CGAD-SVN02C-EN30
Electrical Phasing of the Scroll
Compressor
It is very important that the right rotation of
the Scroll Compressor is established
before the equipment starts up. The
correct rotation of the motor needs the
confirmation of the sequence of phases
from the supply electrical energy. The
motor is internally connected to turn
clockwise with the phased energy supply
in A, B, and C. In order to confirm the
energy's correct sequence (ABC), use the
phasemeter model 45 or similar one.
Basically the voltage generated at each
phase by a polyphase alternator is called
the phase voltage. In a three-phase circuit,
three voltage solenoids are generated,
dephased by 120 electric degrees. The
order in which the three voltages of the
three-phase system succeed each other
is called the phase sequence or rotation
phase. This is determined by the direction
of the rotation of an alternator. When the
rotation is clockwise, the phase sequence
is called "ABC"; when the direction is
counterclockwise, it is "CBA".
This direction can be changed outside the
alternator by swapping any one of the
cables of the energy supply line. This
possible need of interchanging cables
makes it so that the operator needs to use
the phasemeter in order to quickly
determine the motor's rotation.
Correcting an Improper Phase Sequence
The correct phase sequence of the electric
motor can be quickly determined and
corrected before the unit starts up. Use an
instrument with a quality similar to the
Model 45 phasemeter and carry out the
following procedure:
2.1. Put the unit's RCM switch in the OFF
position.
2.2. Open the circuit's protective
disconnect that supplies energy to the
power terminals.
2.3.Turn on the phasemeter at the outlet of
the disconnect.
2.4.Turn on the electric energy by closing
the disconnect.
2.5 Read the phase sequence shown on
the indicator. The ABC led indicates that the
phase sequence is ABC.
cable P hase Terminal
Black A 1
Red B 2
Yellow C 3
Electrical
Data
Fig. 12 - Phase Sequence Indicator (Phasemeter)
AB C C BA
Black
Red
Yellow
Yellow
Red
Black
Model 45
Phase sequence indicator
90 700V 60 C.P.S.
Amarelo
Vermelho
Preto
Yel l ow
Red
Black
WARNING!!
Take extra care when executing
services with energized equipment
sinc
To prevent accidents or death from electric
shocks, be very careful when executing the
service procedures when the electrical
energy is on.
WARNING!!
2.6.If the LEDs show "CBA", open the
disconnect and switch two phases at the
outlet, close the disconnect, and check the
phasing once again.
2.7. Turn off the unit and disconnect the
phasemeter.
Power Supply
The supply of electrical energy to the unit
should be carefully checked so that the unit
operates normally. The total voltage
supplied and the unbalance between
phases should be within the tolerances
indicated below:
Voltage Supply
The units can come as voltages
of 220 / 380 / 440V, 3P, and 50 or
60 Hz. Measure the supply voltage for all
the phases of the electric disconnects. The
readings should be within the voltage
range of utilization shown on the unit's
plate, which is the nominal voltage +/-
10%. If the voltage of some phase is not
within the tolerance, communicate this to
the power company so that they can
correct the situation before starting up the
equipment. Inadequate voltage in the unit
will cause poor operation in the controls
and will shorten the life of the contacts on
the contactors and electric motors.
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