Medium Voltage Wire break down

[Aaro]

The campus that I work at has a run of Medium Voltage Wire that faulted in the conduit years ago before I started working here. I believe that it is a 750MCM size wire. I was told that the wire broke down because it did not have enough amperage running through it. And after enough time water breaks down the insulation. Supposedly the wire is able to dispel the water when it has a larger amount of amperage going through it.

We run 4160/2400V at this campus.

To me this sounds like a made up story. But if it is true, I figure that someone out there would have heard of this. In my way of thinking, a wire needs to be able to survive underground even when the power is turned off for some time.

Anyone heard this theory before? Thanks.

 

[roger]

To me this sounds like a made up story.

And to me as well.

 

[Shaneyj]

A HV contractor I worked with told me the semiconductor between conductor and outer jacket is for that purpose, to provide an amount of current flow to keep the assembly dry.
The cable just needs to be energized.


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[jim dungar]

A HV contractor I worked with told me the semiconductor between conductor and outer jacket is for that purpose, to provide an amount of current flow to keep the assembly dry.
The cable just needs to be energized.


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The semiconductor might serve in this purpose but that is not the reason it exists.
The semicon is intended to provide a voltage gradient for the voltage on the conductor, it does its job even at no load current levels.

Barring extenuating circumstance, your cable failed because nothing g lasts forever. Even with a quality rate of 99.999% some insulation failures will occur.

 

[Shaneyj]

The semiconductor might serve in this purpose but that is not the reason it exists.
The semicon is intended to provide a voltage gradient for the voltage on the conductor, it does its job even at no load current levels.

Barring extenuating circumstance, your cable failed because nothing g lasts forever. Even with a quality rate of 99.999% some insulation failures will occur.

Interesting reading. I hadn’t heard of the principles negated by using a voltage gradient. Thanks for the input.


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[electrofelon]

A HV contractor I worked with told me the semiconductor between conductor and outer jacket is for that purpose, to provide an amount of current flow to keep the assembly dry.
The cable just needs to be energized.


Sent from my iPhone using Tapatalk

I have never heard that, sounds like hogwash. The semicon layer works in conjunction with the shield to evenly distribute the electrical stress and avoid point of stress concentration. IT also "shorts out" any corona discharge which will degrade the cable.