138 kv underground lines
#1
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Thread Starter
138 kv underground lines
Not exactly a DIY issue, I am just looking for a resource or pointer.
I was out on a bike ride earlier (beautiful day today) and ran across a spot where one of the overhead 138KV lines goes underground to feed my local substation. I was doing a little googling and found out about this HPGF/HPFF cable http://www.okonite.com/paper-cable.html and a story about installation of such a line underwater and so on.
But I am more interested in how this operates, which I couldn't find any info about. For example presumably there's a compressor-chiller station at the substation and it pushes chilled gas or liquid through the cable - but what happens at the far end? Is there a refrigerant loop in the cable or what? What kind of tonnage is required?
There's just a box about 2x2 feet in the overhead terminus where the UG cable comes up, but there is a large building at the substation that has fans and noise beyond the usual substation hum.
Thanks for any info or pointers.
I was out on a bike ride earlier (beautiful day today) and ran across a spot where one of the overhead 138KV lines goes underground to feed my local substation. I was doing a little googling and found out about this HPGF/HPFF cable http://www.okonite.com/paper-cable.html and a story about installation of such a line underwater and so on.
But I am more interested in how this operates, which I couldn't find any info about. For example presumably there's a compressor-chiller station at the substation and it pushes chilled gas or liquid through the cable - but what happens at the far end? Is there a refrigerant loop in the cable or what? What kind of tonnage is required?
There's just a box about 2x2 feet in the overhead terminus where the UG cable comes up, but there is a large building at the substation that has fans and noise beyond the usual substation hum.
Thanks for any info or pointers.
#3
The buried cables are pressurised with gas or liquid ( oil). Both ends of the cable have pressure sensors on them. When the cable pressure drops, it generates an alarm so that the electrical company knows that there is a problem with the cable. A slow pressure drop indicates that there is corrosion in the cable and that the insulated value of the cable is no longer good and need to be fixed.