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The paper outlines failures of selected avionic electric power devices operated onboard of combat helicopters in Iraq and

The paper deals with operational issues related to DC generators of commutator types. Specific aspects of commutation are discussed in details as well as the effect of physical phenomena onto formation of the constant component in the pulsation waveform of the output voltage supplied by DC generators. The component of pulsation is the result of many physical phenomena and, according to knowledge sourced from the related literature, is split into several components. Each of these components is discussed in systematic way on the basis of theoretical background provided by referenced textbooks and papers and then verified by comparison against results of own research studies carried out in the ITWL laboratory. Particular attention is paid to effects associated with the commutation process, with consideration of symptoms related to failures, possibilities of their detection and prevention. Some other effects associated with variation in the nature of pulsation are discussed as well when defects such as shorts or breaks occur in the generator armature or stator. It has been demonstrated that those components of DC generators can be diagnosed by analysis of parameters in pulsation components.

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