Skin effect or total crossectional area

MR. PIn summary, the difference in ampacity ratings between a #12 solid copper wire and a #12 stranded wire is due to the increased surface area of the stranded wire, known as skin effect. This effect is not a consideration for current passing through a liquid, but is relevant in processes such as static electro-chemical machining. Stranded wire can also have cooling benefits if the strands are electrically isolated, and is referred to as Litz wire.
  • #1
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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  • #2
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..
 
  • #3
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
 
  • #4
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.
 
  • #5
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
 

Related to Skin effect or total crossectional area

What is skin effect?

Skin effect is a phenomenon in which high frequency current tends to flow on the surface of a conductor, rather than through its entire cross-sectional area. This is due to the inductance of the conductor, which causes the current to concentrate near the surface.

How does skin effect affect the total cross-sectional area?

Skin effect reduces the effective cross-sectional area of a conductor, as the current is only flowing through a thin layer near the surface. This means that a larger conductor may be needed to carry the same amount of current at high frequencies compared to low frequencies.

What causes skin effect?

Skin effect is caused by the self-inductance of a conductor, which creates a magnetic field that opposes changes in current. As the frequency increases, the inductance becomes more significant, causing the current to flow on the surface where the magnetic field is weaker.

How does skin effect impact the performance of electrical systems?

Skin effect can increase the resistance of a conductor, leading to power loss and heat generation. This can affect the efficiency of electrical systems and may require additional measures, such as using different types of conductors or designing for lower frequencies, to mitigate its effects.

How can skin effect be minimized?

Skin effect can be minimized by using conductors with a larger surface area, such as stranded wires or hollow tubes, which allow the current to flow through more surface area. Another method is to use conductors made of materials with lower resistance, such as copper or silver, which can reduce the overall power loss due to skin effect.

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