C6.2.7/0302-0903/E 9
19 Three Phase Models
Scroll Models compressors, like several other types of compressors, will
only compress in one rotational direction. Direction of rotation is not an
issue with single-phase compressors since they will always start and run
in the proper direction. However, three- phase compressors will rotate in
either direction depending upon phasing of the power to L1, L2 and L3.
Since there is a 50/50 chance of connecting power in such a way as to
cause rotation in the reverse direction, it is important to include notices
and instructions in appropriate locations on the equipment to ensure
proper rotation direction is achieved when the sys-tem is in-stalled and
operated. Recommended wiring diagrams are shown in fig. 4.
Figure 4: Power Circuit three phase compressor
Verification of proper rotation direction is made by observing that suction pressure drops and discharge pressure rises
when the compressor starts. Reverse rotation results in a sound level above that with correct rotation direction, as
well as substantially reduced current draw compared to tabulated values and after several minutes of operation the
compressor’s internal protector will trip.
All three-phase compressors are wired identically internally. As a result, once the correct phasing is determined for a
specific system or installation, connecting properly phased power leads to the same terminals should maintain proper
rotation direction.
20 Cable Connectors
Figure 5: Cable Connectors
The above table lists recommended types of cable connectors to be used for the various electric terminals of the
compressors. “A” must fit 1/4" or 6.3 mm tab sizes. “C” are to be selected for #10 studs or diameters of 5mm
respectively. Cable sizes are to be selected according to DIN ISO 0100, IEC 364 or national regulations.
21 Compressor Functional Check
No scroll compressor should be started with the suction service valve closed to check how low the compressor will
pull suction pressure. This type of test may actually damage a refrigeration Scroll compressor, rather, the following
diagnostic procedure should be used to evaluate whether the Scroll compressor is functioning properly.
Proper voltage to the unit should be verified.
Normal motor winding continuity and short to ground checks will determine if the inherent overload motor
protector has opened or if an internal short to ground has developed. If the protector has opened, the compressor
must cool sufficiently to reset.
Model TFD TF5
All Horizontal refrigeration
scroll models
B/C B/C
C SpadeB Ring Tongue
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