[R-390] Coming: Real In-rush Protection / Step Start

[Randy and Sherry Guttery]

On 3/29/2012 12:01 PM, Tisha Hayes wrote:
> Eventually this
> weakens the leads, attachment points and laminates until something breaks
> off or the laminates become loose and circulating currents go through the
> roof, burning up the transformer.
>
Which begs the question: Chuck - you mentioned that you're 
seeing quite a few power transformer failures lately - any 
idea how they are failing? I.e. opens - or going up in 
flames? Being sealed - might be hard to determine, then 
again - might be interesting to open a few up and see if 
failure mode can be determined...

If - as Tisha has noted - it might be simple mechanical 
fatigue - it might not be a bad idea to see if there is a 
way to head off disaster before it strikes.  I have a 390A 
transformer from a radio parted out back in Guam (1975?) 
which has run as a 28V supply 24/7 for almost 35 years - 
maybe I better re-think that use! (it's the only "spare" 
390A transformer I have).   I guess like a lot of people - I 
had the idea they were bloody near indestructible as long as 
protected from shorts...   Hmmmm...  something new to worry 
about.

best regards...

-- 
randy guttery

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