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.
"Ted Samuels" wrote in message
...
William Noble wrote:
top posted again to annoy everyone.
1. 6 hz is almost DC - I am quite positive that the variac is not 6 hz -
if so, it
would weigh an amazing amount - something else is wrong.
I was wrong about the 6HZ but not by much. I assumed that I was in error
when I read
350 CPM and wrote 360 CPM but it was in fact 350 CPM (5.83 HZ)
2. a 400 hz variac powered at 60 hz won't blow a breaker immediately, but
it will
overheat rapidly (a vew seconds to smoke starts)
I would speculate that you wired it incorrectly - did you try looking up
the specific variac on the superior electric (I think that's right) web
site? can you
explain exactly how you wired it? does it trip the breaker if you
disconnect the
bridge?
As I mentioned to Don : this unit carries the registered Variac(R)
trademark but was not made by superior, it was made by Technipower
of Davis instruments and calibration, type M 10, CDC part number
23253800.
Not at all in doubt about wiring as I removed that Variac and replaced it
with another and it's working just fine. The only question I have is that
the motor I am running is rated as 60 volts at 11.2 amps and the Variac is
rated as 120 Volt at 6.0 amps.
I would assume I'm OK with a 672 watt load through a 720 watt transformer
but maybe there is something I am missing.
I ran continuously (no load) for 15 min and found no heating of the
Variac the bridge rectifier or the motor.
T
--
Posted via a free Usenet account from
http://www.teranews.com