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Output Voltage Pulsation as Source of Diagnostic Information About Commutator-Type DC Generators

Gębura A., Radoń T.

Prace Naukowe Instytutu Technicznego Wojsk Lotniczych

2013

nr 33

75--93

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.

The FDM-A AND FAM-C methods with regard to effects associated with transmission of rf signals

Gębura A., Mroszkiewicz K.

Prace Naukowe Instytutu Technicznego Wojsk Lotniczych

2010

nr 27

151-164

The paper deals with issues related to analogies between methods used for conditioning, transmission and reception of diagnostic signals with use of the FAM-C1 and FDM-A2 techniques and corresponding phases that happen to phenomena associated with transmission of information in radio engineering. All these cases include modulation, transmission and demodulation of FM signals. The only difference is the content of information transmitted: for the diagnostic signal with use of FAM-C and FDM-A techniques it is the information about technical condition of kinematic pairs within the driving unit (demonstrated by defined modulation to angular velocity of kinematic pairs) whilst broadcast signals are used to transmit speech, music or specific sequences of sounds (acoustic signals). The transmission medium is also different. In case of RF signals conveyed between the transmitter and the receiver it can be air, vacuum or water whilst transmission with use of FAM-C and FDM-A techniques assumes signal propagation via rigid tension members of the transmission unit deployed between the monitored kinematic pairs and the electric current generator. The difference lies also in ranges of the carrier frequency - for broadcast transmission with FM modulation the carrier frequency is from a dozen of MHz to hundreds of MHz whilst FAM-C and FDM-A techniques assume the frequency from dozens of Hz to several kHz. The last major difference is also in the heterodyne3 frequency, which is from a dozen of MHz to hundreds of MHz for the RF transmission and from several hundreds of Hz up to several kHz for diagnostic purposes (depending on how the electric machine is designed).