Unit Startup
RT-SVX24J-EN
109
internally connected for clockwise rotation with the
incoming power supply phased as A, B, C.
Proper electrical supply phasing can be quickly
determined and corrected before starting the unit by using
an instrument such as an Associated Research Model 45
Phase Sequence Indicator and following the steps below:
•
[ ] Turn the field supplied disconnect switch that
provides power to terminal block or to the unit
mounted disconnect switch to the “Off” position.
•
[ ] Connect the phase sequence indicator leads to the
terminal block or unit mounted disconnect switch as
follows:
•
[ ] Close the disconnect switch or circuit protector
switch that provides the supply power to the unit
terminal block or the unit mounted disconnect switch.
HIGH VOLTAGE IS PRESENT AT TERMINAL BLOCK OR
UNIT DISCONNECT SWITCH.
•
[ ] Observe the ABC and CBA phase indicator lights on
the face of the sequencer.The ABC indicator light will
glow if the phase is ABC. If the CBA indicator light
glows, open the disconnect switch or circuit protection
switch and reverse any two power wires.
•
[ ] Restore the main electrical power and recheck the
phasing. If the phasing is correct, open the disconnect
switch or circuit protection switch and remove the
phase sequence indicator.
Voltage Supply and Voltage Imbalance
Voltage Supply
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.
Voltage Imbalance
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;
AV (Average Voltage) =
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.
Phase Sequence Leads
Unit Power Terminal
Black (phase A)
L1
Red (phase B)
L2
Yellow (phase C)
L3
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.
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.
100
x
AV VD
–
AV
-----------------
Volt1
Volt2
Volt3
+
+
3
-------------------------------------------------
211
230
227
+
+
3
------------------------------------
226 Avg
=
100
x
226 221
–
226
---------------------
2.2 percent
=
