Possible small refrigerant leakage through the shaft gland may be acceptable with a great system, but will lead to early fault small circuit. The widespread use of small cooling system led to the evolution of methods of avoiding condensation of a shaft, provided that the working fluids compatible with the materials electric motors and has a high dielectric strength.
In semi-hermetic or get-hermetic compressor (Fig. 4.11) rotor his drive motor integral with extended crankshaft, and the stator is installed inside the extension of the crankcase. Suction gas passing through the engine itself to remove waste heat from the engine. Asynchronous motors can be used with any source switches out of the crankcase, because any sparking will lead to the decomposition of the refrigerant. Electrical wires pass through a ceramic or glass seals. Small compressors will be fully airtight, that is, having the engine and all working parts are sealed inside a steel casing and are not available for repair or maintenance.
The application of the complete hermetic compressor limited to the amount of cooling the incoming cold gas, heat loss from the body, and the potential provision by the oil cooler.
The refusal of the embedded engine will lead to the decomposition products and serious pollution of the system, which then must be thoroughly cleaned. Internal and external motor protection devices are installed with the object of turning off the power before such damage occurs...