mbrooke
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Why does reactance vary with conductor temperature? What is the physics behind this? I always thought it held true only for resistance.
Reactance varying with temperature
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mbrooke
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winnie
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I am just guessing: You are looking at what appears to be 'aluminium clad steel' conductors. I figure that the magnetic steel alters the reactance, and that the permeability of the steel is changing with temperature.
-Jon
-Jon
mbrooke
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Thats probably it. Here is the PDF:
How would you define permeability?
winnie
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Magnetic permeability https://en.wikipedia.org/wiki/Permeability_(electromagnetism)
Basically in the presence of a magnetic field you get magnetic flux. The relationship between field and flux is the permeabililty.
Think about an inductor wound on a core. The permeability of the core is one of the factors that determines the inductance.
In the case of these cables, the steel in the wire is part of the region where the magnetic field passes, so the permeability of this steel affects the inductance of the wires, and temperature will change this.
-Jon
Basically in the presence of a magnetic field you get magnetic flux. The relationship between field and flux is the permeabililty.
Think about an inductor wound on a core. The permeability of the core is one of the factors that determines the inductance.
In the case of these cables, the steel in the wire is part of the region where the magnetic field passes, so the permeability of this steel affects the inductance of the wires, and temperature will change this.
-Jon
mbrooke
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Thanks- I will read up on this. I know a magnet's strength caries with temperature.
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And above the critical temperature for a particular ferromagnetic material that ferromagnetism vanishes.
drcampbell
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If ACSR distribution lines approach the critical temperature of steel, you have bigger problems than estimating reactance.
mbrooke
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gadfly56
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That's the Curie temperature. Yes, that Curie, the male half of the team, Pierre.
mbrooke
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Maria Curie?
gadfly56
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Yes, Marie and Pierre.
Carultch
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I thought the relationship between field and flux, was multiplying by area. Or more generally, the surface integrals that are used in Gauss's laws. And that permeability is the property of a magnetic material amplifying a magnetic field, from what it would be in empty space.
winnie
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Even though I work in electric motor design, I always have a problem relating the units.
I should have said field and _flux density_.
In free space the magnetic field is the same as the flux density.
Add a magnetic material and the flux density will be different than the field.
en.wikipedia.org
-Jon
I should have said field and _flux density_.
In free space the magnetic field is the same as the flux density.
Add a magnetic material and the flux density will be different than the field.
Magnetic field - Wikipedia
en.wikipedia.org
-Jon
Julius Right
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See for instance:
www.jstor.org
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