transformer expertise needed IE: saturation

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

HV,
Please respond if x-posting annoying you.

Hi Aaron, all
-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Thursday, March 09, 2006 5:49 AM
To: tesla@xxxxxxxxxx
Subject: Re: Three phase transformer arrived for saturation experimentation.

Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

There shouldn't be any AC in the center windings if
the outer windings are connected properly.  However it
*does* seem as though saturation ought to be more
easily achieved using the outer two HV windings for
the control rather than the inner HV winding.  The
legs of a three-phase transformer all have the same
cross-sectional area.  That suggests that saturating
the center leg will not translate into saturation of
the outer legs.

********* Good point, however, this does not take into account the energies
exerted on these cores. And I don't suspect it would be proportional. I
can't speak to what happens to a core when pure DC is subjected to it, but
some variables are clear. The polarity is steady state so the field is
constant and likely greater than .707*60,hmm that brings up the point that
one 1/2 cycle is phased , one is not. Brute force has to win this I suppose.
How much that trumps the DC field concentration fully escapes me. So
seemingly, I agree option 2 is a better choice forgoing the currents carried
by the single target winging which, at full, saturation should be
adequate?******

However, by applying a suitable
current to the outer HV windings (wired so as to aid
each other), it seems one ought to be able to
completely saturate the outer legs quite easily.  On
hvlist, however, it was mentioned that complete
saturation by the control alone is generally not
required when the power winding is passing current, so
considering saturation from the point of the control
may not be completely valid.  I'd love to see it tried
both ways, if possible.

40 ohms on the 5kV windings sounds like goodness to
me!

Regards,
Aaron, N7OE

--- Tesla list <tesla@xxxxxxxxxx> wrote:

 > Original poster: Steve Conner <steve@xxxxxxxxxxxx>
 >
 > Hi Jim, all,
 >
 > A few thoughts on using a three phase transformer as
 > a saturable reactor.
 >
 > I don't think you can use the centre limb as the
 > control winding,
 > because having only a single winding, you can't
 > cancel the induced
 > AC. I think the only hook-up that will do anything
 > is to use the 208V
 > winding on the centre leg in series with the load,
 > and the HV
 > windings on the two outer legs as the control
 > windings.
 >
 > As for how much control current will be needed: I
 > think amp-turns are
 > conserved. So if you pass 1 amp through each of the
 > 5kV HV windings
 > in series, it would try to deliver about
 > 1A*(5000*2/208)= 48A to the
 > load, and since the rated HV output current is 1A,
 > that would be a
 > reasonable maximum rating for the thing as a
 > saturable reactor.
 >
 > Steve Conner
 > http://www.scopeboy.com/
 >
 >
 >