MV cable damage
MV cable damage
(OP)
I have the following Cable: Uniblend, Spec 6350, 250 kcmil: EPR/Copper Tape Shield/PVC, Medium-Voltage Power, Shielded 15 kV, UL Type MV-105. 1.25” overall nominal cable diameter. IAW NEC and mfgr specs the min bend radius is 15" It has been pulled through a Greenlee 9 ¾ radius sheave at ~4000 PSI, at a ~1300’ length with the sheave ~center of pull at 90 degrees. You can see where the shield ribbon pulled nearly apart on the outside and bunched bunched up when straightned. And on the sheave contact side is wrinkled. What does this do to the longevity?? Is there any danger ever?? Has this in any way degraded the performance of the cable???






RE: MV cable damage
You might be able to do a hi-pot test and verify some of the cable integrity. But that test will not find all of the possible failures. I am not sure if a partial discharge test could locate potential failure points.
RE: MV cable damage
The bending radius your referencing is static or traning radius.
The 9 -3/4 in sheave put about 4,900 lbs/Ft of side wall pressure on the cable. The usual limit is 300-900 lbs/Ft.
At the "To" end of a pull it's common to use a segimented sheave with a large effective radius.
RE: MV cable damage
RE: MV cable damage
RE: MV cable damage
apart from the above points the damaged screen may not be able to deal with earth fault current so in the event
of earth fault current flowing through the damaged
section of screen you could get further faults on the cable
its scrap by the sounds of things.
RE: MV cable damage