Telecom lightning arrestor

[Tom Harris]

Greetings,

Passed a derelict country railway station a while ago and went in for a look. On the wall was a panel containing a few of these lightning arrestors that were connected to the open wire lines that followed the track. They light up nicely at 300V ac.

Tom Harris <celep...@gmail.com>

[Tidak Ada]

Hi Tom,

 

Nice find! Can you tell me the values of the resistor you placed in series? I cannot read it from the photo.

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Tom Harris
Sent: maandag 22 september 2014 7:31
To: neoni...@googlegroups.com
Subject: [neonixie-l] Telecom lightning arrestor

Greetings,

Passed a derelict country railway station a while ago and went in for a look. On the wall was a panel containing a few of these lightning arrestors that were connected to the open wire lines that followed the track. They light up nicely at 300V ac.

Tom Harris <celep...@gmail.com>

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[Tom Harris]

I used 10K, but they are built to take a lot of current, so I could probably drop it down. The electrodes are probably tungsten. I'll have a photoshoot of the lot, as I ended up with a lot of different sizes. I might go back and score the bakelite mounting clips as well.

Tom Harris <celep...@gmail.com>

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[Tidak Ada]

Keep in mind most of these tubes have a radioactive doping for better arcing. So don't break the glass!

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Tom Harris

Sent: dinsdag 23 september 2014 0:57
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Telecom lightning arrestor

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[Tom Harris]

Thanks, I'll check if it ionises the air by bringing it near a spark gap just off arcing over, an excellent test for radiation, and far more spectacular than discharging an electroscope as a demonstration of radioactivity.

Tom Harris <celep...@gmail.com>

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[gregebert]

I'm curious how long these devices would last if they were operating continuously at a low current (just enough to get a visible discharge).

Despite being 'old technology', gas-filled arrestors are advantageous because they have low capacitance and very low off-state leakage.

[Tom Harris]

Well I half-destroyed one with an overcurrent by connecting it to 300V AC with a 150W lamp as a current limiter. It gave a bright red neon discharge on both electrodes and a lovely pale blue space discharge for about 10 secs. Now it needs about 350V to fire with a 10K series resistor. I shall test another one with a more moderate current and see how it lasts.

Tom Harris <celep...@gmail.com>

On 24 September 2014 08:19, gregebert <greg...@hotmail.com> wrote:

I'm curious how long these devices would last if they were operating continuously at a low current (just enough to get a visible discharge).

Despite being 'old technology', gas-filled arrestors are advantageous because they have low capacitance and very low off-state leakage.

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[Tom Harris]

More on the arrestor, I tried it this morning and it has got better overnight, it just strikes at 290V, before it was not striking reliably at 300V. It must have been tuckered out. It looks like it is recovering slowly.

Tom Harris <celep...@gmail.com>

[Tidak Ada]

Such arrestors actually have to withstand kA's for a short discharge! Look at your overvoltage protector you use (hopefully) for your computer and peripherals. I have here a Belkin contact block that is guaranteed  for 40,000 A.

Belkin says to compensate all equipment connected to it that will be damaged in case of a surge voltage for life time (of the protector).

I once hat such a case and got a new contact block without troubles. There was no damage to the protected equipment, only the surge protector died in service.

More modern surge arrestors have a ceramic housing, so they aren't spectacular.

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Tom Harris

Sent: woensdag 24 september 2014 2:21

To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Telecom lightning arrestor

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[Tom Harris]

Yes modern ceramic arrestors are rated for KA! I expect my glass ones are similar. But they are far nicer to look at than modern ones. We need more components encapsulated in glass, modern ceramic are so boring.

I tested mine this eening, it has gone  back to striking at the same voltage as it did before I gave it a hard time!

Tom Harris <celep...@gmail.com>

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