skin effect

[hamid2001.]

hello,
i am a first year electrical engenering student. In a school project i try to mesure the skin effect in a wire using à daq my plan is to get both wave forms of voltage and current then i can easely calculate the resistance using my python code as :

R = impedance* cos(phase_shift)

its seems simple but the problem that i had is after trying with multiple wire i had never been able to get a sinusoide ( i got like a periodique form but deformed) . I also tryed to filtrate but i was loosing a lot of precision . maybe my next plan will be to use a wattmeter to get the phase shift but after asking professors there is no wattmeter in our school. Can u please provide me with some suggestion to be able able like to get a sinusoide.

Best regards, .

 

[waross]

mesure the skin effect
A different approach;
Do you have a signal generator?
Measure the impedance change of your sample at different applied frequencies.
Be aware that skin effect may also be influenced by wave shape.
Skin effect is also affected by current.
You may be able to demonstrate this by using different wave forms, rising saw tooth, falling saw tooth, sine wave.
You may be able to vary the current at given frequencies.
You may not have the equipment to pursue all of these approaches, but I am sure that you will find enough equipment to demonstrate some of them.
Note: Current dependency, as you vary the frequency be aware that if the current is not held constant, you may be looking at the combined effect of higher frequency and lower current.
Extra credit:
Try sending a frequency spectrum down you sample. See if a scope will show greater attenuation of higher frequencies.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[bacon4life]

hamid-This thread will likely disappear since student posting is not allowed per

https://www.eng-tips.com/market.cfm.

waross- My understanding was that the increase in resistance from skin effect was independent of current magnitude. Calculators such as

https://voltage-disturbance.com/engineering-calculators/skin-effect-calculator/

do not include a place to enter current magnitude. Perhaps you are thinking of variable resistance in single layer ACSR conductors, where the hysteresis losses in the steel core depended on the current magnitude? I had pictured ACSR as an iron core inductor, but I have never really thought through skin effect in a ferrous material.

 

[che12345]

My understanding on Skin effect the magnitude and importance of the effect increases with the frequency, the size, shape and thickness of the conductor. It is INDEPENDENT of the magnitude of the CURRENT FLOWING.
Che Kuan Yau (Singapore)

 

[waross]

I stand corrected. Please disregard my references to current.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[FacEngrPE]

This presentation of skin effect might help. This is for round conductors (solid bar and possibly pipe), The link does not provide source for the formula, you can use it as a hypothesis to be validated in your experiment.

https://www.electricaltechnology.org/2022/10/skin-effect.html[/URL]]Skin effect increases with an increase in frequency. If the frequency is very high, the charge distribution or the current density stays maximum at the very surface and forms a thin layer while the current density at the inner cross-sectional area or the core remains zero.

Skin effects maintain the current flow between the outer surface and a fixed depth from the surface called skin depth, δ. The skin depth varies inversely with frequency.

The skin depth can be calculated using the following formula.

Skin Depth = δ = 7.6 ÷ √ (f) … (cm)

And try this search link

https://duckduckgo.com/?q=skin+effect+in+transmission+line&t=lm&ia=web