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A day out of the ordinary in Ludvika

 


Some places feel engineered for innovation. Ludvika is one of them.

Väsman Lake, Ludvika

I have always said that things happen for a reason. Whatever that reason is, there is always something you can extract and learn from.  

On Friday 12th of September 2025, I took a night train from Skåne up to Dalarna. The mission? Attending a massive open house at Hitachi Energy in Ludvika. One of those events that when you know it's happening, attending becomes non-negotiable. Before the big day, I decided to read a bit about the area itself, since there were some remarkable things that could not remain obscure to me if I were to visit it.

Why Ludvika?

Turns out, Ludvika has been a global hub for high-voltage technology for decades. The site is completely tied to the development, manufacturing, testing and shipping of high-voltage engineering such as HVDC. Just imagine, the combination of manufacturing, testing and research, all in one place.
Ludvika has been leading the power industry for over a century; a leadership built on over 1000 years of mining heritage, which has been the foundation of the Swedish economy since the 10th century. The beginning of the electrical industry in Ludvika dates back to 1900, initially founded as Elektriska Aktiebolaget Magnet. It was in this year when the factory was established, providing the region with products for electric power, revolutionizing the mining industry...and the world. 


A world center of high voltage in Ludvika
(Jan G. Johansson, 2015)

In 1997, the first HVDC Light test connection between Hällsjön and Grängesberg in central Sweden marked the start of a completely new power transmission technology. It was the birth of VSC-based HVDC. This was an experimental project or proof-of-concept, transmitting 3 MW at approximately 10 kV over 10 km. Practical conditions to validate switching, control strategies, cable behaviour and integration into a low-voltage environment. Ludvika was the core R&D and manufacturing site of ASEA (Allmänna Svenska Elektriska Aktiebolaget). At that time, it was Sweden's major electrical engineering company and one of the world leaders in high-voltage technology, transformers, generators, industrial automation and early HVDC development. ASEA later became ABB and today, that legacy lives on in Hitachi Energy.


Saturday, 13 September 2025

On this day, the facility opened its doors to the public. A massive turnout —  and me briefly getting lost on the way to the main entrance — the day got off to a great start. 

Before beginning the factory tour, I paused for a moment to capture what I would call an iconic shot:


Zento Garden, Ludvika


HVDC Converter Transformer

This massive yet impressive monument is a testament to Ludvika's pioneering role in global power transmission. This unit represents a High Voltage Direct Current (HVDC) converter transformer, used to transmit electricity over long distances via overhead power lines or submarine cables. This technology also enables the interconnection of independent power systems. The main components are:

  1. Transformer tank (rectangular steel enclosure housing the core and windings)
  2. Elevated seat + Grid-side bushing 
  3. Valve-side bushings (the two giant ''arms'')
  4. Corona shields (rounded ends)
  5. Transformer-mounted surge arrester (electrically close to the equipment they protect)
Impressive views from any angle

A well-known example of interconnection between two power systems is NordLink, which is a subsea 1,400 MW HVDC power cable between Norway and Germany. This allows Germany to rely on Norway's vast hydropower, effectively acting like a huge battery and supporting Germany's demand when wind farms provide insufficient output due to the fluctuating nature of the wind. Another subsea electrical interconnector is IFA-2 between France and the UK. 

The working principle consists of:

  • taking three-phase power
  • converting AC to DC using a converter station
  • transmission
  • converting DC to AC at a receiving station to feed the grid


Power flow of a Line-Commutated Converter (LCC-HVDC)
 (Wesam Taha, 2015)


Troll A, a real-world, industrial-scale example of HVDC Light
(Wesam Taha, 2015)


HVDC is suitable for very long-distance transmission of large amounts of power with reduced losses, operating between 80 to 1,100 kV (DC) or up to 1,200 kV (AC). Despite higher upfront costs mainly due to converter stations, there is a critical distance beyond which HVDC transmission becomes economically attractive compared to conventional AC transmission.


HVAC vs HVDC cost curves
(ABB, Special Report)

The experience

As a visitor there were different paths for me to explore such as: capacitors, service, bushings, surge arresters, high-voltage circuit breakers, and the HVDC Test Center. I started my self-guided at the 
Uno Lamm HVDC Center.



Uno Lamm HVDC Center entrance

It is here where control equipment is tested and key components such as valves, shunt reactors, and optical fibers are manufactured.

Taking pictures was generally not permitted inside unless explicitly stated but several highlights of my tour stood out. One of them was a live demonstration in one of the high-voltage test halls operated by STRI, a leading independent test laboratory based in Ludvika, within the climate test hall (Klimattesthallen).

Here, STRI specialists push high-voltage components and systems to their limits. The scope includes: 

  • dielectric withstand tests
  • HVDC testing
  • pollution and environmental testing
  • cable testing
  • temperature-rise tests 
  • multiple stresses testing
  • snow and ice testing
  • type testing

STRI operates five large indoor high-voltage test halls, as well as an outdoor test area that includes an underground facility for pre-qualification testing of HVAC and HVDC cables. In addition, a circular climate test hall is equipped with steam-fog generators and salt-fog ramps, allowing tests to be carried out under controlled environmental conditions at temperatures ranging from -10 to +55 °C. 

On this occasion, I witnessed a controlled sphere-gap discharge demonstration, producing a visible lightning-like arc at around one megavolt (1 MV). The setup illustrated air breakdown under extreme electric-field stress, mimicking overvoltage events such as lightning and switching surges. You get an idea of the severe stress insulation systems must withstand in real-world operation. 

Seeing these phenomena live was one of the highlights, showing high-voltage engineering in a way no textbook ever could.

For a visual impression of this demonstration, watch this video. The video segment between 0:08-0:11 captures it beautifully! 

Fun fact: I couldn't stop watching that video. The sound effects make the physics surprisingly intuitive, and the visual impact is striking! Later that day I tried to find the video online without any luck. It turns out it was released only earlier this month. A small but satisfying rediscovery.



The evening before the Open House, I arrived in Ludvika expecting a quick meal in a lively local spot. It unexpectedly turned into a long conversation at a local bar with a few charming locals. Good food, good company, and a reminder that engineering hubs are built around people. 



It was most certainly a day out of the ordinary. 
Tack tack, Ludvika!



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