skin effect
- Thread starter sivaji
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pierre
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- Westchester County, New York
Re: skin effect
High frequency events, such as lightning, cause the electrons (current) to flow mostly on the surface of a conductor (skin effect).
High frequency events, such as lightning, cause the electrons (current) to flow mostly on the surface of a conductor (skin effect).
Re: skin effect
Skin effect actually relates to eddy currents. Eddy currents are small pockets of misaligned molecules that occur in an AC-carrying conductor as the result of the rapidly-changing magnetic fields. These little rogue currents amount to a cumulative opposition to current flow, over and above the intrinsic resistance of the conductor material itself.
Eddy currents are greater toward the center of the conductor, having the effect of forcing current-carrying electrons outward, toward the surface. This is skin effect. That is why a stranded conductor, with greater surface area per unit volume, is more efficient at transferring current. (More skin!)
Since eddy currents are caused by the fluctuation of the magnetic field, you can imagine why their magnitude is in direct proportion to the frequency of the AC. And they only become pronounced at higher frequencies. In fact, our standard system of 60Hz AC is considered too slow for it to be necessary to account for eddy currents/skin effect in our impedance calculations (for stranded conductors).
Hope this helps.
-Tim Brain, Trainee.
[ October 15, 2005, 03:20 AM: Message edited by: TimWA ]
Skin effect actually relates to eddy currents. Eddy currents are small pockets of misaligned molecules that occur in an AC-carrying conductor as the result of the rapidly-changing magnetic fields. These little rogue currents amount to a cumulative opposition to current flow, over and above the intrinsic resistance of the conductor material itself.
Eddy currents are greater toward the center of the conductor, having the effect of forcing current-carrying electrons outward, toward the surface. This is skin effect. That is why a stranded conductor, with greater surface area per unit volume, is more efficient at transferring current. (More skin!)
Since eddy currents are caused by the fluctuation of the magnetic field, you can imagine why their magnitude is in direct proportion to the frequency of the AC. And they only become pronounced at higher frequencies. In fact, our standard system of 60Hz AC is considered too slow for it to be necessary to account for eddy currents/skin effect in our impedance calculations (for stranded conductors).
Hope this helps.
-Tim Brain, Trainee.
[ October 15, 2005, 03:20 AM: Message edited by: TimWA ]
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: skin effect
If a load is non-linear, then it will generate harmonics. This can be seen as a set of high frequencies that are present in the line. In one sense, harmonics are high frequencies.
No it can't. And it's not the other way around either.
If a load is non-linear, then it will generate harmonics. This can be seen as a set of high frequencies that are present in the line. In one sense, harmonics are high frequencies.
- Location
- Wisconsin
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- PE (Retired) - Power Systems
Re: skin effect
Prximity effect taken from General Cable:
"The proximity effect also increases the effective resistance and is associated with the magnetic fields of two conductors which are close together. If each carries a current in the same direction, the halves of the conductors in close proximity are cut by more magnetic flux than the remote halves. Consequently the current distribution is not even throughout the cross-section, a greater proportion being carried by the remote halves. If the currents are in opposite directions, the halves in close proximity will carry the greater density of current."
Prximity effect taken from General Cable:
"The proximity effect also increases the effective resistance and is associated with the magnetic fields of two conductors which are close together. If each carries a current in the same direction, the halves of the conductors in close proximity are cut by more magnetic flux than the remote halves. Consequently the current distribution is not even throughout the cross-section, a greater proportion being carried by the remote halves. If the currents are in opposite directions, the halves in close proximity will carry the greater density of current."
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