Citadel 2.0 - Instruction Manual - page:
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V A C U U M I N T E R R U P T E R / O P E R A T O R
Vacuum interrupters
The vacuum interrupter is a simple device with two internal electrical power conducting contacts.
One is secured in place and stationary within the vacuum interrupter assembly. The other contact
can move a short distance in and out (approx. 1/2”) to electrically make-up or separate the
contacts.
A metal bellows (accordion assembly) is welded around the moving contact structure.
This permits contact movement while maintaining vacuum inside the interrupter.
The movable contact is connected to the driving mechanism of the circuit breaker via electrically
insulated push rod assemblies.
When the two contacts separate inside a vacuum, an arc is initiated that jumps across the
contacts and continues conduction up to the next point that the AC current goes through a zero
crossing. At this “current zero” crossing the arc extinguishes.
Any metal vapor that has formed by the arcing will now condense back onto the contacts and on
the surrounding arc shield.
FIXED CONTACT
CURRENT CONNECTION
MOVING CONTACT
METAL BELLOWS
FIXED CONTACT
CERAMIC INSULATOR
CERAMIC INSULATOR
GUIDE
MOVING CONTACT
CURRENT CONNECTION
ARC SHIELD
DRAWING 5