Most of the transformers in service in Europe today were installed nearly 50 years ago and are reaching the end of their functional lifetimes. Simultaneously, deregulation of the power industry has led to increasing competition, favouring lower prices for consumers but resulting in less money available for capital investment and maintenance. So-called blackouts are increasingly common and there is an urgent need to extend the life of existing transformers while improving their reliability. Oil is often used to provide insulation among internal parts of the transformer as well as to cool it and is arguably the most influential factor in extending the service life of transformers. European researchers working on the Transman project sought to produce an automated power transformer oil insulation monitoring and treatment system. In particular, they set out to develop low-cost online dehydration and particle removal technologies for transformer oils. To this end, investigators developed an online moisture removal system from recyclable packing material as an alternative to conventional materials that must be disposed as chemical waste. Another development was novel real-time optical particle sensor to illuminate the oil sample, minimising light scattering and maximising contrast for enhanced detection. Rotation of porous membranes in the particle filtration unit caused turbulent flow of particles across the membrane surface, minimising particle deposition and pore blockage with respect to conventional cross flow filtration units. Researchers also developed intelligent transformer management software to enable online real-time data analysis. Transman has delivered a cost-effective, compact prototype device for power transformer oil insulation monitoring and treatment. Further research should facilitate full exploitation of the significant market potential, enhancing the competitive edge of small and medium-sized enterprises (SMEs) working in the power industry while ensuring reliable energy supply to consumers throughout Europe.