42
Ensure that the oil sump heaters have been operating for a minimum of 12 hours before first startup
after long time shutdown. Failure to do so may result in compressor damage.
14. Check the oil level of oil separator sump if desired.
Note:
Never to operate the compressor during oil level check.
NOTICE - Compressor Damage!
Check the compressor discharge superheat of each loop through TD7 display. The compressor
discharge superheat should be larger than 1 °C after 12 hours preheat of compressor and oil
separator sump
.
Unit Voltage Power Supply
WARNING - Live Electrical Components!
During installation, testing, servicing and troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified licensed electrician or other individual who has
been properly trained in handling live electrical components perform these tasks.
Failure to follow all electrical safety precautions when exposed to live electrical components could
result in death or serious injury.
Unit voltage must meet the criteria given in the installation Electrical Section. Measure each lead of the
supply voltage at the main power fused-disconnect switch for the unit. If the measured voltage on any lead is
not within the specified range, notify the supplier of the power and correct the situation before operating the
unit.
CAUTION - Equipment Damage!
Inadequate voltage to the unit may cause control components to malfunction and shorten the life of
relay contact, compressor motors and contactors
.
Unit Voltage Imbalance
Excessive voltage imbalance between the phases of a three-phase system can cause motors to overheat
and eventually fail. The maximum allowable imbalance is 2 percent. Voltage imbalance is determined using
the
following calculations:
(V
x
- V
ave
)
x 100
%Imbalance =
= (V
x
+
V
2
+
V
3
)
"
ave
3
Vx = phase with greatest difference from
V
ave
(without regard to sign)
For example, if the three measured voltages are 375, 389, and 388 volts, the average would be:
375 + 389 + 388
V
ave
= ---------- 3 ----------- = 384
V
The percentage of imbalance is then:
(375 - 384) x 100
--------- 384 --------- = 2'
34
%
This exceeds the maximum allowable (2%) by 0.34 percent.
Unit Voltage Phasing
It is important that proper rotation of the compressors be established before the unit is started. Proper motor
rotation requires confirmation of the electrical phase sequence of the power supply. The motor is internally
connected for clockwise rotation (when looking from the end of the motor) with the incoming power supply
phases A-B-C. Catastrophic rotor and housing wear will occur if the compressor is driven in the reverse
^
ave
