Skin effect or total crossectional area

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Discussion Overview

The discussion revolves around the concept of skin effect in electrical conductors, particularly comparing solid and stranded wires, and its implications in various contexts, including liquid conductors. Participants explore the factors affecting ampacity and resistance in different scenarios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that stranded wire has a higher ampacity than solid wire due to increased surface area, potentially linked to skin effect.
  • One participant questions whether skin effect applies to current flowing through liquids, suggesting there may be different considerations at play.
  • Another participant discusses the relationship between resistance and the distance between metal plates in water, mentioning that the conductivity of the liquid affects resistance.
  • A participant with experience in electro-chemical machining shares insights on high current usage and expresses curiosity about electron flow mechanisms in electrolytes.
  • It is mentioned that skin effect primarily occurs at high frequencies, and that stranded wire only benefits from this effect if the strands are electrically isolated, as in Litz wire.
  • One participant raises a question about the purpose of multi-stranding in wires, suggesting it may be for cooling, and references the design of high-voltage transmission lines.

Areas of Agreement / Disagreement

Participants express differing views on the relevance and implications of skin effect, particularly in relation to stranded versus solid wire and in liquid conductors. There is no consensus on the applicability of skin effect in all contexts discussed.

Contextual Notes

Some assumptions about the conditions under which skin effect is relevant remain unaddressed, and the discussion does not resolve the complexities of current flow in electrolytes versus solid conductors.

MR. P
Two cases:

1. A #12 solid copper wire is rated for 20a and a #12 stranded wire is rated
for 25a the reason given for greater ampacity is increased surface area
of the stranded wire called skin effect.

2. Does/is skin effect a consideration when current passes through a liquid or
is there a different word or consideration which describes this type of
current flow?
 
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i've done some reading ,in the past , on this subject..
say that you have two metal plates ,in water , and you are passing a current through them .
The resistance is proportional in some way to the distance between the plates , and the make up of the liquid, obviously salt water will have less resistance than tap water, because of the Na+ and CL- ions..
skin effect ? i am not sure..
 
willib

I have some experience with a process known as 'Static ECM' or static electro-chemical machining. In that arena we would use currents as high as 300a to 500a at 7 -12 volts D.C. for a few seconds usually under a minute to 'machine ' a 'deburred' detent for the spring clips that go into the sychronizer ring for manual transmissions. My curiosity has always been the mechanism of electron flow within the electrolyte, which could be basic or acidic depending upon the type of electrodes or machined material we were using.

frank MR. P
 
Skin effect only happens at high frequencies like radio.

Regular stranded wire has no benefit unless the strands are electrically isolated. Then its called Litz wire.
 
thank you cliff I'll double check the lead ,so the multi stranding is for cooling? I know that 500KV transmission lines are hollow... for weight and the inside and outside surfaces for current flow...

frank
 

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