MV Cable Shield Type

[rockman7892]

I have typically seen Medium Voltage cable with a copper tape shield between the conductor and the insulation in order to provide a uniform grounded shield on the cable. In speaking with a facility recently they mentioned that because of the plant environment they have had issues in the past the copper shield corroding and have thus specified a MV cable with a bare copper concentric conductor with the intent of using the concentric conductor as the cable shield and terminating shield to stress cones as you would with the tape shield.

I was curious if there was any advantage or possible disadvantage to using this concentric conductor shied as opposed to using the tape shield that I have typically seen on most cables? The concentric shield does not seem like it would provide as much as a uniform distribution that the tape shield would.

 

[Marmite]

Normally with a copper wire screen you also get a semiconducting compound layer between the insulation and the screen wires which evens out the voltage stresses.

See attached data sheet.

Regards
Marmite

 

[Jebb]

I would think whatever is corroding the copper tape will also corrode the concentric conductor over time. Did the corrosion of the screen happen only once or is it an ongoing problem?

 

[7anoter4]

See also:
thread238-62281