Evaluation of the degradation of generator stator ground wall insulation under multistresses aging / Zhidong, Jia in IEEE transactions on energy conversion, Vol. 23 n°2 (Juin 2008)  

Public ISBD [article]  inIEEE transactions on energy conversion > Vol. 23 n°2 (Juin 2008) . - pp. 474 - 483 Titre : Evaluation of the degradation of generator stator ground wall insulation under multistresses aging Type de document : texte imprimé Auteurs : Zhidong, Jia, Auteur ; Xiang, Peng, Auteur ; Zhicheng, Guan, Auteur Année de publication : 2008 Article en page(s) : pp. 474 - 483 Note générale : Energy conversion Langues : Anglais (eng) Mots-clés : Weibull distribution  ageing  electric breakdown  generators  machine insulation Résumé : The actual stator bars of an 18 kV/300 MW generator were used for accelerated multistress aging tests to investigate the degradation of ground insulation. An aging system with combined stresses including thermal, electrical, mechanical vibration, and thermomechanical factors was used to test the aging of stator bar specimens. The nondestructive parameters including partial discharge (PD) quantities and dissipation factor parameters were measured during aging test in order to evaluate the degradation of stator ground wall insulation. At the end of the aging test, an AC breakdown test was performed on the bars in order to obtain the remaining breakdown voltage (BDV) after their nondestructive data had been measured. The changes of nondestructive parameters indicated that the degradation of ground wall insulation. For example, the changes of skewness of indicated the shape of voids in ground insulation changes from flat to narrow, and even exhibits treeing, which is dangerous to insulation because it shortens the effective distance of insulation between high voltage and the ground. The results obtained are summarized as follows. The BDV data fit a Weibull distribution. The correlation between the dissipation factor, the PD parameters, and the breakdown voltage were analyzed, among which the skewness of the average discharge had the most correlation with breakdown voltage. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4505392&sortType%3Das [...] [article] Evaluation of the degradation of generator stator ground wall insulation under multistresses aging [texte imprimé] / Zhidong, Jia, Auteur ; Xiang, Peng, Auteur ; Zhicheng, Guan, Auteur . - 2008 . - pp. 474 - 483. Energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 23 n°2 (Juin 2008) . - pp. 474 - 483 Mots-clés : Weibull distribution  ageing  electric breakdown  generators  machine insulation Résumé : The actual stator bars of an 18 kV/300 MW generator were used for accelerated multistress aging tests to investigate the degradation of ground insulation. An aging system with combined stresses including thermal, electrical, mechanical vibration, and thermomechanical factors was used to test the aging of stator bar specimens. The nondestructive parameters including partial discharge (PD) quantities and dissipation factor parameters were measured during aging test in order to evaluate the degradation of stator ground wall insulation. At the end of the aging test, an AC breakdown test was performed on the bars in order to obtain the remaining breakdown voltage (BDV) after their nondestructive data had been measured. The changes of nondestructive parameters indicated that the degradation of ground wall insulation. For example, the changes of skewness of indicated the shape of voids in ground insulation changes from flat to narrow, and even exhibits treeing, which is dangerous to insulation because it shortens the effective distance of insulation between high voltage and the ground. The results obtained are summarized as follows. The BDV data fit a Weibull distribution. The correlation between the dissipation factor, the PD parameters, and the breakdown voltage were analyzed, among which the skewness of the average discharge had the most correlation with breakdown voltage. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4505392&sortType%3Das [...]

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Laboratory studies of a new stator slot wedge tester for HV generators / Xiang, Peng in IEEE transactions on energy conversion, Vol. 24 N°1 (Mars 2009)  

Public ISBD [article]  inIEEE transactions on energy conversion > Vol. 24 N°1 (Mars 2009) . - pp. 146 - 152 Titre : Laboratory studies of a new stator slot wedge tester for HV generators Type de document : texte imprimé Auteurs : Xiang, Peng, Auteur ; Zhidong, Jia, Auteur ; Shengqiang, Gao, Auteur Année de publication : 2009 Article en page(s) : pp. 146 - 152 Note générale : energy conversion Langues : Anglais (eng) Mots-clés : Digital signal processing chips  electric generators  machine analysis computing  hardware-software codesign  testing  windings Résumé : Stator winding vibration is the most common cause of unexpected failure of high-voltage (HV) generators. Stator bars are generally fixed in slots by using slot wedges and a side packing system. Loose slot wedges could result in excessive vibration of the stator bars, which would accelerate the deterioration of the ground wall insulation. Loose slot wedge testing is consequently one of the most important general examination procedures to make sure the condition of HV generators. The common method used for slot wedge testing is manual measurement, whereby the slot wedge is tapped by hand using a small hammer. A judgment on looseness is made based on the sound from it. A digital signal processor (DSP)-based loose slot wedge tester is described in detail in this paper, including both hardware and software design. It was developed in our laboratory based on the study of slot wedge vibration characteristics in its loosening process. Since embedded software system of the DSP is oriented to a specific industrial field while PC system is of a general purpose, the device has many advantages compared to traditional manual measurement or other slot wedge testing equipment, such as portability, high intelligence, low power consumption, etc. The tester was applied for laboratory loose slot wedge testing of a slot model. The test results soundly verified the good performance of the device. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4749290&sortType%3Das [...] [article] Laboratory studies of a new stator slot wedge tester for HV generators [texte imprimé] / Xiang, Peng, Auteur ; Zhidong, Jia, Auteur ; Shengqiang, Gao, Auteur . - 2009 . - pp. 146 - 152. energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 24 N°1 (Mars 2009) . - pp. 146 - 152 Mots-clés : Digital signal processing chips  electric generators  machine analysis computing  hardware-software codesign  testing  windings Résumé : Stator winding vibration is the most common cause of unexpected failure of high-voltage (HV) generators. Stator bars are generally fixed in slots by using slot wedges and a side packing system. Loose slot wedges could result in excessive vibration of the stator bars, which would accelerate the deterioration of the ground wall insulation. Loose slot wedge testing is consequently one of the most important general examination procedures to make sure the condition of HV generators. The common method used for slot wedge testing is manual measurement, whereby the slot wedge is tapped by hand using a small hammer. A judgment on looseness is made based on the sound from it. A digital signal processor (DSP)-based loose slot wedge tester is described in detail in this paper, including both hardware and software design. It was developed in our laboratory based on the study of slot wedge vibration characteristics in its loosening process. Since embedded software system of the DSP is oriented to a specific industrial field while PC system is of a general purpose, the device has many advantages compared to traditional manual measurement or other slot wedge testing equipment, such as portability, high intelligence, low power consumption, etc. The tester was applied for laboratory loose slot wedge testing of a slot model. The test results soundly verified the good performance of the device. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4749290&sortType%3Das [...]

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