The transformer is one of the most common and most important electric machines for power companies. Cost of investment and the economic worth of a transformer are counted in millions of SEK. Because of that, proper maintenance actions that may lead to longer technical life time should be the aim in all situations. The aim with the report was to perform transformer diagnosis by dissolved gas analysis on Umeå Energi AB´s power transformers and a risk assessment. The report should also contribute to longer life time for the transformers. Oil samples were taken from each transformer two times. The first sample in summer 2013 and the second in April 2014. The gas concentrations in the samples was measured by an portable gas analyzing monitor. The samples were analyzed regarding to gas concentrations and the gas rate of change. The analyze was based on scientific methods like the total amount of dissolved combustible gases, Duvals triangle and Rogers ratios. The risk assessment was made as an internal comparison between Umeå Energi´s transformers. The results of the study showed large gas concentrations in several transformers in both times of sampling. The high concentrations appeared in old as well as in newer transformers. Therefore can the presence of gases not only be explained by natural aging, and different fault types can be suspected in some of the transformers. Duval´s triangle and Rogers ratios indicated various fault types. One of the transformers was immediately taken out of service after the first sample because of high level of a separate gas and the discussion about what actions to take was ongoing. A number of other transformers were taken into further consideration. Conclusions of the report were that transformer diagnosis is a very complex science where it is important to collect as much adequate information as possible to be able to make a correct analyze for every single transformer and to take proper actions. To be able to secure fault free operation of the power grid and to minimize the risk of wasting economic and material resources, and from a personal safety point of view, the power transformers must be maintained and tested regularly and be based on scientific principles. Faults in power transformers can lead to large impact on the environment and large effect on society if electricity is not available.

Hitachi ABB Power Grids is a world leading manufacturer of power transformers, operating on an increasingly competitive market. With the advancements in digitalization and electrification, the production of power transformers has been subject of higher demands, both in terms of product quality and production efficiency. To stay ahead of market rivals, constant development of the business and its production processes is necessary, which has been enabled by increased access to innovative technical solutions. Novel appliances and areas of development has been investigated, of which 3D-scanning is one of the promising technologies that has proven useful in the manufacturing industry.  The purpose of this study has been to map the production process of power transformer manufacturing at Hitachi ABB Power Grids, with the intention of identifying potential areas for use of 3D-scanning technology in quality management. By analyzing each individual production segment, the study has sought to answer to where in the production system that 3D-scanning technology can be beneficial, what type of improvements it can contribute with, and what risks and limitations that using the technology might entail.  The results were obtained by analyzing empirical data, collected through both qualitative and quantitative methods. Interviews with employees and on-site observations has been the main sources of data, together with documentation and statistics from the company’s own data bases.  Central factors that the analysis was built upon are the registered costs of failure and reported quality defects, combined with the appropriateness of 3D-scanning technology in each segment regarding the practical usability, advantage in time, economic profitability, and the feasibility of implementation in the production system. A value assessment was made of the device’s potential, leading to identifying improvements in transparency, traceability, and efficiency. Some of the discussed drawbacks were limited visual access, faulty handling of the equipment, and excessive reliance on the technology. / Hitachi ABB Power Grids är en världsledande tillverkare av krafttransformatorer, agerandes på en alltmer konkurrensbenägen marknad. Med digitaliseringens och elektrifieringens framfart ställs högre krav på produktionen av krafttransformatorer, både gällande produktkvalitet och produktionseffektivitet. För att bibehålla en ledande position krävs därför ständig utveckling av verksamheten och dess processer, vilket bland annat möjliggjorts av den ökade tillgången till innovativa tekniska lösningar. Nya verktyg och förbättringsområden undersöks, varpå en av de uppmärksammade teknikerna är 3D-skanning, vilket visat sig användbart inom tillverkningsindustrin.  Syftet med studien har varit att kartlägga processen för krafttransformatortillverkning hos fallstudieföretaget Hitachi ABB Power Grids, med avsikt att identifiera möjligheterna kring användning av 3D-skanningsteknik i kvalitetsarbetet. Genom att undersöka varje individuellt delmoment i produktionsprocessen har studien sökt besvara var i produktionssystemet som 3D-skanningstekniken kan medföra förbättringar, vilken typ av förbättringar som kan åstadkommas, samt de risker och begränsningar som användning av tekniken eventuellt kan medföra.  Resultaten erhölls genom analys av empiriska data som samlats in genom både kvalitativa och kvantitativa metoder. Intervjuer med personal och observationer på anläggningen har utgjort de huvudsakliga källorna till information, tillsammans med dokumentation och statistik från företagets interna databaser.  Centrala faktorer som analysen har byggt på är produktionens registrerade felkostnader och rapporterade kvalitetsfel, i kombination med 3D-skanningsteknikens lämplighet för respektive avsnitt gällande praktisk användbarhet, tidsmässig fördel, ekonomisk lönsamhet och implementerbarhet i produktionssystemet. En värdering gjordes därefter av teknikens potential, och förbättringar i form av transparens, spårbarhet och effektivitet kunde identifieras. Några av de brister som uppmärksammades var begränsad visuell åtkomst, felaktig manövrering av utrustningen och överdriven tillförlitlighet till tekniken.

Mälarenergi’s vision is a world where we live and operate together without climate impact. This degree project has examined which opportunities Mälarenergi Elnät has in order to work towards this vision by looking more closely at whether their bigger substations can become self-sufficient in terms of heating, cooling and battery charging. The purpose of this degree project was to investigate how heat recovery from the substations’ transformers and the installation of PV-systems could contribute to both more environmentally friendly and self-sufficient substations. In addition to that, the economics and how this would affect the Swedish power grid regulation were of interest. The thesis was based on current values and data for oil temperatures and installed power in three of Mälarenergi Elnät’s substations. In addition to this, the thesis also includes a literature study, where previous research in heat transfer from power transformers, up-to-date information about PV-installations and the power grid regulation in Sweden were studied. The results of the thesis showed that both PV-installations and heat exchange for heating the station buildings could be of great benefit for Mälarenergi Elnät. In all but one case, the energy saving measures resulted in lower life cycle costs than if no measures were taken. It shows that the measures investigated in the thesis are not only good from an environmental perspective, but also has economic profitability.