Skin Effect
- Thread starter Basra123
- Start date
- Status
bphgravity
Senior Member
- Location
- Florida
More skin...
zog
Senior Member
- Location
- Charlotte, NC
Ha! More skin, well put. ( that is a scary pic of T.E.)
1793
Senior Member
- Location
- Louisville, Kentucky
- Occupation
- Inspector
At one of Thomas Edison's Birthday parties, my grandfather had the great pleasure of meeting him.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Skin effect is a function of frequency and "depth" of conductor.
At 60Hz skin effect is not a factor until 266kCMIL.
At 60Hz skin effect is not a factor until 266kCMIL.
pierre
Senior Member
- Location
- Westchester County, New York
What about lightning or transients on smaller conductors?
Skin effect is an phenomena that occurs when an A/C voltage is applied to a conductor. The effect causes the electron flow to move toward the outside area of the conductor. The higher the frequency the greater the effect. If you could look at cross section of a #12 conductor the electrons have move toward the outer surface but there is only so much room for the movement. There are some electrons still left in the center most part of the conductor. The larger conductor have a much larger area for the electron movement so most will be able to vacate the center most part of the conductor. As the area vacated in the center gets larger the less copper is being used as a conductor. In theory you could remove some of the center strands without affecting the resistance of the conductor.
A measurement of this effect is given in the ratio of AC/DC resistance.
For conductors up to #1 the ratio is 1. For conductors in metallic conduit Beginning at #1 the ratio is 1.01 thru #3/0. From #4/0 the ratio begins to increase from 1.02 to 1.44 for #1000.
jtester
Senior Member
- Location
- Las Cruces N.M.
I've seen research work done on conductors that consisted of an outside layer of copper strands wound around what could be best described as a twisted I-beam. The I-beam twisted in one direction, one revolution every so often, and the outside layer of stranding was wrapped in the other. It was basically a hollow conductor.
This was research into transmission line design back in the 1930's, and obviously never caught on.
Jim T
This was research into transmission line design back in the 1930's, and obviously never caught on.
Jim T
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
At 60Hz skin effect is negligible for normal conductors smaller than 300kCMIL. For smaller conductors installed in conduit the "proximity effect" is much more of a factor.
In skin effect, the electrons are "forced" to the outside of the conductor. In proximity effect the conductors are forced away from the edge where two conductors are near each other (and in particular where they touch).
Proximity effect is similar to skin effect in that it causes an increase in AC resistance versus DC resistance. Many people incorrectly interpret the standard AC/DC resistance factor tables as being caused by skin effect only.
In skin effect, the electrons are "forced" to the outside of the conductor. In proximity effect the conductors are forced away from the edge where two conductors are near each other (and in particular where they touch).
Proximity effect is similar to skin effect in that it causes an increase in AC resistance versus DC resistance. Many people incorrectly interpret the standard AC/DC resistance factor tables as being caused by skin effect only.
- Status