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From: "John Jardine"
Subject: Re: welding a transformer core
Date: Tue, 17 Dec 2002 17:59:57 -0000
References: <0ftL9.3650$yq.118956@news><firstname.lastname@example.org> <5em7RWAy6s$9EwzA@jmwa.demon.co.uk>
NNTP-Posting-Date: 17 Dec 2002 17:47:09 GMT
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John Woodgate wrote in message
> I read in sci.electronics.design that Gibbo
> wrote (in <email@example.com>) about 'welding
> a transformer core', on Mon, 16 Dec 2002:
> >No quotes as non are applicable.
> >Can someone please explain to me why someone would want to weld the
> >laminations of a transformer core (which are specifically made to have a
> >non-conductive surface) together and thereby dramatically increase core
> >What have I missed ?
> Welding the E and I lams together at the edges proves not to cause
> unacceptable losses. The welds have rather a small cross-section and a
> high resistivity. In fact, because the welds are made with the E and I
> blocks pressed tightly together, losses due to the air-gap are
> minimised. Performance is comparable with that achieved with interleaved
> core stacking, which is a time-consuming process, even when automated.
> Regards, John Woodgate, OOO - Own Opinions Only.
> Interested in professional sound reinforcement and distribution? Then go
> PLEASE do NOT copy news posts to me by E-MAIL!
Yes the extra losses are low. The circulating eddy currents in each thin lam
section are pretty much identical, as the magnetic field within the core is
'homogenous'. The welded 'short circuit' across the insulated lams is in
reality across eddy current generated 'potentials', that are all at the same
level so there is only a small disturbance of the existing eddy current
flow patterns. The weld 'bead' itself will develop circulating eddy currents
but these will be minor.
I'd go so far as to suggest that that a transformer with one whole side
welded solid could still be easily usable.
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