Induction Stove for Hysteresis Experiments...

Hi everyone,

I'm trying to use a commercially available induction stove used for
cooking to determine the hysteresis losses (power losses)in magnetic
structures when exposed to AC fields - I hear these stoves provide
frequencies in the 20-35 kHz range - however, I'm not really sure about
the field strengths of them (I've been using a coil of wire fed into a
scope to determine the relative magnitude of the field and frequency.)

Typically these stoves set up mostly eddy currents, but also create
hysteresis losses in large iron or stainless steel pots (they only
activate if they sense a magnetic material on it.)

I'd like to work with them and avoid building a very large induction
heater which will cost a lot and have to be water cooled because of the
current that they draw.

Any suggestions or advice would be really helpful!

Thanks.

Kyle

 

You may be going about this a little bass-ackward.

Firstly, hysterisis is a material characteristic that would have to be
measured, applying a controlled field. These materials are available
in structures that make this fairly easy.

Then the losses resulting in the hysterisis measurement setup have to
be measured. Calorimetric methods are the least equipment-intensive.

Heating through externally applied magnetic field is crude and
uncontrollable.

RL

 

Heating through externally applied magnetic field is crude and

Many years ago, it was a classic way to heat steel for things
like, well, heat treating. Pick the frequency for the depth of
heating.

Is there a modern replacement that's better?

 

Absolutely!
Collect a good quantity of Elephant or Rhino poop and make a fire for
heating.
....sorry; you are not in the Africa flatlands...

 

I read in sci.electronics.design that Robert Baer
..pas.earthlink.net>) about 'Induction Stove for Hysteresis
Experiments...', on Mon, 28 Feb 2005:

Even if he were, it would take ages to collect a 'good quantity of rhino
poop'. Very few rhinos left. (8-(

 

Perhaps a CO2 laser with an excitation depth of few um ?
The surface picks the heat very quickly and some percentage
is reflected from the boiling metal in whatever direction
making it necessary to cover the whole process.
For some applications perhaps.

Rene

 

To the contrary actually.
The field geometry of the coil is known. The resonating coil
draws as much current as it can dump into the material.
At least to me it appears as controllable as a gaz torch.

Rene

 

How about hippo poop...... ah, but they shit in the bath so you might spend
a long time waiting for it to dry out.

DNA

 

This fellow is looking to measure the effect - heating,
due to a cause - hysterisis, under the influence of a measurable
alternating magnetic field in the material.

"Measuring Soft Ferrite Core Properties"
http://www.tscinternational.com/tech4.pdf

"Testing Critical Characteristics of Soft Ferrite Materials
for Power Applications"
http://www.tscinternational.com/tech7.doc

"Ferrite Property Measurement"
http://www.steward.com/pdfs/cores/ferrprop.pdf

As one is dependant on the other and temperature, being characteristic
material properties, they all have to be measurable (and controlable
to a certain degree) before meaningful results can be extracted.

In some cases, a simple substitution of material, with all other
factors fixed, will tell you all you practically need to know, as the
material is seldom otherwise a candidate for user-controlled
'variation'.

RL

 

And even collecting elephant poop, you'd have to compete with the scarabs.

Cheers!
Rich

 

You mean it can be estimated.

Might as well estimate the whole shebang, which probably makes the
most sense if you really want to avoid the tedium of making calibrated
measurements and can only alter the hystertic properties in question
by buying something else, any road.

RL