ETL 1110-2-533
30 Sep 94
Figure B-30. Individually supported cooler ele-
ments. Each cooler element has its own trans-
former case penetration which also serves to
Figure B-28. Cooler elements mounted to a mani-
support the cooler. Flange leaks have not been
fold. Individual cooler sections are mounted to a
observed for this type of configuration. The end of
manifold which is connected to a flange forming
the coolers which is most distant from the trans-
the transformer case penetration. The cooler does
former body is also restrained by a small angle
have a vertical support and a small diagonal brace.
iron brace
Lateral motion exerts large moments on the flange
causing oil leaks. A simple modification is to add
angle iron brace between the outside end of the
(q) It is relatively easy to add lateral and vertical
manifold and the corner of the transformer case
braces; however, it is important that they are both
strong and rigid. These braces should be provided at
both the bottom and the top of the coolers. Vertical
braces must reduce the load on the upper transformer
case penetration; thus, they must be connected
between the transformer case and coolers and/or the
manifold.
(r) Some transformers are designed with substan-
tial cooler supports, and the piping connection to the
transformer case penetration is relatively flexible
(Figure B-31).
(s) Transformer-mounted surge arrestors fre-
quently fail. In general, when this occurs they can be
removed from the system and replaced later when
spare parts and time are available. A more serious
concern about the failure of the surge arrestor is that
Figure B-29. Bracing of lower cooler manifold. A
it can damage a transformer bushing when it falls
diagonal angle iron serves as a brace between the
after it fails. The configuration of the bus connection
transformer body and the cooler manifold. Note
between the surge arrestor and the bushing usually
that the connection to the manifold is through an
controls this interaction.
angle. While this may be strong, it is very flexible
so that the cooler assembly is not adequately
(t) Oil leaks at bushings and, less frequently,
restrained, and large moments can be applied to
bushing failures can put a transformer out of service.
the flange on the transformer case penetration
At this time there is no effective remedy for this,
B-18
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