Patent issued 90 years ago
This year, ABB celebrates the 90-year anniversary of the circuit breaker patent. Invented by Hugo Stotz in 1923, the world’s first miniature circuit breaker (MCB) combined thermal and magnetic trips unit into one device. He developed a reusable device, which was able to switch off high currents without destroying the fuse. And in 1924, he received the patent for his invention.
Today’s world of electricity would not be possible as we know it because without an MCB, a fuse would have to be replaced with each overload. Due to the miniature circuit breaker, your PC, TV, refrigerator and other appliances can operate safely for many years because any harmful currents are detected by the MCB and instantaneously interrupted. And all you need to do is to flip up the switch that has tripped.
Approaching 1 billion production
Last year, ABB STOTZ-KONTAKT manufactured some 42 million MCB’s at its production plant in Heidelberg, Germany. Since production started in 1928 that adds up to more than 950 million circuit breakers, and by 2015, ABB expects to break the one billion mark.
1. 1923 First miniature circuit breaker (MCB) | 2. 1928 Legacy MCB with K-characteristics for motors | 3. 1957 High-efficiency legacy MCB S201-K4 | 4. 1961 Legacy MCB S161 | 5. 2012 MCB from System pro M compact S200 |
Faster than the blink of an eye
The first breaker was a great success as it could easily be screwed into the existing fuse base and no changes were required to the electrical installation. In 1928, STOTZ also developed a special circuit breaker for coping with loads of higher starting currents such as motor applications. This opened the door for applications in industrial settings, where the MCB is found today as abundantly as in households. Over the years, the ABB STOTZ-KONTAKT company continuously improved the breaker technology and kept up with technology standards, such as the DIN-Rail in 1970 making it even easier to install.
Today, when the ABB circuit breaker reacts to short circuits or overloads, it trips and interrupts the current within 10 milliseconds. When this happens, the breaker is exposed to intense heat ranging 5,000-6,000 degrees Celsius – capable of melting rocks – but easily reacts 10 times faster than the blink of an eye.