Transmitting power: from the Million-Volt Transformer to Supergrids

The development of renewable energy alongside urbanisation and population growth has made the transmission of electricity a pressing issue for policymakers. Urban centres are often located hundreds or thousands of kilometres from the source of energy, and unlike fossil fuels, renewables cannot be transported. In response to this challenge, “supergrids” are being developed using specially built cables using direct current as very high voltages (HVDC), allowing large volumes of electricity to be efficiently transported over long distances.

The development of supergrids in the 21st century is the continuation of efforts since the dawn of the electric age to increase capacity and scale up access to electricity. As early as Expo 1904 in St. Louis, Chester H. Thordarson showcased a half-million volt transformer, winning a gold medal for the invention which he built in only 28 days. But it was not until Expo 1915 in San Francisco that Thordarson set the bar for electrical transmission when the public were introduced to the million-volt transformer, part of the High Tension Research Pavilion within the Machinery Palace.

Drawn in by the mix of adventure and novelty shown in the glowing corona over the building, over two thousand visitors attended the spectacular public demonstrations of the transformer each day. Daring visitors could walk underneath the charged demonstration screens suspended above the ground, to get closer to the mysterious power of the machine that was designed to handle 1000kW of electricity, equivalent to 1,300 horsepower.

The million-volt transformer became one of the most successful and memorable exhibits that not only portrayed an advancement in technology, but entertained and instructed the crowds. Visitors could, for the first time, experience the electro-static charge from the transformer by tossing a metal ball and seeing it turn into a shooting star. They could also stand under highly charged wires and experience electricity of 75,000 volts pass through their bodies without suffering any harm, giving a curiously thrilling experience.

The iconic transformer showcased at Expo 1915 was an innovation in the way electricity could be used, but it was also an example of a work-in-progress, with the voltage lost demonstrating the limits of transformer technology of the time. Nevertheless, Thordarson’s creation was an essential element for the continued improvement and development of modern energy transmission. The increasingly high capacity required by the modern world is provided by ever more innovative and intelligent power grids, and advanced insulators.