Utjecaj aluminijskih dijelova na pojavu vodika u mjernom transformatoru

scientific master's theses

• Title (english): The influence of aluminum parts to the emergence of hydrogen in instrument transformer
• Author: Željko Tarandek; VIAF: 305776607
• Mentor: Ivan Juraga (mentor)
• Committee member: Zdravko Schauperl (predsjednik povjerenstva)
• Committee member: Ivan Juraga (član povjerenstva)
• Committee member: Davor Pavlić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2011-05-27, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering
• Universal decimal classification (UDC): 669 - Metallurgy ; 621 - Mechanical engineering. Nuclear technology. Machinery

Abstract

Konkurentnost na tržištu uvjetovana je brojnim zahtjevima, od kojih je jedan i kvaliteta proizvoda. Udio otopljenih plinova u transformatorskom ulju jedan je od pokazatelja kojim se može ocijeniti karakteristika mjernog transformatora važna za procjenu njegovog radnog vijeka. \Na samom početku rada opisana je podjela i osnovne karakteristike mjernih transformatora. Izdvojeni je uljni strujni mjerni transformator tipa AGU, te za taj tip transformatora vezani tehnološki proces, faze i operacije. Opisana je podjela i karakteristike izolacijskih materijala mjernih transformatora s posebnim naglaskom na primjenu transformatorskog ulja. Kemijski sastav i karakteristike transformatorskog ulja sadržanog u mjernom transformatoru određuju se analizom uzorka izdvojenog iz ispitivanog transformatora uzorkovanjem. Ispravnost dobivenih rezultata ovisi o primijenjenoj metodi analize (u ovom slučaju kromatografske analize plinova) i, u najvećem dijelu, o postupku uzorkovanja transformatorskog ulja iz hermetički zatvorenog sistema – uljnog mjernog transformatora. Ukoliko se postupak dosljedno ne provodi prema zadanim normama, dobiveni rezultati uvelike odstupaju od prikaza stvarnog stanja. Povezanost povremene pojave povišene koncentracije vodika otopljenog u transformatorskom ulju i aluminijskih dijelova mjernog transformatora, prihvaćena je nakon izdvajanja razlika i usporedbe sa transformatorima gdje ta pojava uopće ne postoji. Uz podjelu i klasifikaciju aluminijskih legura, u radu su prikazane metalurške osnove povezive uz teorijske mogućnosti nastanka vodika kod aluminijskih legura. Opisane su kemijske reakcije na površini aluminijskih dijelova i prilike za stvaranje vodika prilikom provođenja tehnoloških operacija zavarivanja. Prilikom planiranja pokusa određuje se trenutak provedbe laboratorijskih ispitivanja između raznih tehnoloških operacija i faza. Provedba pokusa simulira fizikalno-kemijske uvjete kojima su izloženi aluminijski (ili drugi dijelovi) kao posljedica primjene određenih tehnoloških faza ili operacija prilikom proizvodnje mjernih transformatora. Uzorci predstavljaju izoliranu utjecajnu cjelinu koja predstavlja ispitivanje točno određenog materijala ili pak tehnološku fazu ili operaciju. Potvrda ili odbijanje pretpostavke o utjecajnosti izolirane cjeline temelji se na rezultatu kromatografske analize plinova otopljenih u hermetički izoliranom sistemu uzorak-transformatorsko ulje.

Abstract (english)

Tough market competition is caused by a number of requirements, the product quality being one of them. The content of dissolved gases in transformer oil is an indicator that can be used to assess the performance of instrument transformers and can serve as an important characteristic for estimating the transformer lifetime. At the beginning of this paper, a classification and basic characteristics of instrument transformers are given, with a special focus on the oil impregnated current transformer, type AGU, along with the related technological process, its phases and operations. A classification and characteristics of insulation materials for transformers are also given, with particular emphasis on the use of transformer oil. Chemical composition and characteristics of the oil contained in each instrument transformer are determined through the analysis of samples taken from the tested transformers. The reliability of test results depends on the applied method of analysis (in this case the gas chromatography analysis) and, for the most part, on the oil sampling from a hermetically sealed system, i.e. the oil impregnated instrument transformer. If the procedure is not consistently carried out according to standards, the obtained results can differ greatly from the actual characteristics of the transformer oil. A correlation between the occurrence of increased concentrations of hydrogen dissolved in the transformer oil and aluminium parts of the transformer has been found through a comparison with transformers in which this phenomenon was not registered. In addition to the classification of aluminium alloys, the paper discusses the conditions of metallurgical processing that could result in the occurrence of hydrogen in the aluminium alloys. Chemical reactions occurring on the aluminium surface (e.g. corrosion) and the chance of hydrogen being created during welding are also described. While planning the experiment, the intention was to determine between which technological phases the laboratory testing should be conducted. The experiment simulates physical and chemical effects of some technological processes applied during the various production phases of the transformer on its parts, particularly those made of aluminium alloys. The samples represent isolated units on which a test of specific materials as well as a test of technological processes can be conducted. In conclusion, the results of chromatography analysis of gases dissolved in a hermetically insulated system, i.e. the transformer oil, are used to test the hypothesis that these isolated units have a significant influence.

• Keywords: Aluminij; aluminijske legure; mjerni transformator; transformatorsko ulje; vodik; korozija aluminijskih legura; zavarivanje; poroznost; vakuumsko sušenje
• Keywords (english): aluminum; aluminum alloys; instrument transformer; transformer oil; hydrogen; corrosion of aluminum alloys; welding; porosity; vacuum drying
• Language: croatian
• URN:NBN: urn:nbn:hr:235:163663
• Study programme: Title: Mechanical Engineering - mr.sc.; Study programme type: university; Study level: postgraduate; Academic / professional title: magistar znanosti (magistar znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-01-04 12:05:18