Cable Swell

[farmape]

Do medium voltage (5-15kV) cables (shielded power cables) "swell" over time when subject to constant moisture, laying in water?
If this "swelling" is evident, is it indicative of the remaining life of the cable?
Thanks

 

[Zogzog]

They shouldnt swell, if they do you might have a problem. Conduct a Tan Delta test.

 

[oldfieldguy]

I had problems with MV cables swelling, but the "water" in question had a high amount of various interesting hydrocarbons incorporated. Interstingly, the cable remained in operation until it was "blown' by a goof-ball who was "testing" it with a DC Hipot.

old field guy

 

[BJC]

Water in the conductor will make them swell. It's not uncommon. Most cable companies have proceedures for removing the water.

 

[Zogzog]

N2 purge, I have that procedure around here somewhere

 

[ausphil]

we have had a number of aluminium conductor cables swell and ooze a white fluid (al oxide) due to moisture ingress. The outer sheath ends up splitting, and exposes the conductor to the earth, which then adds a OHS risk to staff or contractors digging in certain locations around this problem - people getting tingles off shovels and crow bars etc.

 

[farmape]

Wow this is very interesting. I wouldn't have believed it until I saw it myself,and now I know it is possible.
I assume the cables would need to be completely accessible to remove the water, which is unrealistic in my case.

 

[jghrist]

If water gets into aluminum cable, and sits there long enough for aluminum oxide to form and swell, the remaining life is pretty close to zero. I don't think you'll ever purge the water out adequately and aluminum oxide is a lousy conductor.