Re: power line insulators

[Jossem@MPS.OHIO-STATE.EDU (E. Leonard Jossem)]

>        I've looked at many sources but can't seem to find an answer to
> this:  Why are the ceramic standoff insulators on the high voltage power
> lines shaped the way they are?  I looked up the resistivities which are on
> the order of 10^10 ohms, so I don't think the leakage currents are that
> high that the "fins" on these things are needed for cooling.  Any clues?
>
>
>                                Mike Monce
>                                Connecticut College

For these insulators the surface leakage resistance is an important factor.
The "fins" increase the surface leakage paths  by a considerable factor
over what it would be with a simple cylinder or cone shape. This is of some
importance because these insulators are out in all kinds of  weather (rain,
snow) and accumulate stuff (dirt, etc.) on their surfaces.

Best regards.