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Optimization of the dynamic characteristics of gas filled surge arresters at the low -voltage level.

dc.contributor.advisorOsmokrović, Predrag
dc.contributor.otherCvetić, Jovan
dc.contributor.otherVasić-Milovanović, Aleksandra
dc.contributor.otherVujisić, Miloš
dc.contributor.otherStanković, Koviljka
dc.creatorBrajović, Dragan V.
dc.date.accessioned2016-08-13T10:00:42Z
dc.date.available2016-08-13T10:00:42Z
dc.date.available2020-07-03T08:34:58Z
dc.date.issued2014-04-11
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=3555
dc.identifier.urihttp://nardus.mpn.gov.rs/handle/123456789/6225
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:12281/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=46614543
dc.description.abstractElectrical Engineering / Materials in Electrical Engineering, Nuclear Engineering
dc.description.abstractCilj rada je da se poprave karakteristike gasnih odvodnika prenapona na niskonaponskom nivou istraživanjem kroz eksperimente koji se vrše na modelu gasnog odvodnika prenapona, kao i na komercijalnim gasnim odvodnicima u dobro kontrolisanim laboratorijskim uslovima. U uvodnim poglavljima rada navode se osnove električnog pražnjenja u gasovima, daju osnovne klasifikacije prenapona, propratnih efekata i prenaponske zaštite. Opisuju se gasni odvodnici prenapona i njihovo funkcionisanje koje se zasniva na električnom proboju gasova. Polazeći od poznatih efekata električnog pražnjenja u gasovima, jonskog izbijanja, fotoelektričnog efekta, memorijskog efekta, hladne i tople emisije i efekta jonizujućeg zračenja u gasovima, ispituju se uslovi koji obezbeđuje pouzdan rad gasnih odvodnika prenapona za koordinaciju izolacije na niskonaponskom nivou u uslovima opterećenja impulsnim naponima proizvoljnog oblika. Rad je teoretskog, eksperimentalnog i numeričkog karaktera. U radu se proverava mogućnost primene kinetičke teorije gasova na gas slobodnih elektrona kao komponentu smeše gasa unutar kojeg je nastao usled dejstva sekundarnog kosmičkog zračenja i sudarnih procesa atoma gasa sa desnog kraja Maksvelovog spektra pri niskim pritiscima. Na bazi ove analize izvode se novi izrazi za jonizacione koeficijente izražene preko ekvivalentne probojne temperature Maksvelovog spektra gasa slobodnih elektrona. To omogućava sagledavanje elementarnih procesa pražnjenja u gasovima, a sve u cilju ostvarenja krajnjeg cilja koji se sastoji u tome da se uz zadržavanje svih dobrih osobina gasnih odvodnika prenapona poprave njegove karakteristike. Na osnovu teoretskih razmatranja izvedeni su izrazi zavisnosti probojnog napona od pd (proizvod pritiska i medjuelektrodnog rastojanja) kao i zavisnost probojnog napona od probojne temperature Maksvelovog spektra gasa slobodnih elektrona. Prethodno navedena teoretska razmatranja su eksperimentalno proverena pod dobro kontrolisanim laboratorijskim uslovima. Primenjujući različitu topografiju elektrodnih površina, efekat šuplje katode i radioaktivnog zračenja daje se doprinos konstruktivnom rešenju za brzinu odziva gasnih odvodnika prenapona. U cilju provere pretpostavke o važenju Maksvelove raspodele za gas slobodnih elektrona i primenljivosti izvedenih izraza za Taunzendove(Townsend) koeficijente razvijen je originalni merni postupak pomoću kojeg je moguće merenje jednosmernog i dinamičkog probojnog napona uz uzimanje u obzir memorijskog efekta. Tako razvijen merni postupak se koristi za fino podešavanje impulsnih karakteristika gasnih odvodnika prenapona koje omogućavaju veliku brzinu odziva i stabilnu radnu tačku na duži vremenski period. To je postignuto varijacijom elektrodnih efekata koji utiču na jednosmerni i dinamički proboj gasova i primenom radioaktivnih izotopa. Rezultati dobijeni realnim i numeričkim eksperimentom su pokazali dobro slaganje, kako međusobno, tako i sa teoretski očekivanim rezultatimasr
dc.description.abstractThe purpose of this paper is to improve the characteristics of overvoltage gass arresters on a low-voltage level, through experiments which were done on a model of overvoltage gass arresters in well controlled laboratory conditions. In the first chapters of the paper, the bases of electrical discharge in gasses are given, the basic classification of overvoltage, overvoltage effects and safety issues are given as well. We have described overvoltage gass arresters and their functioning which is based on electrical gass breakage. We have also discussed the known effects of electrical discharge in gasses, ionian outbreak, photoelectric effect, memory effect, cold and warm emissions and effects of Ionic emissions in gasses, and we have examined the conditions which provide reliable operating of overvoltage gass arresters for coordination of isolation on a low-voltage level, in the conditions of a load by impuls voltage, of an arbitary shape. The paper is of a theoretical, experimental and numerical character. It examines a possibility of application of kinetic gass theory onto the gass of free electrones as a component of a gass mixture within which it was created, as a result of the effect of the secondary cosmic emission and collision processes of gass atoms from the right end of the Makswel spectrum, upon low pressure. Based on the results of this analysis, we have given new expressions for Ionic coefficients, expressed by equivalent breakdown temperature of the Makswel spectrum of the gass of the free electrones. That allows insight into elementary processes in gass discharge, in the purpose of reaching the final goal – to improve the characteristcs of gass arresters while keeping their positive traits. Based on theoretical discussions, we have given expressions of dependance on breakdown voltage of pd (product of pressure and inter-electrode distance), as well as the dependance of overvoltage power on breakdown temparature of the Makswel spectrum of the gass of the free electrones. Previously mentioned theoretical discussions are experimentally checked under well controlled laboratory conditions. By applying different topography of electrode surfaces, the effect of hollow cathode and radioactive emission, a significant contribution is given to the constructive solution for the speed of response of gass arresters of the voltage. In order to check the assumptions of the validity of Makswel distribution for the gass of the free elctrones and the application of the expressions for Thousand’s coefficient, we have developed an original measuring method by which it is possible to measure unilateral dynamic breakdown voltage, taking into consideration the memory effect. Such measuring method is used for fine adjustments of impulse charatcteristics of overvoltage gass arresters which allow high speed of response and stable operating point in a longer period. It is achieved by variations of electrode effects which influence unilateral and dynamic gass breakdown and by application of radioactive isotopes. The results which are made by real and numerical experiments have proven good compatibility with themselves as well as with theoretical resultsen
dc.formatapplication/pdf
dc.languagesr
dc.publisherУниверзитет у Београду, Електротехнички факултетsr
dc.rightsopenAccessen
dc.sourceУниверзитет у Београдуsr
dc.subjectdielektriksr
dc.subjectdielectricen
dc.subjectovervoltagesen
dc.subjectgas breakdownen
dc.subjectfree electron gas Maxwell spectrumen
dc.subjectprenaponisr
dc.subjectproboj gasovasr
dc.subjectMaksvelov spektar gasa slobodnih elektronasr
dc.titleOptimizacija dinamičkih karakteristika gasnih odvodnika prenapona na niskonaponskom nivousr
dc.titleOptimization of the dynamic characteristics of gas filled surge arresters at the low -voltage level.en
dc.typedoctoralThesis
dc.rights.licenseARR
dcterms.abstractОсмокровић, Предраг; Цветић, Јован; Васић - Миловановић, Aлександр; Вујисић, Милош; Станковић, Ковиљка; Брајовић, Драган В.; Оптимизација динамичких карактеристика гасних одводника пренапона на нисконапонском нивоу; Оптимизација динамичких карактеристика гасних одводника пренапона на нисконапонском нивоу;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/5452/Disertacija4189.pdf


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