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Customer Success Story

TXpert™ Enabled power transformer - Fortum, Sweden

Digitalized power transformer for Fortum at Sweden's tallest hydropower dam

Fortum’s 120-meter tall Trängslet hydropower dam, in Österdalälven, central Sweden, is one of the country’s largest hydropower plants and its tallest. Our transformer delivers enhanced performance for fossil-free electricity generation at the dam, in a challenging underground location.


With a normal annual electricity generation of 651 gigawatt hours (GWh), there can be no risk of breakdowns or generation stoppages.

The final 1,000 meters of the station's access route is especially challenging, particularly in winter conditions, and in addition the electrical equipment is installed underground, via a steep slope and narrow entrance.


The original transformer, which was also supplied by Hitachi Energy (as ASEA), had been in operation for over 50 years and a one-to-one replacement was needed.

The company selected a 140 megavolt-ampere and 155/16 kilovolt TXpert enabled power transformer, designed as a copy of the original unit. Hitachi Energy’s TXpert transformers are equipped with digital devices to monitor and analyze the their health, enhancing reliability and performance.

The project included transportation as well as on-site installation and final assembly in this challenging location.


A one-to-one solution meant the transformer could be installed without costly electrical, mechanical or structural modifications. In fact, the new transformer is smaller than the old one because the modern technology requires less space, there is less oil in it and the losses are lower. Plus the TXpert digital monitoring collects, compiles and analyzes critical data to ensure that the transformer continuously delivers optimal performance remotely monitored and controlled 370 kilometers away at Fortum's operations center in Stockholm.

“When we choose a supplier, it is not just about buying a good product. As always in projects, you try to prepare for everything, but things change along the way and therefore the relationship with the client is important. We always try to state that projects are tackled together, working towards a common goal.”

- Mikael Andersson, Project Manager at Fortum Hydro

TXpert™ Enabled power transformer at Fortum, Sweden
Main data
Customer: Fortum
Product: Generator step-up transformer
Application: Generation
Rating: 140 MVA, 155 / 16 kV
Location: Sweden

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