A century ago this year, while working at Brown, Boveri & Cie (BBC), the forerunner of ABB, Hugo Stotz and Heinrich Schachtner invented a little device that continues to protect millions of electrical circuits around the world – the Miniature Circuit Breaker (MCB).
Patented back in 1924, the MCB combined a thermal and magnetic trip unit in a single device, protecting electrical circuits from overload and short-circuits by switching off high currents and then resetting, meaning devices didn’t have to be repeatedly replaced.
With nearly a quarter of all fires occurring in residential buildings, the MCB not only revolutionized the way we live by enabling safe homes – it facilitated electrical safety throughout society, from rail infrastructure to commercial buildings and data centers.
Today, eight ABB factories globally are manufacturing MCBs, with more than 100 million poles a year. ABB’s first-of-its-kind MCB, along with other protection devices, continues to set industry standards for performance, compact size, connectivity, and transparency.
A century on from Stotz and Schachtner’s breakthrough, we need MCBs more than ever. With the world transitioning from fossil fuels to clean energy, innovation in electrical safety technology is central to a safe journey to net zero since renewable energy sources require grid management.
MCBs and the energy transition
As distributed and intermittent energy sources such as wind, solar and hydro continue to grow their share in the energy mix1, alongside electric vehicles, storage systems, heat pumps and 5G, 2so demand for electricity becomes increasingly distributed and unstable. This, combined with energy prices and security of supply issues, is piling pressure on infrastructure and the electric grid.
As we transition to net zero by increasing electrification and integrating more diversified, renewable energy sources, protection devices have even greater electrical loads to manage along with these variations in power supply and demand.
At ABB, our MCBs detect electrical faults such as short circuits and overload, disconnecting the circuit within 10 milliseconds – 10 times faster than the blink of an eye. We provide electrical safety to everything from solar panels and heat pumps to electric vehicles, and with our complete range of devices we protect against faults like residual currents, surges, earth fault currents, or arc faults.
Rejuvenating ageing infrastructure
Today’s protection devices make both new and old buildings safer, smarter and more sustainable. Compact designs enable retrofitting, even in historical buildings where space is limited, which is of particular use in Europe, where at least 40 percent of the buildings were built before the 1960s3.
Wooden structures in many of the world’s historically significant buildings such as the Kinderdijk Windmills in the Netherlands and the Aachen Cathedral in Germany, are especially vulnerable to electrical hazards, which can lead to fires.
Updating electrical systems in these UNESCO World Heritage sites with compact Arc Fault Detection Devices (AFDDs) that have an integrated Residual Current Circuit Breaker with Overcurrent Protection (RCBO) will protect them for centuries to come.
Our electrical products and solutions, including MCBs, prioritize compact, modular, and flexible designs, enabling buildings to be retrofitted and to integrate renewable energy sources quickly and safely. From the micro to the macro, such solutions also have a vital role to play in developing safe, sustainable, modern communities, cities, and urban landscapes.
So, a century on from Stotz and Schachtner’s revolutionary innovation, the humble MCBs will play in protecting the energy systems of the future, bringing electrical safety and supporting the journey to net zero.
[1] ABB white paper – ‘A digital path to grid code compliance’ – May 2021
[2] ‘How smart technology is helping make sustainable living a reality’ – Lucy Han, ABB, April 2024
[3] ‘Smart solutions to the issue of buildings emissions’ – Oliver Iltisberger, ABB, August 2021
About the author
Christian is the Global Product Manager for Line Protection Devices at ABB Electrification’s Smart Buildings Division. He is based in Heidelberg, Germany, and joined ABB in 2014. Since then, he has held various roles in the fields of protection devices. Christian holds a Master's degree in Industrial Engineering from the University of Applied Science Mannheim.
