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Web Story 21-09-2021

3 min read

Hitachi ABB Power Grids installs TXpert™ digitalized transformer for Fortum at Sweden’s tallest hydropower dam

Delivering enhanced performance for fossil-free electricty generation in Trängslet in Österdalälven, Sweden, in a challenging underground location.


Fortum’s 120 meter tall Trängslet hydropower dam, in Österdalälven, central Sweden is one of the country’s largest hydropower plants and the tallest in the country. With a normal annual electricity generation of 651 gigawatt-hours, there can be no risk of breakdowns or generation stoppages.

The final 1,000 meters of the dam’s access route is especially challenging, particularly in winter conditions, plus the electrical equipment is installed underground, via a narrow and steep tunnel.

“First and foremost, it is of course about being able to manufacture a transformer that meets our requirements,” says Mikael Andersson, project manager at Fortum Hydro. “It is difficult in terms of transport to get it here, and then adjustments are required to get it underground. As a manufacturer, you can not only offer a standard product, but you must spend time on design to meet our requirements.”


When one of the plant’s transformers began to show signs of being obsolete, Fortum acted immediately. The original transformer, which was also supplied by Hitachi ABB Power Grids (as ASEA), had been in operation for over 50 years and a one-to-one replacement was needed.

A 140 megavolt-ampere and 155/16 kilovolt TXpert enabled power transformer was selected, designed as a copy of the original unit. Hitachi ABB Power Grids’ TXpert transformers are equipped with digital devices to monitor and analyse the health of the transformer, enhancing reliability and performance.

The project included transportation plus on site installation and final assembly in this challenging location.

“There were many risks to take into account, but everything went well. When we choose a supplier, it is not just about buying a good product, it is also important to know that the subcontractors who are hired to handle the transformer know their stuff,” said Mikael Andersson. “The collaboration worked well. 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 done together towards a common goal.”


The 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.

The transformer operation in Trängslet is now secured and handed over to Fortum's operations center, remotely monitored and controlled 370 kilometers away in Stockholm.

About Fortum
Fortum is one of the country's largest hydropower producers, with more than 150 hydropower plants in Sweden and Finland. With a 70 km long reservoir, Trängslet in Österdalälven is one of Sweden's largest hydropower plants. The impressive 120-meter-high dam is the highest in the country.

About TXpert
TXpert is an open, scalable, manufacturer-agnostic ecosystem for digitalization of transformers, designed to drive data-driven intelligence and decision making in the operations and maintenance of transformers and power grids.  

It is a complete suite of products, software, services and solutions that work together and have the capability to integrate with new and existing digital equipment from other manufacturers.

View of the installed transformer
View of the installed transformer

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