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A. The stationary
contacts and the multi-chamber rotor (an assembly of interlocking
parts which form a rotational framework including moving contacts)
are housed in a clear cylindrical shell. The stationary contacts
are supported independent of the cable entrance bushings,
eliminating possible misalignment resulting from tank deflections.
Tank deflections are caused by normal tank pressure variance
due to ambient temperature fluctuations. Each rotating contact
simultaneously disengages from two stationary contacts, providing
two break points per phase. This provides improved interrupting
capability as compared to single break contact systems.
B. As the
rotor tube assembly turns to disengage the moving contact from
the stationary contacts, dielectric media (SF6 gas) is compressed
between the impeller and stator. The shell, phase barrier and
rotor tube also act to confine the gas for proper compression
and flow. The compressed SF6 gas is directed through the nozzle
into the arc zone. The SF6 flows across the contacts and around
the arc established by the separating contacts, cooling the
arc over the length of the nozzle. The cooling action is increased
by the higher pressure (due to compression) and the flow of
gas which constantly provides a supply of cool SF6 into the
arc zone.
At current zero, the temperature of the
arc is reduced to the point of deionization. The SF6 gas rapidly
recovers dielectric strength withstanding the system recovery
voltage and preventing re-ignition of current across the contacts.
As the rotor tube assembly turns to
engage the moving contact with the stationary contacts, the
impeller induces a flow of SF6 gas between the contacts to
minimize prestrike.
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