Stefan Tenbohlen studied general electrical engineering at RWTH Aachen and obtained his doctorate in 1997 with a dissertation on the subject of the insulation strength of sulfur hexafluoride. From 1997 to 2004 Stefan Tenbohlen worked for ALSTOM Schorch Transformatoren GmbH in Mönchengladbach, where he became head of product and basic development in 1997. In this position he was responsible for developing online monitoring systems for condition diagnosis of power transformers. From 2002 to 2004 he was head of the division for the development, calculation and design of power transformers.