When I took EE there was a separate line of study for transmission line and power plants. Some schools have their very own power plant. Those engineers probably never soldered a transistor.

I have contracted with power companies because they don't know ............ They know things I don't care to know. I probably should have known more about POWER but did not want to get into that field.

While I certainly agree that many of their EEs are going to know little beyond things specific to power generation and distribution, I find it a little hard to believe that they have no one that knows enough about sensing and control systems to tackle this task, especially given how many sensing and control systems exist throughout a power network. Even if they don't, it seems odd that, in such a highly-regulated industry, they would turn to a mechanical type that needs direction from strangers on the Internet to do something like this as opposed to asking one of the many companies that they work with that specialize in sensing and control systems to at least recommend a qualified consultant to contract it out to.

 

There is a difference between the person that buys a control system and the person that designs one. They might have gone to the same school.

 

Again, I'm not an EE, I'm a ME and I don't work in the electric corporation. Our company wants to propose a little project to the electric corporation, but I definitely don't have much experience in high voltage, although I do successfully design electromagnetic actuators, solenoids and even a DC motor, but those are low voltage products and pretty straightforward to design and simulate (I use FEMM and JMAG). This project is not really my cup of tea, but once we have an initial concept of cource it will be supervised by proper EEs. All this discussion above is pretty much irrelevant - why do I do that, when I'm going to die from electric shock etc.

 

What you should know is that there are available wound steel cores, that are welded and the sliced ., with what looks like a lapped mating surface so that there will be very little magnetic energy lost when they are assembled. So IF they can tell you how much power is required and the size of the wire it is surrounding, then the rest will be simple, once you locate the company that sells those cores. The size of the core is determined by the power to be captured, and also the size ofthe cable passing thru the center.
You could design an insulation spacer to both hold the cable in the center and to insulate it from the wire around the core. The insulator will be shaped like a large bobbin used with sewing machines. I can visualize it because I have done quite a bit of the mechanical design of the machines, as well as the electrical portions.