Re: saturable reactor vs choke

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

Hi Gerry, David,

I believe a saturable reactor works much the same no matter if the 
"knee" of the magnetic material is "hard" or "soft", but hard is 
preferable. As far as I know, a saturable reactor works as a phase 
angle controlled switch just like a lamp dimmer, and the control coil 
bias determines the point in each half-cycle where it flips from 
unsaturated to saturated.

I've seen ferrites for HF saturable reactors in a Fair-Rite catalog 
and they seem to be designed with a vey hard knee. And a warning not 
to operate too near their acoustic resonance frequency in case they shatter :-/

Steve Conner
http://www.scopeboy.com

At 20:56 14/04/06 -0600, you wrote:
> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Gerry,
>
> I'm not too sure of exactly what your asking but I'm assuming that 
> you are making referance to the "bell
> curve" or "J curve", actually, that would represent the magnetic 
> saturation range of the reactor's core on an x-y graphic? From what 
> little personal experience that I've had with SRs, by gradually 
> increasing the input DC voltage (usually something like 0 - 90 VDC 
> at a few amps), you will proportionately increase the allowed 
> current flow to the source load through the main coil. I BELIEVE 
> once full saturation is achieved (90 VDC input to the control 
> winding) then the main coil behaves almost like a short circuit. 
> Conversely, with a zero volt DC input to the control coil, the main 
> work coil will have maxi-
> mum inductance and L reactance to the main AC volt-
> age and will allow a relatively small current flow, irreagardless
> of the load, even if it's a short circuit.
>
> David
>
>
> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Friday, April 14, 2006 1:44 PM
> Subject: Re: saturable reactor vs choke
>
>
> > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> > Hi David,
> > A few questions:
> > If one has a saturable reactor and the BH curve is sorta ideal with 
> > respect to the knee ( ie: it has constant slope until it saturates 
> > and then the curve precisely flattens out), I'm wondering what 
> > happens when this knee is reached.
> > Does the current scream very high or is there a smooth transition 
> > to larger current as the saturation point is changed??
> > Does a saturable reactor require a soft knee??
> > Gerry R.
> >
> > > Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
> > >
> > > With a "saturable reactor" (SR), in addtion to the "working"
> > > inductive coil, there is also a "control coil" of usually many
> > > more turns of smaller guage wire than the main "working"
> > > coil. A relatively low, variable DC voltage is introduced into the 
> > > control coil to control the magnetic saturation of the iron
> > > core so as to control the current flow through the main
> > > working coil. This allows infinite range of the current that's
> > > allowed to flow through the main working coil, irregardless
> > > of the source load.
> > >
> > > David Rieben