RE: Saturable Reactor

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>

Did you measure the current in the pig at max power?

thanks
Adam

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

> Original poster: "Carl Litton"
> <Carl_Litton@xxxxxxxxxx>
>
> We would love to see someone produce an SR using a
> couple of small pole
> pig (or mini-pig) transformers as suggested below!
>
> We were also able to complete our series of tests on
> the MOT type
> reactor this past weekend.
>
> The previously reported series pair reactor was
> scaled up to 4 pairs of
> MOT's each wired in this manner.  We did not have 8
> absolutely identical
> MOT's so we knew there would be some voltage
> developed in the control
> winding with such a large and varied configuration.
> Several connection
> schemes were tried in the attempt to produce the
> most suitable
> inductance range while limiting the voltage in the
> control to the
> minimum.  The optimum arrangement with the
> particular transformers we
> used turned out to be to construct two quads in
> which all 4 units of
> each were placed in series aiding with each other on
> the primary side
> and then to connect the two quads to the test
> circuit in parallel.  As
> before, all of the secondaries forming the control
> were wired in series
> opposing between pairs of MOT's and the pairs then
> wired together in one
> continuous series.  The result was about 50 Volts in
> the control when
> the reactor was placed in a 240 VAC circuit.
> Approximate schematic
> here:
>
> http://hvgroup.dawntreader.net/8motschematic240v2
>
> As a sort of 'acid test,' we chose to ballast a 10
> kVA pole pig with the
> reactor.
>
> http://hvgroup.dawntreader.net/reactoronpig.jpg
>
> http://hvgroup.dawntreader.net/reactorandcontrol.jpg
>
>
> With no DC in the control, there was produced only a
> tiny hissing spark
> between the uprights of Jacob's Ladder attached to
> the pig, indicating a
> high reactance and very low current.
>
> http://hvgroup.dawntreader.net/nocontrolvoltage.jpg
>
> Introduction of 20 to 30 VDC into the control
> resulted in the widening
> and lengthening of the arc that then began to travel
> part way up the
> ladder.
>
> http://hvgroup.dawntreader.net/lowcontrolvoltage.jpg
>
> Increasing the voltage in the control winding to its
> full value of about
> 140 VDC caused the ladder to spring to life in its
> familiar form - a hot
> billowy plasma arc that traveled the full length of
> the ladder.
> Increasing the control voltage to 525 VDC produced
> no noticeable change
>
>
http://hvgroup.dawntreader.net/fullcontrolvoltage.jpg
>    (little blurry
> but recognizable)
>
>
> After allowing the ladder to run for several minutes
> with the reactor
> wide open in its maximally saturated state and
> therefore with maximum
> current in the test circuit, all power was cut to
> the circuit and the
> reactor inspected for problems.  Amazingly, there
> was no detectable heat
> in any of the transformers.  This is considered a
> very successful test
> of this configuration..
>
> Our thanks to Aaron and all others on both lists who
> contributed helpful
> suggestions and comments to this and related threads
> regarding this
> interesting concept.
>
>
> Carl Litton
> Memphis High Voltage Group
>
>
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Sunday, March 05, 2006 7:32 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: Saturable Reactor
>
> Original poster: "J. Aaron Holmes"
> <jaholmes@xxxxxxxxxxxxxxxxxx>
>
> MOTs seemed ideal because they're cheap, relatively
> HV, and available.  The problem with common 240/480
> three-phase transformers is that the windings are
> going to have very low DC resistance, owing to
> heavy-gauge windings and relatively few turns in
> those
> windings.  These characteristics will mean that your
> DC control will have to put out quite a bit of
> current
> at a very low voltage, which is a little awkward.
>
> I tried to locate a three-phase transformer having a
> high voltage of 2400-4160V, which would tend to
> imply
> a higher DC resistance on the HV winding, and
> therefore a better chance of using one or more of
> the
> HV windings for a control winding by simply hooking
> up
> a recitified variac.  I did immediately locate a
> 3kVA
> 4160V-240V transformer on eBay, but the guy wanted
> almost $500 for it!  By contrast, my local utility
> offered me a 75kVA three-phase unit,
> 14.7kV-480/277V,
> for $300 (they're nice to me :))  It was oil-filled
> and weighed several tons.  Had to turn that one
> down,
> though! (maybe someday I'll have the real estate to
> play with something like that).
>
> ...but there's nothing magical about the MOT idea.
> Pairs of identical pole transformers ought to work
> nicely, too.  When talking about stuff like that,
> however, I start to get pretty worried about what
> might happen if one pig should fail.  In fact, even
> with MOTs, I'd like to see some more research done
> into how to make the MOT-based SR's safe.  Not
> pushing
> them too hard certainly seems like a good idea!!
>
> Regards,
> Aaron, N7OE
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
>   > Original poster: Yurtle Turtle
> <yurtle_t@xxxxxxxxx>
>   >
>   > Most recent talk about SR's has been on MOT's,
> but I
>   > seem to remember someone mentioning a 3 ph. dry
> type
>   > distribution transformer, such as this one:
>   >
>   >
>
http://www.hot-streamer.com/adam/garage/transformer_30a_kVA.jpg
>   >
>   >
>
http://www.hot-streamer.com/adam/garage/transformer_30b_kVA.jpg
>   >
>   > Has any further work been done for something
> like
>   > this?
>   >
>   > thanks
>   > Adam
>   >
>   >
>   >
>
>
>