"Semiconductor" sheath on cable?


A friend is an electrician who works mainly on intallations at factories, etc. He has a beverage coaster made from a thin cross-section of a "primary" cable, the kind that brings power into the plant. It has a central conductor area of many strands of heavy-gage wire, then an insulating sheath of something rubbery that looks sorta like that red HV silicone rubber, then a very thin metallic layer which he called a "semiconductor shield" before the final insulating jacket.

I tried to find out exactly what he meant by "semiconductor" in this context because I couldn't picture silicon or germanium, for example, being made into a flexible foil. (Well, maybe not *too* flexible, since the cable was several inches across!) He said he really didn't know about such things, but that the layer was supposed to reduce the magnetic fields from around the cable, which otherwise were a problem at the high voltages and currents involved. (Which he also didn't know the levels of.)

Anyone familiar with this technology?


Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

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Reply to
Bob Masta
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No, but I think he means "partially conducting" rather than semiconductor as in solid state devices.

Decades ago, I was given a bit of that stuff, I think it was left over from a TV transmitter installation. It did indeed have some conductivity, but not all that much. I played around with it at the time, because I was interested in electronic music at the time and there were various controllers based on that sort of thing. But memory says I didn't find that there was a good relationship between length and resistance. It just seemed to have some conductivity, period.

The thing I had was rubber, and it most definitely came from a power line cable. If I heard a reason for its purpose at the time, I've long forgotten.


Reply to
Michael Black

From what Michael Black said, it's "partially-conductive" material, probably a lot like that foam that they used to ship chips in.

I'm guessing that it would "suppress" the magnetic field around the big conductor by eddy currents/back EMF. And of course, since it's resistive, it has a Q of squat, so instead of a big magnetic field around the conductor, you have a hot cable.

Cheers! Rich

Reply to
Rich Grise

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