9
Installation - Electrical
All wiring must comply with local codes and the
National Electric Code. Minimum circuit amps (MCA)
and other unit electrical data are on the unit
nameplate. A unit specific electrical schematic ships
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 on
the drawings included with the unit. If the measured
voltage on any leg is not within the specified range,
notify the supplier and correct before operating the
unit. Voltage imbalance 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 = (Vavg – Vx) x 100 / Vavg
Vavg = (V1 + V2 + V3) / 3
Vx = phase with greatest difference from Vavg
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%.
There is a terminal block 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. There is a separate
lug in the main control panel for grounding the unit.
Check the electrical phase sequence at installation
and prior to start-up. Operation of the compressor
with incorrect electrical phase sequencing will result
in mechanical damage to the compressors. Check
the phasing 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). Do not interchange any load
leads that are from the unit contactors or the motor
terminals.
WARNING: This equipment contains hazardous
voltages that can cause severe injury or death.
WARNING: This equipment contains refrigerant
under pressure. Accidental release of refrigerant
under pressure can cause personal injury and or
property damage.
WARNING: This equipment may contain fan
blades or other sharp edges. Make sure all fan
guards and other protective shields are securely
in place.
WARNING: The exposed surfaces of motors,
refrigerant piping, and other fluid circuit
components can be very hot and can cause burns
if touched with unprotected hands.
CAUTION: Disconnect and lock out incoming
power before installing, servicing, or
maintaining the equipment. Connecting power to
the main terminal block energizes the entire
electric circuitry of the unit. Electric power at the
main disconnect should be shut off before
opening access panels for repair or maintenance.
CAUTION: Wear eye protection when installing,
maintaining, or repairing the equipment to
protect against any sparks, debris, or fluid leaks.
CAUTION: Wear protective gloves when
installing, maintaining, or repairing the
equipment to protect against any sparks, debris,
or fluid leaks.
CAUTION: Wire the unit ground in compliance
with local and national codes.
CAUTION: The unit requires the main power to
remain connected during off-hours to energize
the compressor’s crankcase heater. 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. Connect main power at least 24 hours
prior to initial start-up.
