Miniature Circuit Breaker ‘hidden hero’

19-06-2024

Miniature Circuit Breaker ‘hidden hero’ enabling energy transition built on 100-year safety legacy

• 100 years from inception, innovation in electrical safety technology becomes central to a safe net zero journey as renewable energy sources require grid management

• ABB’s first-of-its-kind MCB continues to set industry standards for performance, compact size, connectivity, and transparency

• Flexible, time-saving designs enable easier installation helping address the current industry skills shortage

ABB’s first-of-its-kind Miniature Circuit Breaker (MCB)* reaches a milestone 100-year anniversary of protecting electrical circuits and evolves to meet the sustainability needs of the future. With nearly a quarter of all fires occurring in residential buildings, the MCB not only revolutionized the way we live by enabling safe homes, but brought electrical safety throughout society, from rail infrastructure through to factories, commercial buildings, and data centers.  

MCBs detect electrical faults like short circuits and overcurrents, disconnecting the circuit within 10 milliseconds, 10 times faster than the blink of an eye. It can then be quickly and easily reset without the need for it to be replaced. As we transition towards a net zero future, it is essential to increase electrification and integrate more diversified, renewable energy sources. This means protection devices have even greater electrical loads to manage along with variations in power supply and demand. ABB  provides electrical safety to everything from solar panels and heat pumps to electric vehicles and brings additional protection against faults like residual currents, surges, earth fault currents, or arc faults.

Aldo Sciacca, Head of Energy Distribution, ABB Electrification’s Smart Buildings Division, says, “Our future-focused portfolio centers on achieving energy efficiency and transparent, sustainable practices. We also focus on easy installation which is invaluable when facing skilled labor shortages. Through our compact, modular, and flexible designs, we’re enabling buildings to be retrofitted and to integrate renewable energy sources, quickly and safely. This plays a vital role in ensuring the safe development of sustainable, modern communities, cities, and urban landscapes of our future.”

Today’s protection devices make new and old buildings around the world safer, smarter, and more sustainable. Compact designs enable, retrofitting even in historical buildings where space is limited. The wooden structures within many of the world’s historically significant buildings such as the Kinderdijk Windmills in the Netherlands, and the Aachen Cathedral in Germany, are particularly vulnerable to electrical hazards, which can lead to fires. Electrical systems have been updated in these UNESCO World Heritage sites with the installation of compact protection devices like Arc Fault Detection Devices (AFDDs) that have an integrated Residual Current Circuit Breaker with Overcurrent protection (RCBO), protecting these cultural landmarks for centuries to come.

About the history

The evolution of MCBs - timeline

Hugo Stotz & Patent of first resettable Miniature Circuit Breaker (MCB)

Hugo Stotz at his electrical supplies company in Mannheim, Germany

Today's facility at ABB-STOTZ Kontakt GmbH, Heidelberg, Germany

In 1918, ABB’s forerunner, Brown, Boveri & Cie (BBC), purchased Stotz Kontakt, an electrical supplies company based in Mannheim, Germany. The company’s founder, Hugo Stotz stayed on with BBC and, working with his chief engineer, Heinrich Schachtner, invented the first resettable Miniature Circuit Breaker, a device that was patented in November 1924.

By combining thermal and magnetic trips into a single, reusable unit, the MCB was patented in 1924, becoming capable of switching off high currents and becoming resettable, meaning devices didn’t have to be repeatedly replaced. Today, ABB has eight factories globally manufacturing MCBs with more than 100 million poles per year.