Hardware Spikes 2

[Mbrooke]

Why would there be spikes at the end of an insulator's hardware? Wouldn't they be totally counterproductive? I always thought the goal was to even out the electric field around these parts?

 

[davidbeach]

Spark gap. If the insulator is going to flash over it would be better for it to be in air rather than on the surface of the insulator. Arrestees do a better job since they self extinguish but they’re newer and more expensive.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Mbrooke]

Alright, but wouldn't these lead to some really bad corona discharge?

 

[davidbeach]

Don't know. The only installations of those that I've seen were in Europe and I don't know anything about actual performance.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Mbrooke]

Its alright. Europe has a unique yet respectable way of doing things. I know that every time I like at EU drawings (or pics) I end up learning something new about electrical theory.


Have your toured any EU substations from the inside? I remember you mentioning the grass inside them.

 

[waross]

Those are on the grounded end of the insulators.
The insulators appear to be anchored by cables.
In the event of a lightning strike, the twist in the cables can introduce quite a bit of inductive reactance.
Could a flash-over between those spikes provide an alternate current path in the event of an extremely fast rising wave front?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[sushilksk]

Those are on both ends of the insulators.

Spark gap is provided to protect insulator by avoiding surface flashover. The twist etc, will be in circuit even if flashover is over the surface of insulator.

 

[cuky2000]

The hardware shown in the picture is a combination of an arching horn and grading ring.

- Arching horn is intended to discharge in a flashover condition instead of arching over the insulator.

-Grading ring is used to mitigate corona and make more uniform the voltage gradient between the insulator avoiding overstress in those insulators in close contact with the live conductor.

[sub]NOTE: Grading ring is common to use in porcelain insulator assembly 230 kV and above and more often used in polymer unit. Arching horn on the other hand is not universally used and uncommon in the ANSI marketplace. Some of the rationales are associated with unreliable performance, sensitivity to changes in weather conditions, radio interference, and noise generation above the accepted threshold.[/sub]

For Additional reference see:

https://www.eng-tips.com/viewthread.cfm?qid=449139

 

[Mbrooke]

I take it MOV surge arrestors are not common in the IEC market place?

 

[crshears]

cuky2000 wrote:

arching

This may be picky, but spelling and pronouncing are two different things, dive us crazy though this fact might...

The only time "arch" is pronounced ARK is in words like archangel [ note: not as in arch-enemy ].

These are therefore arcing horns.

BTW, Mbrooke: spikes ARE hardware! [groan]

Just couldn't resist...

 

[cuky2000]

crshears,

Thanks for correcting the typo

 

[cuky2000]

MOV surge arrester is common to use in both the ANSI and IEC marketplaces. Most power and distribution transformers are equipped with MOSA surge arresters and common use in the substation line entrance. Transmission line surge arresters are commercially available but they are slowly penetrating the power market.

 

[itsmoked]

cuky; I'd suggest you make the color-key blocks about 4X bigger as it's very hard to discriminate between the close colors with blocks that small.

Keith Cress
kcress -

http://www.flaminsystems.com