070.655-IOM (FEB 22)
Page 23
SBTP Rotary Screw Compressor
Maintenance
Troubleshooting guide
Successful problem solving requires an organized approach
to define the problem, identify the cause, and make the
appropriate correction. Sometimes it is possible that two
relatively obvious problems combine to provide a set of
symptoms that can mislead the troubleshooter. Be aware
of this possibility and avoid solving the wrong problem.
Abnormal operation analysis and correction
Four logical steps are required to analyze an operational
problem effectively and make the necessary corrections:
1.
Define the problem and its limits.
2. Identify all possible causes.
3. Test each cause until the source of the problem is
found.
4. Make the necessary corrections.
The first step in effective problem solving is to define the
limits of the problem. The following list of abnormal sys-
tem conditions can cause abnormal operation of the SBTP
compressor:
•
Insufficient or excessive
refrigerant or gas load.
• Excessively high suction pressure.
• Excessively high discharge pressure.
• Excessively high or low temperature coolant to the oil
cooler.
• Excessive liquid entering the compressor (slugging).
•
Insufficient oil cooling.
• Excessive oil cooling.
• Incorrect gas line sizing.
• Incorrect system piping.
• Wrong operation of hydraulic operated slide valve.
• Problems in electrical service to compressor.
• Moisture present in the system.
Make a list of all deviations from normal compressor
operation. Delete any items, which do not relate to the
symptom and separately list those items that might relate
to the symptom. Use the list as a guide to further investi-
gate the problem.
The second step in problem solving is to decide which
items on the list are possible causes and which items are
additional symptoms. High discharge temperature and high
oil temperature readings on a display may both be symp-
toms of a problem and not causally related.
The third step is to identify the most likely cause and take
action to correct the problem. If the symptoms are not
relieved, move on to the next item on the list and repeat
the procedure until you have identified the cause of the
problem. Once the cause has been identified and con
-
firmed make the necessary corrections.
Replacing the capacity linear transmitter: slide
valve
The capacity linear transmitter is located on the end of the
compressor cylinder. See
. The linear transmit-
ter with hermetic enclosure is based on the inductive
measuring principle. It features removable electronics,
from the sensor well, eliminating the need to evacuate the
compressor for replacement. This type of transmitter is
dedicated to capacity control and is not adjustable.
1. Shut off control power.
2. Remove DIN connector plug from transmitter.
3. Loosen cap screws.
4. Remove transmitter unit.
5. Install new transmitter unit.
6. Tighten cap screws.
7. Apply DIN connector plug to transmitter.
8. Turn on control power.
Figure 21: Capacity slide linear transmitter
END VIEW
DIN CONNECTOR
STAINLESS STEEL WELL
HEAT ISOLATOR
CAST ALUMINUM HOUSING
COMPRESSOR UNLOAD CYLINDER
SHADED AREA SHOWS
CAPACITY LINEAR TRANSMITTER
Note:
Shaded are shows capacity linear transmitter.
Replacing the volumizer transmitter: slide stop
The volumizer, or slide stop, transmitter is located on
the right side of the compressor facing the shaft, at the
inlet end. See the following figure:
Figure 22: Volumizer transmitter
DIN connector 43650-A
Printed circuit board
Cast aluminum housing
Stainless steel
sensor well
DIN connector
Heat isolator
End view
Stainless steel well
Compressor unload cylinder
Cast aluminum housing
