How do vacuum circuit breakers operate in an industrial plant?

Here is a diagram for a VCB:

Vacuum Circuit Breaker (http://www.sayedsaad.com/substation/circuit_breker/cb5.htm)

If your question refers to the word "vacuum", each contact is enclosed in a sealed vessel, sometimes called a "bottle". This enclosure contains the arc from normal opening operations and they will contain and extinguish the arc blast from a short circuit fault.