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W6KWF > TECH 03.10.21 19:07l 43 Lines 2360 Bytes #999 (0) @ WW
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Subj: Scattergood-Olympic Line 6/7
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Sent: 211003/1751z @:W1XSC.#NCA.CA.USA.NOAM [Santa Clara Co] #:9768 $:09766_W1X
Jim says the fault lasted 20 milliseconds before breakers tripped. (The
breakers for a wire like this are pretty amazing in their own right.
They use high pressure gas to blow out the arc as the circuit begins to
open. Anything that can cut off this number of megawatts in 20 ms gets
my respect.) It blew carbonized oil about 3000 feet down the pipe to
either side of the fault. (Compute velocity...)
They will be removing a long length of cable from the faulted area for
analysis. The entire length will be dissected. Jim says the insulation
they have inspected at so far looks like shredded cauliflower due to the
explosion from the fault and the gas bubbling in it. (BTW - The
insulation consists of 118 layers of paper tape.)
Based on X ray imaging they are going to have to open up 14 of the 23
splices along the 10 mile run. They'll have to drain the pipe to do so.
It will take them 2 months to take the pipeline down (depressurize and
drain). (The oil will be recycled - see below.) At each of the opened
splices they are going to install special aluminum (non magnetic)
collars around the conductors to keep the splices from getting pulled
into the necked-down section of the pipe. These collars are being
specially fabricated now and will be ready in about a month.
At each splice they have to build a semi clean room to keep dirt,
moisture, worker sweat, and any other contaminants out of the joint
before closing. After all, we're talking a quarter megavolt! They have
special air conditioning and filter units for the vaults. Each joint
will take two months of work. They will get some degree of parallelism
in the phase of the project.
After repairing and replacing the faulted section of cable, stabilizing
all of the splices, and buttoning it all up comes the job of putting the
oil back in. First the pipe is evacuated and then back-filled with
nitrogen etc as I described earlier. After extensive filtering, the oil
is heated to about 230 degrees farenheit. It gets injected into a vacuum
chamber at the temperature thorough hundreds of spray nozzles. This gets
the maximum possible surface area so all the crap in it boils out into
the chamber. The good stuff that's left is collected and pumped
immediately into one end of the pipeline.
Then they power it up and see if it works. If not, they start over
again. I'll keep you posted.
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