They are installing an underground electrical cable in my neighborhood. It has about 20 plastic tubes 4 inches in diameter. I suppose they will have metal conductors inside. Does anybody know about this design? I suppose it is about 750kv. What if water gets inside to tube? Bill B.
Why do you think it is power cables?
Why do you think it is ~750kV? 20 lots of 750kV is rather a lot of power...
It will help cool the cable. Plastic tubes of the ribbed variety often are just push fit into each other and laid on a sand base. No attempt is made to keep water out and they often have small slots in them anyhow, to stop gas build up, etc.. Nice wet ground will take the heat away better and will probably give the cable a longer life.
If it is power cable, then, you are right, it will have metal conductors inside. But the metal conductors will be covered in insulating material and then have stranded steel armour around that, then another layer of insulation. The tube is covered with sand and a strip of bright yellow warning tape laid over that. Electricity distribution companies are rather keen that the electric stays in the pipe.
I can assure you that it is not anywhere near 750KV for that kind of load. That kind of voltage is used for carrying huge amounts of power over vast distances. Power for whole cities. I'd guess the voltage for that load is
30KV or less. Johnneighborhood.
neighborhood.
750kV can't be right. If you can confirm, pls let us know.j In NA.
Bill Browning schrieb:
Hello,
cables for 750 kV have a nominal current of about 700 A, that is 525 MW. A cable with 30 kV and 600 A will carry 18 MW. (single phase calculated) For your 3 MW, 10 to 20 kV should be enough.
Bye
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750KV phase to phase, 3 phases, 700A will be about 910MVA. or about 303MVA per phase.
I agree that 750 seems a little 'high" but 30KV seems a little "low."
snip
mornin,
20 4" pipes can hold a lot of big cables..........Is it only 3MW? Even one fairly small hospital could easily swallow
3MW by itself, could it maybe be 30 or even 300?Out of curiosity, how is power supplied to really large buildings, say
substations are installed in them? I would guess they would take in at least 33kV?
cheers James
-- aykut from tr
BB> They are installing an underground electrical cable in my neighborhood. BB> It has about 20 plastic tubes 4 inches in diameter. I suppose they BB> will have metal conductors inside. Does anybody know about this BB> design? I suppose it is about 750kv. What if water gets inside to BB> tube? Bill B.
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