Indirect measurement of hermetic compressor speed through externally-measurable quantities

Compressor speed is a very important parameter when testing hermetic compressors. Its measurement is routine in the refrigerator compressor industry, either to evaluate parameters such as capacity, power consumption, and coefficient of performance (COP), or as an indicator of steady-state operation. However, there are some difficulties associated with measuring the speed of hermetic compressors, mainly concerning uncertainty and time constraints. This study presents some hermetic compressor speed measurement techniques, based on quantities that can be measured outside a compressor shell. In this study it was possible to measure compressor speeds through these techniques with an uncertainty of less than 1 rpm in a measurement time of 5 s.