Analiza kompozitnih šupljih izolatora u mjernim transformatorima laboratorijskim ispitivanjima i metodom konačnih elemenata

master's thesis

• Title (english): Analysis of composite hollow insulators in instrument transformers by laboratory tests and finite element method
• Author: Marin Erceg
• Mentor: Irena Žmak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-07, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Potreba za električnom energijom je svakim danom sve veća, a samim time je i potreba za uređajima za distribuciju, pretvorbu i sigurnu uporabu električne energije sve veća. Takvi uređaji su transformatori. Vrsta transformatora koji su zaduženi za upravljanje, nadzor i zaštitu distributivnih mreža su mjerni transformatori. Mjerni transformatori dijele se na strujne, naponske, kombinirane i specijalne i oni pretvaraju prvotno izmjerene struje i napone na vrijednosti koje su prikladne za... More mjerenje. Zbog svoje specifične, vitke, konstrukcije su mjerni transformatori skloni lomu. Najkritičniji dio transformatora je izolator. Izolator se proizvodi od porculana ili od kompozita, a sve više se teži kompozitnim izolatorima zbog manje mase i nekih boljih mehaničkih svojstava materijala. Kompozitni izolatori se proizvode u izvedbi laminiranog kompozita s različitim tehnologijama namatanja vlakna ojačala u matricu. Končar naručuje izolatore od provjerenih proizvođača, ali je tehnologija proizvodnje poslovna tajna pa točna mehanička svojstva kompozita koja služe za valjanu analizu nisu poznata. U ovom diplomskom radu provedeno je laboratorijsko ispitivanje izolatora u Končarevom Institutu prema normi HRN EN IEC 61462:2023. Tri tipa izolatora proizvedenih različitim tehnologijama su prema normi bili podvrgnuti na savojno opterećenje koje je dominantno kod izolatora. Također je napravljena FEM-analiza u svrhu usporedbe rezultata. Željeni ishod je bio zamijeniti skupo laboratorijsko ispitivanje brzom i jeftinijom analizom konačnih elemenata. FEM-analiza je provedena u Ansysu gdje su postavljeni svi potrebni rubni uvjeti i opterećenja. Rezultati dobiveni s Instituta dosta su se razlikovali od rezultata dobivenih numeričkom metodom konačnih elemenata. Zaključak koji se može donijeti je da FEM-analiza daje zadovoljavajuće rezultate u usporedbi s eksperimentalnim ispitivanjem, ali i da su potrebna poboljšanja. Potrebno je definirati daljnji slijed ispitivanja ili novu metodu ispitivanja gdje bi se uklonili potencijalni čimbenici koji negativno utječu na krajnje rezultate analize i ispitivanja. Predložene promjene su uklanjanje inicijalnog opterećenja, dodavanje više uzoraka prilikom ispitivanja te, ako je moguće, provjera mehaničkih svojstava kompozita dobivena od proizvođača kako bi se unijeli točni podatci i samim time se osigurala točnost FEM-analize. Less

Abstract (english)

The demand for electrical energy is increasing daily, and consequently, the need for devices for the distribution, conversion, and safe use of electrical energy is also growing. Such devices are called transformers. A type of transformer responsible for the management, monitoring, and protection of distribution networks is the instrument transformer. Instrument transformers are divided into current, voltage, combined, and special transformers. They convert initially measured currents... More and voltages into values suitable for measurement. Due to their specific, slender construction, instrument transformers are prone to breaking. The most critical part of the transformer is the insulator. Insulators are made of porcelain or composite materials, with a growing preference for composite insulators due to their lower weight and some of their better mechanical properties. Composite insulators are made in the form of laminated composites with different fiber – winding technologies. Končar orders insulators from verified manufacturers, but the manufacturing technology is a trade secret, so the exact mechanical properties of the composites used for a valid analysis are unknown. In this Master’s thesis laboratory testing of insulators was conducted at the Končar's Institute according to the HRN EN IEC 61462:2023 standard. Three types of insulators, manufactured using different technologies, were subjected to bending loads, which are dominant in insulators, according to the standard. A finite element method (FEM) analysis was also conducted for comparison. The desired outcome was to replace expensive laboratory testing with a faster and cheaper finite element analysis. The FEM analysis was performed in Ansys, where all necessary boundary conditions and loads were set. The results obtained from the Institute differed significantly from those obtained by FEM. The conclusion that can be drawn is that the FEM analysis gives satisfactory results compared to the experimental test, but also that improvements are needed. It is necessary to define a further testing sequence or a new testing method to eliminate potential factors that negatively impact the final results of the analysis and testing. The proposed changes include removing initial loading, adding more samples during testing, and, if possible, verifying the mechanical properties of the composite provided by the manufacturer to ensure the accuracy of the FEM analysis. Less

• Keywords: mjerni transformator; kompozitni izolator; mehanička svojstva laminiranog kompozita; teorija laminata; FEM-analiza; laboratorijsko ispitivanje; usporedba rezultata
• Keywords (english): instrument transformers; composite insulator; mechanical properties of laminated composite; lamination theory; FEM analysis; laboratory testing; results comparison
• Language: croatian
• URN:NBN: urn:nbn:hr:235:366250
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2029-07-11
• Created on: 2024-07-11 20:25:46