HV pylons

spud1 · Dec 31, 2011

Hi,

Does anyone know what the congregated discs shaped things are at the end of an HV distribution cable are for on electricity pylons ?

Are they to help with stopping conductance through rain in bad weather ?
Are they indicative of the voltage being distruted by that particular cable ?

I always wondered.....

Amp David · Dec 31, 2011

Insulators, they are where the transmission lines are attached to the pylon.

spud1 · Dec 31, 2011

Thanks Amp. Why are they shaped so?

Amp David · Dec 31, 2011

Maybe for the ease of replacement, not sure though

spark 68 · Dec 31, 2011

They are disc shaped to create a longer path (Gap) than would otherwise fit in the same available space.

johnboy6083 · Dec 31, 2011

As above, it's more surface area for the electricity to track across.

Simlec · Dec 31, 2011

Aren't they shaped like that to allow the water to run off and stop a short due to water running down them?

spark 68 · Dec 31, 2011

Are they indicative of the voltage being distruted by that particular cable ?

I believe that if you know what the 'breakdown voltage' of each disc is, you can calculate (roughly) the line voltage, by counting the number of insulators (discs).

spark 68 · Dec 31, 2011

Aren't they shaped like that to allow the water to run off and stop a short due to water running down them?

That was not the primary function, it is to increase the distance the 'arc' would need to track, sort of around the edge of the disc.

Silly Sausage · Dec 31, 2011

What johnboy & spark said.
Also, they are round to avoid any corners, electric fields are more concentrated at sharp points, to reduce chance of arcing.
They're also cone shaped, so when strung vertically, the underside remains dry in wet weather.