Dried and impregnated cable conductor - what does that mean in IEC 60287? 1

[Krustabas]

Hello

IEC 60287-1-1 standard includes a table with coefficients for skin and proximity effects (ks and kp) for different conductors (round, stranded, hollow etc.). These coefficients are influenced also by the condition “Whether dried and impregnated or not”.

Can anyone help me with the explanation of what does this “drying” and “impregnation” mean in practice and how it can affect the skin and proximity effects? A lot of information can be easily found about impregnation of insulation, but I couldn’t find anything about conductors.



Thank you

 

[7anoter4]

See “Milliken cable” [for conductor cross section area of 2000 to 5000 MCM-1000-2500 square mm]:
For instance:

http://www.nexans.no/Norway/2007/Underground_power_cables.pdf

http://www.jicable.org/2007/Actes/Session_B8/JIC07_B81.pdf

http://www.jicable.org/TOUT_JICABLE_FIRST_PAGE/2011/2011-B10-1_page1.pdf

 

[Krustabas]

Thank you for the information from which I can see how proximity effect is significantly reduced in Milliken conductors. But I'm still not sure what does "drying and impregnation" of a conductor mean? In most textbooks authors simply state: "conductor is round, stranded, dried, and impregnated - therefore take from IEC 60287-1-1 Ks = 1 and Kp = 0.8. If conductor in not dried and not impregnated, then take Ks = 1 and Kp = 1".

I guess the conductor can be dried in order to get rid of residues of organic materials left over during manufacturing process (but it cannot influence proximity effect). Also I can imagine conductor being lubricated to ensure better electrical contact between strands and to make the conductor more elastic (to alow the strands slide a bit). But again - this alone cannot reduce Kp form 1 to 0.8. It must be something else.

 

[Krustabas]

I just received the latest IEC 60287-1-1 standard (Amendment-1 2014-11) and the phrase "Whether dried and impregnated or not" is replaced with "Conductor insulation system" (eventually, after so many years). Now I can select Kp and Ks coefficients according to particular insulation system: "Fluid, Paper, PPL, Extruded, Mineral, or All".

Another good thing with this amendment is that the long awaited new types of aluminium conductors are added - round solid, round Milliken etc.

With this it seems that the thread can be closed.

 

[7anoter4]

Thanks,Krustabas.