The paper discusses typical grounding practices and ground fault protection methods for medium voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to ...applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. Part IV of this paper provides a conclusion and bibliography of additional resource material.
The paper discusses typical grounding practices and ground fault protection methods for medium voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to ...applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. Part III of this paper describes protection methods for the various types of grounding.
The paper discusses typical grounding practices and ground fault protection methods for medium voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to ...applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each method of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. Part II of the paper discusses various grounding methods used in industrial applications.
The paper discusses typical grounding practices and ground fault protection methods for medium voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to ...applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate papers. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem.
A general strategy for the synthesis of phospholipids was developed. The method was demonstrated using 3-O-allyl-sn-glycerol 33 which was regiospecifically converted to ...1-palmitoyl-2-(5-O-TBDMS-stearoyl)-3-O-allyl-sn-glycerol 43 by the sequential acylation of the primary and secondary hydroxyls. The allyl group was removed in two steps by isomerization to a vinyl ether and hydrolysis with N-bromosuccinimide in aqueous tetrahydrofuran. A new method for the conversion of the 1,2-diacylglycerols to phosphatidylcholines under acid-catalyzed conditions was developed. The diacylglycerols were treated with (2-bromoethyl)-($ 2$-cyanoethyl)-(N,N-diisopropylamino)-phosphoramidite 51 in the presence of tetrazole as catalyst, the phosphite triester was oxidized, and the neutral phosphate triester was treated with trimethylamine to simultaneously deprotect the phosphate and convert the bromoethyl substituent to the choline function. A modification was introduced to extend the synthetic strategy to unsaturated phosphatidylcholines. The starting material was 3-(4-methoxybenzyl)-sn-glycerol 30 (3-PMB-sn-glycerol). Diacylation of the hydroxyls with 13-tetradecynoic acid 64a followed by Glaser oxidation gave 1,2-(13,15-octacosadiyn-1-28-dioyl)-3-PMB-sn-glycerol 66. The 4-methoxybenzyl ether was cleaved using bromodimethylborane at $-$78$ sp circ$C in methylene chloride. The diacylglycerol 67 was converted to the phosphatidylcholine as before. Sequential acylation of 30 with palmitic acid and 15-hexadecynoic acid 64b followed by Glaser oxidation gave 2,2$ sp prime$-(15,17-dotriacontadiyn-1,32-dioyl)-bis- (1-palmitoyl-3-PMB-sn-glycerol) 72, which was converted to the bis-phosphatidylcholine 75 in the same manner as 66.
La présence de fibres d'amiante a été recherchée dans des échantillons de vins, de spiritueux et d'eaux-de-vie ayant subi ou non une filtration sur filtre d'amiante. Les produits sont filtrés sur une ...membrane à micropores qui est ensuite traitée en vue de l'examen au microscope électronique. Les fibres sont identifiées par leur morphologie et par leur diagramme de diffraction d'électrons, complétés éventuellement par la microanalyse élémentaire ponctuelle (Edax). L'examen met en évidence la présence de fibres de chrysotile le plus souvent isolées, parfois en agrégats, dans la totalité des boissons filtrées sur amiante, alors que les boissons non filtrées n'en contiennent qu'une faible concentration, voisine de celle de l'eau analysée par ailleurs. Seuls sont rigoureusement exempts de fibres d'amiante deux échantillons de vins de liqueur brut ou filtré sur filtre ne contenant pas d'amiante. Par ailleurs, l'utilisation d'un filtre mixte amiante-cellulose ne donne lieu qu'à une contamination réduite par ces fibres minérales. The presence of asbestos fibres was searched for in samples of wines, brandies and spirits which had or had not been filtered through asbestos filters. The materials examined were filtered on a micropore membrane that was then handled for electron microscope examination. Asbestos fibres were identified by their morphology and X-ray diffraction pattern and in certain cases additionnally by punctual ultimate analysis (Edax). The presence of chrysotile fibres, generally separate but sometimes in clumps, was found in all the drinks which had been filtered through asbestos filters, while the non filtered drinks contained only a small concentration that was approximately equal to the one found in water analysed elsewhere. Only two samples of liquor, raw or filtered through a filter not containing asbestos, were absolutely free from fibres. On the other hand, the use of mixed filters of asbestos and cellulose resulted in only contamination by such mineral fibres.
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