W6KWF > TECHNI 03.10.21 20:00l 41 Lines 1881 Bytes #999 (0) @ WW
BID : 09748_W1XSC
Subj: Scattergood-Olympic Line 2/7
Sent: 211003/1745z @:W1XSC.#NCA.CA.USA.NOAM [Santa Clara Co] #:9750 $:09748_W1X
That's where the LN-2 comes in. An elegant solution if you ask me. They
dig holes on both sides (20-30 feet each way) of the fault, wrap the
pipe with giant (asbestos-looking) blankets filled with all kind of
tubes and wires, feed LN-2 through the tubes, and *freeze* the oil.
Viola! Programmable plugs! The faulty section is drained, sliced, the
bad stuff removed, replaced, welded back together, topped off, and the
plugs are thawed. I was amazed.
The next day:
Last night the DWP held a curbside chat to allay the neighborhood's
fears that they were going to accidentally blow us all up. Apparently
all the vapor clouds from all the LN-2 blowoff had caused a great deal
The feeder was laid 17 years ago and was designed to have an MTBF of 60
years. There are other similar feeders in use around California, in the
Pacific North West, and some on the east coast. This was the first
failure in the western US. No one out here had any idea how to fix it so
they brought in experts from the east. (NYC has had some faults.)
This link is a very critical part of the LA power grid. Last night the
city engineers verified the $13,000 per hour power cost figure quoted
the day before. (I guess that means they are being forced to buy power
off the grid somewhere else.)
There are actually three center conductors (they had a cross sectional
model to show us). Each is about 3" in diameter with a one inch solid
copper core. Each is wrapped with hundreds of layers of a special paper.
That, in turn, is sheathed with copper and then each one is
spiral-wrapped its entire segment-length with a 1/4 inch bronze "wire".
The three conductors are then twisted together during the pulling
process. The bronze spiral wraps form a kind of linear bushing with
minimal contact area with the inside of the pipe so it's "easy" to pull
each segment. Ha.
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