Hellsjöns kraftverk

The world’s first commercial transmission of electricity using three-phase power for industrial operation took place on 18 December 1893 in the small village of Hällsjön, a modest industrial settlement at the outlet of Lake Vasselsjön, some fifteen kilometres south of Ludvika. One could scarcely imagine something so remarkable happening here, deep in the forests of the Finnmark.

And had it not been for Jonas Wenström, it might never have happened at all – at least not here.

Since the Middle Ages, mining and iron production had been the dominant industries in the region. Power was needed to raise ore from the mines and to pump water out of damp mine shafts. Power was also required to drive the great bellows that blasted air into the blast furnaces. Until the end of the eighteenth century, only the muscle power of strong labourers or obedient horses had been available. But in 1778, the great waterwheel, together with its rod system, was constructed to transfer the force of flowing water to these tasks.

Electricity had been known for many hundreds of years, yet it was not until the late nineteenth century that inventors began to understand how to harness it and construct machines powered by electrical force.

One of the inventors who wished to devote his life to developing machines driven by electricity rather than water power or steam was Jonas Wenström.

He was born in Värmland in 1855. From childhood, those close to him recognised that he possessed an unusually brilliant mind. Yet many people did not take him entirely seriously because his skeleton had been deformed after suffering from rickets as a child. As a result, he often kept to himself, and in solitude he dreamed of building a machine that could illuminate a room even more effectively than paraffin lamps.

During his years of study, he occupied himself with technical problems, attempting to design an electric light bulb, a gyrocompass, threshing machinery, a milk separator, electric irons, dynamos, and much else besides.

However, many inventors at this time were working on electrical devices. One of them was Thomas Edison, who secured the patent for the light bulb before Wenström could.

Instead, Jonas Wenström took work as a technical consultant in his father’s company, where he also had the opportunity to pursue his own inventions.

In 1882, he demonstrated his first invention – an electrical generator he called The Tortoise. In a dark workshop inside a mill, he had gathered a small crowd to witness the demonstration. But when he attempted to switch it on, nothing happened. Jonas felt the weight of failure wash over him. Would this invention too prove worthless? Yet his assistant, Axel Rehli, realised what had gone wrong. Quickly removing an earth wire, he restored the connection, and suddenly the lights came on.

Today, it is difficult for us to imagine the sense of wonder that such brilliant light must have inspired when the entire mill was illuminated.

Jonas sold his patent to the banker Ludvig Fredholm, who founded the company Elektriska Aktiebolaget in 1885. In time, Jonas and his brothers established a business specialising in power transmission. Eventually, these two companies merged to become ASEA – Allmänna Svenska Elektriska Aktiebolaget.

In 1892, Hällsjö power station entered negotiations with ASEA to purchase one of Jonas Wenström’s inventions: the construction of a three-phase power transmission system from Hällsjön to Grängesberg, where the London financier Ernest Cassel was modernising and expanding the entire mining district and required electricity for the undertaking.

On 5 January 1893, a contract was signed under which ASEA undertook to construct a power station at Hällsjön with two generators for power, one generator for lighting, and one reserve generator for either lighting or power production.

But generators alone were not sufficient at Hällsjön. A brick building with rounded-arch windows also had to be constructed, with the machine hall occupying the northern section. A villa was built as accommodation for the machine operators.

Several small lakes also had to be regulated in order to achieve a sufficient head of water of 43 metres, ensuring an adequate water supply. All this was done so that the mining community of Grängesberg could benefit from electricity generated at Hällsjön.

On 18 December 1893, the new power station was inaugurated. It was a great day in the history of both Hällsjön and Grängesberg. Never before had electricity been successfully transmitted over such a distance using three-phase alternating current for commercial use. Would it work?

The invited guests gathered in the beautifully decorated mining office. A lavish meal had been prepared for everyone, including representatives from ASEA, engineers, officials, and employees of the Grängesberg Mining Company.

Engaging speeches were delivered about the exciting new technology capable of transmitting electricity via a 15-kilometre power line to the mining community of Grängesberg, as well as about how the project had been carried out. To ensure that everyone truly appreciated what was taking place, the blinds had been drawn so that only the new electric lighting illuminated the room.

Everything seemed almost like a fairy tale – until the room was suddenly plunged into darkness. Once again, an earth connection had disrupted operations.

Yet after a few adjustments, everything functioned perfectly, and continued to do so. Before the end of the century, around fifty similar systems had been built across Sweden.

Jonas Wenström was bedridden with pneumonia during the inauguration and sadly did not live to witness the success achieved by his three-phase system. He died a few days later.

To this day, Hällsjö power station continues to generate electricity. Thanks to the large water pipes, measuring two metres in diameter, almost all available water can be utilised so that no energy is wasted, unlike many other hydroelectric stations where substantial amounts of water are allowed to pass unused.

The power station has also recently modernised its machinery, and the new equipment was connected to the grid on 3 March 2026, which, based on the name day celebrated in Sweden on that date, meant that the агрегat was given the name Gunvor.