🚀 go-pugleaf

In article <7578@felix.UUCP>, dennisg@felix.UUCP (Dennis Griesser) writes:
> In response to mercury-filled speaker cables, Larry Lippman <1997@kitty.UUCP>
> warned about the toxic hazard presented by mercury.  Then he said...
> 
> >	Now, for a more practicable idea, consider the use of SODIUM-filled
> >cables, which have been available to the electric power industry for a number
> >of years.  Sizes go up to at least 500,000 circular mils, and I know for a
> >fact that the cable is available with an insulation rating of 15 kV for
> >direct-burial applications.
> 
> Sodium-filled cable really does exist.  Many years ago, my father worked in
> Union Carbide's NaCon division where they were being developed.
> 
> What Larry failed to mention, and should have since he was reminding us about
> the dangers of mercury, is that sodium reacts vigorously with water.  The
> insulation needs to be quite water-tight, and terminating the ends must be
> interesting.

	I was being facetious, so I didn't mention it!

	Sodium has approximately 40 percent of the conductivity of copper,
so it's not that bad a conductor.  Sodium has about 1/3 the density of
aluminum and about 1/10 the density of copper.  Sodium-filled cable is
extremely lightweight when compared to that of copper or even aluminum.
	Sodium is a byproduct of chlorine production, is quite plentiful,
and costs less per pound than aluminum.
	The use of sodium for underground high-voltage cables (4,160 volts
and above) awaited the development of a practicable cable manufacturing
process, and of a practicable and safe connection method.
	Sodium-filled cables for underground high-voltage distribution have
been used for at least 20 years.  The cable terminations have a "corkscrew"
which digs into the sodium filling inside the cable; this termination has
a plastic sheath which fits over the end of the cable and seals it with a
cement.  A conventional terminal lug protrudes from the cable termination
for connection to distribution apparatus.
	Besides being of low cost and light weight, sodium-filled cables
have the advantages of fault limitation and easy fault localization.
Unlike conventional cables which might have a fault (say, an insulation
defect or injury) with slowly increasing leakage to ground, the slightest
leakage in a sodium-filled cable causes rapid destruction of only a small
portion of the cable.  Following such a fault, the formation of sodium
hydroxide at the exposed ends of the cable seals the remainder of the
cable from moisture penetration beyond a few feet.
	Speaking as both an EE and chemist, I feel that sodium-filled
cable is an effective means of providing low-cost underground electric
power transmission for voltages between 4.16 and 34.5 kV.  However,
sodium-filled cable has been severely under-utilized.  I don't know why
this is, other than there appears to be some unfounded apprehension about
its use.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
<>  UUCP:  {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry
<>  VOICE: 716/688-1231       {hplabs|ihnp4|mtune|seismo|utzoo}!/
<>  FAX:   716/741-9635 {G1,G2,G3 modes}   "Have you hugged your cat today?"