When I was a kid I always wondered why Dr. Sattler had to manually prime/charge the breaker before enabling it. Apparently it is because that model (and others like it) use a spring to quickly close the circuit. When she is priming it puts tension into the spring, and when she presses the button it quickly releases and completes the circuit. This is done to prevent arc flashes due to the high voltage and amperage, since the coiled spring snapping into place can complete the circuit much faster than any human pulling a lever could.

> it puts tension into the spring

Well it certainly put tension into the scene! Thanks.