Influence of voltage fluctuations on thermal loads of induction machine - preliminary investigations

One of power quality disturbances are voltage fluctuations, defined as series of changes of voltage rms value or envelope of voltage waveform. Cyclic voltage fluctuations can be considered as superposition of subharmonics and interharmonics - components of frequency not being an integer multiple of the fundamental one, respectively lower or higher than the fundamental frequency. Supply with voltage containing subharmonics and interharmonics causes flow of additional windings current components that are comparatively weekly suppressed because its low frequency. Even apparently inconsiderable subharmonic content in the supply voltage may lead to windings current subharmonics of significant value. Consequently, voltage fluctuations may lead to considerable increase power losses inside a machine and overheating of windings. The paper deals with preliminary experimental investigations of influence of voltage fluctuations on temperature distribution in a low-power induction cage machine