Re: Power Line Insulators

[David Kardelis <dkard@CEU.EDU>]

As a matter of some interest reading this thread because we had a dry fall
this year and the bird
doo built up on the insulators on the power transformers for the town. Well
in mid jan., we had a long rain storm first one in several months and the
power went out. Turns out the water dissolved the bird doo on the
insulators- creating a conducting path. I guess you could see the sparking
several blocks away. It started the wood poles on fire and we had to cancel
class for a day as there were no lights in town.  It was pretty funny
reading about it in the paper.
        If your interested it can be found at www.sunad.com the JAN 20,2000
EDITION

dave

-----Original Message-----
From: Leigh Palmer [mailto:palmer@SFU.CA]
Sent: Monday, April 10, 2000 2:57 PM
To: PHYS-L@lists.nau.edu
Subject: Re: Power Line Insulators


> I've been watching new power poles go up around our campus and it
> occurred to me that the insulators that hold the wires always have the
> same basic shape:  what appears to be ceramic "disks" stacked together.
> I've tried to think through why this shape is important, but so far I've
> come up empty.  Does it perhaps have to do with moisture shedding?  An
> increased surface area would get rid of heat more efficiently, but these
> insulators shouldn't get that hot anyway, right?
>
> I'm likely missing something really simple, but I'd appreciate it if
> anyone out there knows the answer, please give me a clue.

The object of this design is to provide long-lived insulation in a small
package. As the insulator is subjected to fallout from rain, snow, birds,
insects, and dust it develops a leakage path to ground. The corrugations
on the insulator provide two things. They lengthen the surface path
length over which this crud can accumulate, and they provide some degree
of geometric shielding against some of the aforementioned insults.

Leigh