Air Circuit Breakers: An Evolution
Who knew anything about circuit breakers before World War II? No one. Back then, the way people would break a circuit was with a fuse. Fuses were effective, but they were not smart. They had to be replaced after a circuit became overloaded.
The First Circuit Breaker
With the war effort, the world saw the first reusable fuse: The circuit breaker. All the major manufacturers during World War II began to use them. But these first industrial circuit breakers were big and heavy, as they had to be mounted on large pieces of slate, which at the time was considered the best non-conductive material. The massive contacts would open on overload when two small disks, submerged in oil, would break apart. The principle behind this early tripping mechanism was that the oil in a “dashpot� would heat up, become more viscous, and eventually the two discs submerged in this oil would break apart as the current increased. It was a working solution, but primitive by our standards today.
Plastics Improve Circuit Breaker
The 1950s saw an era where plastics became a larger part of our everyday lives. Plastic was also a great nonconductive material, and was the reason for the greatest changes in the circuit breakers of that generation. The breakers became smaller and lighter. The tripping mechanism, once a dashpot submerged in oil, was now an electro-mechanical unit.
Electric Control Supplies GE, Westinghouse, Siemens-Allis, ABB, Federal Pacific, Cutler-Hammer and ITE Circuit Breakers
Remanufactured Industrial Circuit Breakers for Buildings Built Prior to 1955
The other major issue was that early circuit breakers were in no way interchangeable with products made in 1945, as all the parts were completely different. Buildings built prior to 1955, for example, had the first generation of obsolete circuit breakers. Building owners could not get parts, spare breakers or support from the original equipment manufacturers. They had to buy remanufactured circuit breakers to go with their obsolete switchgear.
Remanufacturing and Retrofitting ITE, Westinghouse, Siemens-Allis, ABB, Federal Pacific, Cutler-Hammer and GE Circuit Breakers
Electric Control’s founder, Ed Kahn, went into business as an electric control equipment company, and his company still stocks the first generation of industrial circuit breakers. He supported all of those companies that could no longer get parts or complete circuit breakers. Rubber companies, airplane manufacturers, gas companies, utilities, universities, sewage plants and any buildings that employed more than 300 people most likely had circuit breakers in need of older parts.
In the 1960s, the era of planned obsolescence, the circuit breakers looked the same, but were not interchangeable as the prior generation of breakers had been.
Circuit Breakers with Solid State Trip Units
The 1970s saw the beginning of the solid state era, as diode transistors began to play a larger role in the industry as well as our everyday lives. Circuit breakers, though in functionality basically the same, now had solid state trip units. These new trip units would monitor the amperage on a given circuit far more accurately than their predecessors, and they lasted longer and required less maintenance. But these circuit breakers were still not interchangeable with any breaker made before this time.
Two-Year Warranty on All ITE, Westinghouse, Siemens-Allis, ABB, Federal Pacific, Cutler-Hammer and GE Circuit Breakers
In the 1990s, there was more refinement of the tripping mechanism. Any building built prior to this period had obsolete equipment and new parts from the original manufacturers were unavailable.
Contrast these previous years to the present: Today, I can sit with the head of maintenance at Logan Airport as he closes and trips all his circuit breakers from his PC. He can monitor each circuit breaker in his grid and print out peak running times. In other words, the evolution of that original 600V circuit breaker has come to the point that his equipment now talks back to him and records data from a central terminal.