1ZSC000562-AAX en, Rev. 1
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Technical guide VUC
9
Tap selectors
Although the tap selectors for the VUC range of tap-changer
are available in various sizes, all of them have similar functions
with different ratings.
The fixed contacts are mounted around the central shafts.
The moving contacts are mounted on, and are operated by,
the shafts in the center of the selector. The moving contacts
are connected, via current collectors, to the diverter switch by
means of paper insulated copper conductors.
Depending on the load current, the moving contacts have
either one or more contact arms in parallel with one, two, four
or eight contact fingers each. The fingers make contact at one
end with the fixed contact, and at the other with the current
collector. The moving contacts slide on the fixed contacts and
the current collector rings, giving a wiping action which makes
the contacts self cleaning. This arrangement promotes good
conductivity and negligible contact wear.
Fig. 4. Tap selectors: size C, size III and size F.
The tap selectors available for the VUC range of tap-changers
are C, III and F. Tap selector C can be combined with VUCG
diverter switches. Tap selectors III and F can be combined
with both VUCG and VUCL. All tap selector types use a
complete, un-divided glass fiber reinforced epoxy cylinder for
the fine selector.
The change-over selector contacts are all made of silver for
high long-time stability and resistance against fretting.
