Shield Corrosion

Do you have information about copper corrosion on energy cables? " shield corrosion "

Hello Jachpa,

What are you referring to?

Are you talking about concentric neutral jacketed cable where the concentric copper wires have been exposed to water because of faulty manufacturing practices (Jacketing), damaged jackets or poor jointing?

Are you talking about fully copper screened (Helical or longitudinally taped) and jacketed concentric neutral cable exposed to water as per that described immediately above?

Are you talking about long term migration of water vapor through the jacket and into the concentric neutral air spaces in the cable by Dalton's Law of Partial Pressures? This was extensively studied in telephone cable and resulted in the "Glover Barrier" concept which is still used today in telephone cable, power cable and optical fiber cable.

Note that in all these instances, the common thread is water.

Best regards,

Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

I am talking about long term migration of water vapor through the jacket. The corrosion is in the copper between the maylar tape and semi-conductive. This corrosion is powder on green or blue color.

Hello Again,

Take a look at this Dow Chemical Company web page (PDF Document):

www.dow.com/PublishedLiterature/dh_005c/...fromPage=BasicSearch

You will have to get technical literature from the Dow Chemical Company ( www.dow.com/zetabon/ ) re Glover Barriers for power cables using their Zetabon(R) tapes but there is lots to read here:

www.dow.com/zetabon/nrc/over.htm

Remember that there must be room for thermal expansion of the cable core so that the Glover Barrier is not destroyed.

Moreover, as I recall, there were a lot of papers given on this subject at the " International Wire and Cable Symposium"" www.iwcs.org/ in the late 1960s and the 1970s. Perhaps if you contact them, they can help you by providing you with reprints of those papers.

You should also read the Forums thread titled "Oxidized Copper" at www.wireassociation.com/forum/viewmessag...m?Forum=12&Topic=387

The green and blue-green powder colors are sulfates of copper and I guess the basic question is; "Where is the sulfur coming from?"

This should be adequate information to get you started!

Best regards,

Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com