Monitor xfmr

[Domenic M. Mallozzi]

In a message dated 98-07-02 02:44:22 EDT, you write:

<<      HEATH at LISTSERV.TEMPE.GOV >>
 Hi folks

I will throw my two cents into the "mode of failure in transformers"
discussion. I think its important to realize that high voltage transformers
are somewhat a strange situation. I think Murray did a good job of describing
most failure modes. One that is often missed is the total physical design of
the transformer.

Two things in the physical design come to mind:

1) Lead dress around sharp points (i.e.: the corners of a square core)

2) Case to conductor corona (in some cases this mode occurs when in
encapsulated transformers when the cases is made of different dielectrics and
they do not 'bond' properly, leaving voids that show up as corona points)

The only way to easy find these kind of problems is to do corona testing. It
is neither cheap nor easy. I spent a few years as a test engineer for a
military transformer manufacturer and corona testing was a black magic
activity that was passed on from old engineer to new engineer. How you setup
the test and perform it is an art as much as a science. As a result it is
typically only done in a hi-rel and military environment and is not often seen
in a commercial environment.

Well, so much for my turn on the soapbox.


Dom
N1DM

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