Re: Higher Mains Frequency

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

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

Doe anybody know off hand if older "international series" open frame linear
power supplies from Power-One, Condor and all the other clones of each other
companies in California USED to be rated 40-440Hz or something like that?
Apparently, the only ones I have left are made in the late 90s and are
probably from Mexico, and rated 47-63Hz. It would be interesting to compare
transformers if this was the case.

KEN

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, June 19, 2003 10:34 PM
Subject: RE: Higher Mains Frequency


 > Original poster: "Black Moon by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<black_moons-at-hotmail-dot-com>
 >
 > Very intresting... I thought at 400hz there would be much less inductive
 > current and therefor not to much eddy current but I guess I was wrong
 >
 >
 >
 > >Not necessarily.  60Hz transformers are not a drop in replacement for
400Hz.
 > >During my days of designing avionics for aircraft, I built many a test
 > >fixture for 400Hz operation.  Most of the avionics I worked on were
 > >illuminated panel type stuff, so there was lots of power at 400Hz
required
 > >to light tons of incandescent lights (LEDs on newer aircraft and
retrofits).
 > >Numerous times i attempted to use standard 60Hz power transformers in
these
 > >test fixtures to provide different
 > >voltage levels I needed etc..., but almost always, they did not work
 > >properly.  The cores just get way too hot to the point
 > >where they burn the enamel right off the windings.  We always had to
order
 > >special 400Hz transformers which used a different core material.  I'm not
 > >sure how MOTs would stand up to 400Hz though.
 > >
 > >So, 60Hz transformerse are not a drop-in replacement for 400Hz.
 > >
 > > > Well, you don't need inverters for one.
 > > > 2nd, your 60hz transformers will probley still work on it,
 > > > and all smps
 > > > would, mabey with poor power factor but a simple modification
 > > > could help
 > > > fix that.
 > > > 3rd, less idle current for transformers, smaller transformers
 > > > for the same
 > > > power.
 > > >
 > > >
 > > >
 > > >
 > > > > >The concept indeed looks interesting, but why change an
 > > > already perfectly
 > > > > >working system!!!  60Hz is more than readily available -
 > > > why add the
 > > > > >complexities of a multi-kilowatt inverter system.
 > > > >
 > > > >Because it's fun darnit! And educational too. People
 > > > probably said the same
 > > > >about the SSTC when it was first invented.
 > > > >
 > > > >Anyway, personally I have two thoughts on this.
 > > > >
 > > > >1) By driving a transformer at a higher frequency you can
 > > > get more voltage
 > > > >before it saturates. Ferinstance an MOT at 400Hz could give
 > > > 12kV and (more
 > > > >importantly) one of those little 12v:240V transformers would
 > > > give 1600V.
 > > > >Also they have chambered plastic bobbins that give good
 > > > primary/secondary
 > > > >isolation.
 > > > >
 > > > >One could imagine an 'MMT' made of about a dozen of these little
 > > > >transformers in series, maybe in oil, with the 12V primaries
 > > > all in parallel
 > > > >driven off a half-bridge inverter that runs off the
 > > > rectified 120V line. An
 > > > >HVDC supply would be equally easy to make by just putting a
 > > > small bridge
 > > > >rectifier and cap on each transformer and stacking them in series.
 > > > >
 > > > >2) You can get 115V 400Hz three-phase generators cheap from military
 > > > >surplus. They come in ridiculous powers all the way up to
 > > > 60kW gas turbine
 > > > >powered units. Imagine a 12-MOT bank running off one of those.
 > > > >
 > > > >Steve C.
 > > > >
 > > >
 >
 >
 >