Re: Variac Faults

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

yup, they can burn.

One common way the get a few cripsy turns is the knob never get operated and
they sit at one setting forever. The brushes loosen up or the plating on the
coil oxidizes and the crud never gets rubbed away, and resistance goes up
and then it gets hot.

You can easily spot this though by burned looking turns wherever the brush
was parked. I've seen lots of junk like this on the surplus market. There is
no reason you cannot clean the coil surfaces and burnish them clean again if
it's not burned too bad.

KEN


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 01, 2002 7:21 PM
Subject: Variac Faults


 > Original poster: "Matthew Smith by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <matt-at-kbc-dot-net.au>
 >
 > Hi All
 >
 > When buying second-hand Variacs, what are the things that are likely to be
 > wrong with them?  I would imagine that brushes may be worn/broken, but has
 > anyone seen one actually burnt out before?
 >
 > I've just bid on a 25A 300V (240V in) beauty and was wondering just how
far
 > to go...
 >
 > Cheers
 >
 > M
 >
 > --
 > Matthew Smith            | Business: http://www.kbc-dot-net.au
 > IT Consultant            | PGP Key:  http://gpg.mss.cx
 > Kadina, South Australia  | * Tivis Project * Community Connect *
 >
 >
 >
 >
 >