Industrial Climate Engineering ECUA90 Installation & Operation Manual page 17

that the suction pressure drops and the discharge pressure rises when the compressor is energized. An
alternate method of verification for self contained system with small critical refrigerant charges, where
the installation of gauges may be objectionable, can be made by monitoring the temperature of the
refrigerant lines at the compressor. The temperature should rise on the discharge line while the suction
line temperature decreases. Reverse rotation also results in a substantially reduced current draw when
compared to tabulated values.
There is no negative impact on durability caused by operating three phase compressors in the reversed
direction for a short duration of time, usually defined as less than one hour. However, after several
minutes of operation the compressor's internal protector will trip. The compressor will then cycle on
the protector until the phasing is corrected. Reverse operation for longer than one hour may have a
negative impact on the bearings.
To change the rotation, turn off power to the unit and reverse L1 & L2 at the disconnect in the air
conditioner.
High Voltage Wiring - (Single Units)
The power supply should have the proper voltage, phase, and ampacity for the selected model.
1. Refer to the electrical data on the data sticker on the unit for field wiring requirements of the unit.
Size the incoming power supply lines and the fuse(s) or HACR breaker(s) according to requirements
described in the National Electric Code. Run the power conductors through the knockouts on the
side or back of the unit. Use appropriate conduit and strain reliefs.
Note: Power supply service must be within allowable range (+10% - 5%) of rated voltage
stamped on the unit rating plate. To operate nominal 230/208V unit at 208V, change the
transformer line tap from 240V to 208V following the instruction on wiring label in unit.
2. Connect the wires to the input side of the internal breaker or terminal block (L1 & L2 for single-
phase units; L1, L2, & L3 for three-phase models).
3. Install the ground wire on the ground lug.
4. For units designed for operation on 208/230V, 60Hz power supply, the transformer is factory wired
for a 230V power supply. For a 208V power supply, remove the orange lead from the transformer
and connect the red lead. Insulate the orange lead.
The external breaker(s) that provide power to the air conditioner must be sized per the
maximum Fuse Size (MFS) shown on the Unit's data label.
Dual Unit Phasing
For applications where one controller operates two units, e.g., the CommStat 4.
1. Wire each unit as described in steps 1 through 4 above.
2. Test for proper phasing as follows:
A. Power up the units.
B. Using an AC volt meter set to the 300 volt scale, measure voltage between terminal L1 on the
compressor contactor of unit #1 and terminal L1 on the compressor contactor of unit #2 If
voltage is present, units are wired out of phase and must be rewired.
C. If units are not in phase, turn off power and reverse the field power leads connected to the
internal circuit breaker on one of the units only.
D. Restore power and retest the phase (step B). When the voltage reads "0", the units are in phase.
E. Turn off power and proceed.
CAUTION
CAUTION
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ECU 12/2014 NEW