Examensarbetet har utforts pa uppdrag av enheten for Data- och Elektroteknik pa skolan for Teknik och Halsa, KTH. Denna studie om transformatorer omfattar deras funktioner och anvandningsomraden, hur de ar uppbyggda, hur karnan och lindningarna som ar transformatorns viktigaste delar ar uppbyggda, vilka materiel som anvands vid konstruktion av dessa samt vilka typer det finns av dem beskrivs i rapporten. Vidare beskrivs flera olika transformatortypers funktioner och anvandningsomraden. Eftersom en viktig del av studien varit pa vilka satt transformatorer kan utvecklas for okad miljovanlighet och livslangd gar rapporten igenom olika vegetabiliska oljor, vilka fordelar de har gentemot mineraloljor och vilka egenskaper de har samt pa vilket satt de ar skonsammare mot miljon. HVDC-enheter transformerar hoga spanningar fran vaxelspanning till likspanning for mindre resistiva forluster och darmed lagre energiforluster vilket i sin tur leder till en renare miljo. Teorigenomgangen av transformatorn ligger till grund for utformningen av en laboration for undervisningsbruk, bl.a. i en kurs om elkraftteknik som ges i hogskoleingenjorsprogrammet Elektroteknik pa KTH. / This degree project was carried out on behalf of the unit for Computer and Electrical engineering at the School of Technology and Health, KTH. This study about transformers, their function and uses, the way they’re built, how the core and windings, which are the most important parts of a transformer, are made and what kind of materials are used to make them. Several types of transformers and their functions are described. A crucial part of the study has been to search for different ways to develop transformers to make them environmentally safer and to increase their life-span. As such this work describes different transformer oils, what advantages and disadvantages they have compared to mineral oils, what properties they have and in what way they’re less harmful for the environment. HVDC units transform high voltages from Alternating Current to Direct Current to lessen the resistive losses and energy losses which lead to a cleaner environment. The theory examination of the transformer is the basis for the formation of a lab for educational use, among others in a course about electrical power that’s included in Bachelor of Science in Electrical Engineering at KTH.