The capacity control serves to adapt the compressor capacity at any moment as
closely as possible to the refrigerating capacity. In order to adjust the capacity, a
number of cylinders can be put in or out of action either individually or collectively
by means of solenoid valves.
Warning!
Due to start-up limitations and to limitations of part load operation it
may be that not all available part load steps are allowed under certain
conditions. Use of incorrect control steps can damage compressor
and/or components.
For a detailed description about start-up and part load limitations refer to GEA
Grasso Selection Software.
1.4.9.2 WIRING LOGIC NORMALLY OPEN UNLOADED START SOLENOID
1.
If compessor is NOT running then NO-solenoid is not energised.
2.
Energise the NO-solenoid 10 - 20 seconds before starting.
3.
If compressor starts then NO-solenoid is energised and de-energised by
means of an auxiliary time relay.
4.
Ensure that the NO-solenoid valve is not de-energised until the minimum
allowed compressor speed has been achieved and the specified lubrication oil
pressure has been established.
5.
Energise the NO-solenoid 5 seconds before stopping until the compressor is
stopped completely.
1.4.9.3 Frequency controlled compressor
Hint!
In case of frequency controlled compressors, a separate instruction
00.87.041 is required. If you don’t have this instruction consult Grasso.
1.4.9.4 Pre-start check list
The following Paragraph covers only the initial start of the compressor and not
the complete refrigeration plant.
Be sure that all necessary system valves are open and that the refrigeration
system is ready for start up. Use the following check to guarantee that no items of
importance regarding the compressor (package) have been overlooked.
i.
System is charged with refrigerant.
ii.
Settings of safety limit switches are adjusted properly.
iii.
Direction of rotation of compressor crankshaft is correct.
iv.
Check capacity control: Set the electrical capacity control to the position of the
lowest part load step.
v.
Oil level established in sight glass.
INSTALLATION AND PREPARATION FOR USE
PREPARATIONS FOR USE
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