ELECTRICAL BREAKER

1. Turn off Caps Lock. Many readers consider capitals use to be akin to SHOUTING, and very rude.
2. Open-up an on-line encyclopaedia, such as Wikipedia
3. Enter 'Air circuit breaker' into the search box
4. Read the article.

OK, I'll take the challenge. 100 words or less... (not counting these)

Stationary contact and a movable contact, held together by a spring mechanism so that current flows with minimal resistance. When trip circuit is activated, either by the thermal effect of excessive current over a long time or the over-excitement of a magnetic plunger by instantaneous current surge, spring mechanism is released, forcing contacts open at high speed. When distance between the contacts increases to the point where dielectric strength of the air separating them is sufficient to extinguish the arc, the current stops flowing.

Modern breakers use electronics to sense the current now, but the rest is the same.

And yes... stop typing with the caps-lock key on. It makes you look lazy and inconsiderate of the readers. Humans read not only by letter but also by the shapes of whole words. Using the all caps forces the reader's brain to slow down and evaluate each letter one-by-one. That makes me want to ignore those posts.