9
Figure 4
:
Location Requirements for Suction
Line Filter Installation after Motor
Burnout
The scroll compressors in the RAUP
units do not unload. Instead, they are
staged on and off for various steps of
loading. This sequence is critical
and must not be changed! Altering
this sequence in any way could cause
compressor failure.
Compressor
Motor Winding Ther mostat
Each motor winding thermostat is a
pilot duty control designed to stop
compressor operation if the motor
windings become hot due to rapid
cycling ,loss of charge, abnormally low
s u c t i o n t e m p e r a t u r e s, o r t h e
compressor r unning backwards.
Compressor Manifold Piping
The compressor refrigerant piping
manifold system was purposely designed
to provide proper oil return to both
compressors; therefore, the original
refrigerant manifolding system should
not be modified in any way!
If a compressor replacement is required,
do not alter the compressor manifold
piping; improper oil retur n and
compressor failure could result.
If a suction filter is required, install it a
minimum of 18” upstream of the
compressor manifold piping.
See Figure 4
Caution : Altering the original
manifold piping may cause oil
compressor failure.
This sequence is of most importance
because it maximizes lubrication and
ensure proper oil return. Secondly, the
design of the oil return with equalizer
is critical. The lead compressor must
always be in the lead in the sequence.
Should it fail, it locks out the circuit
i m m e d i a t e l y, s av i n g t h e o t h e r
compressor.
Note: 1, 2, 3 and 4 indicate which compressor in the unit is operat-
ing. (%) indicates the amount of the circuit in the operation during a
given step. Refer to dimensional data for the location of the compressors
1, 2, 3 and 4 in the RAUP unit.
Table 2B
Compressor Sequencing
Unit
Size
250
300
400
500
600
Control
Step
1
2
1
2
3
4
Circuit
Comp.1
1
(50%)
1,2
(100%)
1
(50%)
1,2
(100%)
Circuit
Comp.2
-
-
-
-
3,4
(100%)
Oil Equalizer Line
Compressor 2
Suction Line
(Compressor 1)
Compressor 1
Minimum 18 straight,
unobstructed piping
to suction line filter
Common
Suction Gas
from Evaporator
Oil Seperator Tee
Suction Line
(Compressor 2)
Note: Anytime one compressor is
replaced, the oil charge for the
remaining compressor must be
replaced.
Compressor
1,2
1,2
(100%)
(100%)
-
3 (50%)
