Re: saturable reactor vs choke

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi David,

The BH curve looks like the BI curve (since H and I are related).  B 
(y axis) and H (x axis). This is the curve with hysteresis and has a 
sloped region when H goes from negative to positive (B is still 
negative when H crosses 0) and another sloped region when H goes from 
positive to negative (B is still positive when H crosses 0 so doesnt 
follow the same path, hence the hysteresis).  as H gets too large, 
the B flattens out showing saturation.  I'm trying to contrast two 
materials, one where saturation occurs abruptly and another where the 
slope of the curve gradually flattens out (soft knee).  If the knee 
is abrupt does the current go to infinity when the saturation point 
is reached or do things still behave rationally.  Also, it seems like 
saturation aided by the DC current will occur in one AC direction 
only.  Not sure what the implications are.

Gerry R

> 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