Click on the image to check the artwork
The adoption of vacuum technology for the switching of electrical currents was driven by the realization that a one-centimeter gap within an X-ray tube could sustain voltages in the tens of thousands. While early patents for vacuum switching devices emerged in the 19th century, these innovations did not immediately translate into commercial products. It wasn't until 1926 that a team led by Royal Sorensen at the California Institute of Technology conducted pioneering research into vacuum switching, experimenting with multiple devices and delving into the fundamental mechanisms of arc interruption in a vacuum environment. Sorensen shared his findings at an American Institute of Electrical Engineers (AIEE) conference that same year, forecasting the eventual commercial viability of vacuum switches.
Encouraged by these advancements, General Electric acquired the relevant patent rights in 1927 and embarked on the commercial development of vacuum switching technology. However, the onset of the Great Depression and the concurrent rise of oil-filled switchgear led to a reduction in development efforts, and significant progress in the commercialization of vacuum power switchgear was largely dormant until the 1950s.
A turning point came in 1956 when Hugh C. Ross of Jennings Radio Manufacturing Corporation introduced a revolutionary high-frequency-circuit vacuum switch capable of handling 15 kV at 200 A. Building on this foundation, Thomas H. Lee of General Electric unveiled the first vacuum circuit breakers in 1961, rated at 15 kV with short-circuit breaking capacities of 12.5 kA. By 1966, the technology had advanced to support devices with a rated voltage of 15 kV and short-circuit breaking currents of 25 and 31.5 kA.
Following the 1970s, vacuum switches began to supplant minimal-oil switches in medium-voltage switchgear, marking a significant shift in the industry. The early 1980s saw the gradual replacement of SF6 switches and breakers with vacuum technology in medium-voltage applications, further solidifying the position of vacuum interrupters in the market.
By 2018, the capabilities of vacuum circuit breakers had expanded to encompass voltages up to 145 kV and breaking currents as high as 200 kA, reflecting the continuous evolution and improvement of this technology.
A typical medium-voltage three-phase vacuum circuit breaker incorporates three vacuum interrupter housings, each designed to manage the electrical demands of a single phase. Vacuum interrupters can be categorized based on their enclosure type, application, and voltage class. Early experimental, radio-frequency, and power-switching vacuum interrupters featured glass enclosures, while contemporary models for power switchgear are constructed with ceramic envelopes, offering enhanced durability and performance.
These devices find application in a wide range of electrical systems, including circuit breakers, generator circuit breakers, load switches, motor contactors, and reclosers. Specialized vacuum interrupters are also manufactured for niche applications, such as transformer tap changers and electrical arc furnaces, underscoring the adaptability and broad utility of this technology in modern electrical engineering.
http://www.shonevac.com/