IN SITU REPAIRED HERMETIC COMPRESSORS
Initially, majority of the hermetic compressors are made to allow in-situ repair. Frequently called as bolted hermetic compressors, these might be completely disassembled, repaired and assembled on the line. This is an advantage for big-size compressors where the transportation of the heavy components and compressor proper are not preferred and expensive if handled as a single unit.
On the other hand, in-situ repair operations are not likely for the sealed hermetic compressors or those fabricated as welded constructions and therefore they should be delivered back to their manufacturers or service dealers, irrespective whether it was the drive unit or a small valve that was broken. In such case, the broken compressor should be replaced.
The hermetic compressors with welded construction are available as fraction of a horse power up to the capacities of almost 7.5 tph in general. There are bigger hermetic compressors whose weight as a single unit might be up to 20.0 tons.
In most cases, consideration should be given for replacement of the compressor as a whole. This is in fact the case, which is not always necessarily on technical reasons. During 1950s when the world witnessed a real boom in air conditioning systems, it was also found out that there would not be sufficient technical service team to provide in-situ service to the compressors. It was not recommended for the consumers to make necessary spare parts available for in-situ service, which may have considerable financial impact.
The industry has improved thanks to the mass production and standardization of the compressors. Meanwhile, there have been numerous technical improvements including, but not limited to, the availability of completely pre-charged compressors in their cooling circuit. The rapid development in the system reliability and average service life has enable trouble-free operation without providing service to the compressor and it has become economical to replace the compressors with capacities up to 7.5 tph as a whole rather than providing service. It is most likely that the hermetic compressors with welded construction with a capacity between 1.5 and 5.0 tph will soon dominate in the air conditioner market for great many commercial cooling applications. It is therefore, the technicians will not bother themselves to disassemble the compressors completely for repair. It is therefore better for a technician to focus on the methods to reduce the necessity of the regular service and minimum breakdowns rather than complete repair of compressor.
It is likely for the technicians to have better idea on the compressor technologies who work for operations that make use of big air conditioners that calls for in-situ repairs. At this point, the complete disassembly and assembly of a compressor will turn out to be a creative art rather than a science, where commentary on the manufacturers’ design is crucial.
Almost all motors used in the cooling applications are induction type.
They are named after as such because there is an induction process in the drive of the rotor that has no physical contact with the source of power. The stationary and rotary parts of the motor are called stator and rotor, respectively. The stator windings are fed from the power source. The rotor is installed on the motor shaft and its rotation under induction of the stator windings provides the drive force.
