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Hermetically sealed
transformer is a transformer design which has no conservator. Here the
dielectric insulating fluid in the transformer tank is completely sealed
and is in zero contact to the atmosphere. The design avoids air in the
transformer tank thereby avoiding sludging and oxidation of the
dielectric fluid.
Hermetically sealed transformers are totally maintenance free and are
particularly suited for use in exposed outdoor environments such as
moisture, salt or dust laden atmospheres. They are used extensively in
chemical plants, oil and gas terminals where poor accessibility makes
regular maintenance impracticable. Transformers immersed in synthetic
coolants are suitable for use indoors with adequate ventilation or near
to the load center where oil would not be considered environmentally
acceptable.
Normally these type of transformers are accommodated by devices that
measure heat related volume variations. Gas cushion is used to
compensate the volume variation due to heat. Normally the gas is
nitrogen. This gas is thermally uncoupled from the dielectric liquid. |
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