RE: Higher Mains Frequency

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

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.
> > >
> >