A brief history of transformers (not the robot type)


I still have disliked exaggerated claims of impending scientific and technical breakthroughs, such as cheap fusion, cheap supersonic travel, and terraforming other planets. But I love the simple devices that do a lot of the foundational work of modern civilization, especially those that do it modestly – or even invisibly.

No device fits this description better than a transformer. Non-engineers may be vaguely aware that such devices exist, but they have no idea how they work and how absolutely essential they are in everyday life. (A transformer is a device that transfers electricity between two circuits while changing the voltage, that is, the “pressure” of the power of the electric current.)

The theoretical foundations were laid in the early 1830s, with the independent discovery of electromagnetic induction by Michael Faraday and Joseph Henry. They have shown that a changing magnetic field can induce a current of a higher voltage (called “step up”) or lower (“step down”). But it took another half a century before Lucien Gaulard, John Dixon Gibbs, Charles Brush and Sebastian Ziani de Ferranti could design the first prototypes of useful transformers. Then, a trio of Hungarian engineers – Ottó Bláthy, Miksa Déri, ​​and Károly Zipernowsky – improved the design by building a toroidal (donut-shaped) transformer, which they exhibited in 1885.

The following year, better design was introduced by a trio of American engineers – William Stanley, Albert Schmid and Oliver B. Shallenberger, who worked for George Westinghouse. The device quickly took the form of the classic Stanley transformer which has been preserved ever since: a central iron core made up of thin strips of silicon steel, one part in the shape of an “E” and the other in the shape of an “I”. To make it easier to slide the coiled copper coils into place.

In his address to the American Institute of Electrical Engineers in 1912, Stanley rightly marveled at how the device offered “such a complete and simple solution to a difficult problem.” It shames all mechanical attempts at regulation. It manages with such ease, certainty and economy vast loads of energy which are instantly given to it or taken from it. It is so reliable, solid and certain. In this mixed steel and copper, extraordinary forces are so well balanced that they are almost unsuspected.

The greatest modern incarnations of this sustainable design have made it possible to deliver electricity over great distances. In 2018, Siemens delivered the first of seven record 1,100 kilovolt transformers that will supply electricity to several Chinese provinces connected to a high-voltage DC line nearly 3,300 kilometers long.

The number of transformers has exceeded anything Stanley could have imagined, thanks to the explosion of portable electronic devices that need to be recharged. In 2016, global smartphone production alone exceeded 1.8 billion units, each supported by a charger housing a tiny transformer. You don’t need to disassemble your phone charger to see the heart of this little device; a complete disassembly of the iPhone charger is posted on the internet, with the transformer being one of its larger components.

But many chargers contain even smaller transformers. These are non-Stanley (i.e. unwound) devices that take advantage of the piezoelectric effect – the ability of a crystal forced to produce a current, and a current to warp or deform a crystal. Sound waves hitting such a crystal can produce a current, and a current passing through such a crystal can produce sound. One current can in this way be used to create another current of a very different voltage.

And the latest innovation concerns electronic transformers. They are much reduced in volume and mass compared to traditional units, and they will become particularly important for integrating intermittent sources of electricity – wind and solar – into the grid and for enabling DC micro-grids. Without transformers, we wouldn’t be the age of ubiquitous electricity and we wouldn’t be stuck in the age of oil lamps and the telegraph.


Of Numbers don’t lie by Vaclav Smil, published by Penguin Books, a brand of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2020 by Vaclav Smil.


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