Oblsss
Electrical
- Nov 7, 2013
- 42
Hello everyone,
A number of cables of the type described below have been installed in 600 meter long 3-phase circuits.
Bundled MV cable consisting of three single cores each with aluminium conductor, XLPE insulated and laid up in bundled formation with a semiconducting tape(water swellable)used as a binder.
Aluminium wires laid helically along the semiconducting tape.
A second semiconducting tape(also water swellable)above the aluminium wire screen.
Polyester laminated aluminium foil of very small thickness wrapped around the above layer and bonded to the polyethylene overall jacket.
The cable type described is similar to the one you can see in the link mentioned below but with one more semiconducting tape between the aluminium wire screen and the Polyester laminated aluminium foil.
axalj-f-tt
Either during the storage of the cable in the cable drum (with a small internal drum diameter) or during the installation of the cables by the contractor (excessive pulling tension in the sleeve or extreme bending of the cable), we had several broken wires in the aluminium wire screen. The latter was realized only during the stripping of the outer sheath for the termination of the cable cores, ie after the completion of the cable laying.
I need a reliable method for field measurement of aluminium wire screen resistance to see if:
1) The cable is still operational, ie the screen resistance can carry the expected earth fault.
2) The problem is limited to the cable ends (excessive pulling tension in the sleeve).
3) Which number of the 3-phase circuits have the same problem.
The best solution seems to be this Concentric Neutral Resistance Tester but, at least in my experience, I have never seen something similar in site (Europe or Africa).
Any advice is welcomed!
Thanks in advance,
George
A number of cables of the type described below have been installed in 600 meter long 3-phase circuits.
Bundled MV cable consisting of three single cores each with aluminium conductor, XLPE insulated and laid up in bundled formation with a semiconducting tape(water swellable)used as a binder.
Aluminium wires laid helically along the semiconducting tape.
A second semiconducting tape(also water swellable)above the aluminium wire screen.
Polyester laminated aluminium foil of very small thickness wrapped around the above layer and bonded to the polyethylene overall jacket.
The cable type described is similar to the one you can see in the link mentioned below but with one more semiconducting tape between the aluminium wire screen and the Polyester laminated aluminium foil.
axalj-f-tt
Either during the storage of the cable in the cable drum (with a small internal drum diameter) or during the installation of the cables by the contractor (excessive pulling tension in the sleeve or extreme bending of the cable), we had several broken wires in the aluminium wire screen. The latter was realized only during the stripping of the outer sheath for the termination of the cable cores, ie after the completion of the cable laying.
I need a reliable method for field measurement of aluminium wire screen resistance to see if:
1) The cable is still operational, ie the screen resistance can carry the expected earth fault.
2) The problem is limited to the cable ends (excessive pulling tension in the sleeve).
3) Which number of the 3-phase circuits have the same problem.
The best solution seems to be this Concentric Neutral Resistance Tester but, at least in my experience, I have never seen something similar in site (Europe or Africa).
Any advice is welcomed!
Thanks in advance,
George