechanical
damage to the compressors. The phasing must be checked with a phase sequence meter prior to applying power. The
proper sequence should read “ABC” on the meter. If the meter reads “CBA”, open the main power disconnect and switch
two line leads on the line power terminal blocks (or the unit mounted disconnect). All components requiring electric power
are wired in-phase at the factory. Do not interchange any load leads that are from the unit contactors or the motor
terminals.
WARNING: It is imperative that L1-L2-L3 are connected in the A-B-C phase sequence to prevent equipment damage due to reverse
rotation.
CAUTION: The unit requires the main power to remain connected during off-hours to energize the compressor’s crankcase heater if
equipped. Disconnect main power only when servicing the chiller. The crankcase heater should remain on when the compressor is off
to ensure liquid refrigerant does not accumulate in the compressor crankcase.
WARNING: The control panel and safeties are wired such that connecting the appropriate power source to the main terminal block
energizes the entire electric circuitry of the chiller. A control transformer has been factory wired to step down the incoming power to
the 115-volt control power. Electric power at the main disconnect should be shut off before opening access panels for repair or
maintenance. The unit must be properly grounded in compliance with local and national codes.
