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32 Packaged Heat Pump • WC-IOM-7
Installation
• Check the supply fan belts for proper tension and the fan bearings for
sufficient lubrication. If the belts require adjustment, or if the bearings need
lubricating, refer to the maintenance section of this manual for instructions.
• Verify that a condensate trap is installed and the piping is properly sized and
pitched.
• Verify that the correct size and number of filters are in place.
• Inspect the interior of the unit for tools and debris and install all panels in
preparation for starting the unit.
Voltage Imbalance
Three phase electrical power to the unit must meet stringent requirements for
the unit to operate properly. Measure each leg (phase-to-phase) of the power
supply. Each reading must fall within the utilization range stamped on the unit
nameplate. If any of the readings do not fall within the proper tolerances, notify
the power company to correct this situation before operating the unit.
Excessive three phase voltage imbalance between phases will cause motors to
overheat and eventually fail. The maximum allowable voltage imbalance is 2%.
Measure and record the voltage between phases 1, 2, and 3 and calculate the
amount of imbalance as follows:
% Voltage Imbalance =
where Average Voltage (AV);
V1, V2, V3 = Line Voltage Readings
VD = Line Voltage reading that deviates the farthest from the average voltage.
Example: If the voltage readings of the supply power measured 221, 230, and 227,
the average volts would be:
VD (reading farthest from average) = 221
The percentage of Imbalance equals:
The 2.2% imbalance in this example exceeds the maximum allowable imbalance
of 2.0%. This much imbalance between phases can equal as much as a 20%
current imbalance with a resulting increase in motor winding temperatures that
will decrease motor life. If the voltage imbalance is over 2%, notify the proper
agencies to correct the voltage problem before operating this equipment.
100
AV VD–
AV
-----------------------
⎝⎠
⎛⎞
AV
Volt1 Volt2 Volt3++
3
---------------------------------------------------------------- -
⎝⎠
⎛⎞
=
221 230 227++
3
---------------------------------------------- - 2.2percent=
100
226 221–
226
----------------------------
⎝⎠
⎛⎞
2.2percent=