(57) A feedthrough insulator (10) for electrical transformers, comprising an insulating
body (18), which includes an outer portion (14), to be arranged in air, coupled with
an inner portion (15) in the electrical transformer tank, in which the outer and inner
insulating portions (14, 15) are crossed axially by a metallic tie rod (11), which
acts as an electrical conductor. In particular, the outer insulating portion (14)
has a series of fins (17), positioned close together and suitably sized, in order
to obtain high dielectric characteristics; moreover, at least one part of the entire
insulating body (18) has a combined insulating coating, formed from the coupling of
a layer of silicon, covering the underlying epoxy resin, which, in turn, surrounds
the electrical conductor (11). Inside the epoxy resin a metallic screen (19) is also
embedded, provided with arms (20), which has the dual purpose of screening the metallic
attachment components and the support base (21), for example on the tank of the transformer,
and of being used as condenser for the capacitive intakes, consisting of the aforementioned
arms (20).
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