Michael A. Terrell wrote:
Ted Samuels wrote:
William Noble wrote:
well, I agree something is odd about the first variac, but without either
looking at it, or a bunch of photos or something I can't tell you what. I
can tell you that I had a variac with brass holders for carbon brushes (it
had two), and one carbon brush had broken or worn off so the brass holder
contacted the windings - this caused a significant increas in current and
heating (because some windings were shorted by the brass) - there may be an
effect like this. the 350Cycles per minute nomenclature suggests that it is
a duty cycle spec not an input power spec but that's speculation on my part.
I can tell you for sure that you will NOT see a transformer rated at 350CPM
for input power frequency, so either it isnt' a transformer, or the spec is
for some other attribute other than input power.

??????

Well the brush looks fine so I do not know what to say. If I had an ammeter shunt I
might dare see what current is flowing across the Variac windings.

Send me your address privately and I'll send you a close up front, side and top view
of it.

Simply replace the "." in my posted address and replace it with a "1"

T

Look at the windings. I have seen them so oxidized that the brush
couldn't make contact.


I think I figured out the problem. The actual wording on the front of the Variac is
"350 CYCLES Min" I took it to mean "350 CYCLES Minute" but what it probably means is
350 CYCLES Minimum.

In either case it's just not suitable for 60 Hz.

T