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GeordieBoy

Tue Mar 23 2010, 10:44PM

Registered Member #1232 Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881

Episode 2 of Richard Hammond's Invisible Worlds had an interesting feature about detection of corona around high voltage apparatus using an Ultra-Violet video camera. The corona camera footage is from 2m:17s to 9m:19s on BBC I-player for those who missed it:

The feature about "heater bees" in the hive is also in this episode from 38m:00s onwards...

Enjoy,

-Richie,

Proud Mary

Tue Mar 23 2010, 10:50PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

My, that's interesting, Richie.

I have for some time been interested in using Schlieren photography to image points of extremely high PD, but one can't do everything in a single lifetime, so perhaps someone here will pick up the idea up and do something interesting with it.

IntraWinding

Wed Mar 24 2010, 02:07AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

I watched Episode 2 of Richard Hammond's Invisible Worlds on BBC1 this evening. The images of corona on power lines looked extremely suspect to me. It looked a bit like the kind of rubbish special effects used years ago where they actually scratched on the film frames, in a modern way of course. I mean it looked like it had been drawn in by hand using some computer video editing system, badly.

In fact I spent most of the program getting progressively more annoyed as Richard Hammond kept claiming things could now be seen 'for the first time' when actually they've been doing most of it, or better, for years. Last week he annoyed me with similar claims about high speed photography. Slow motion shots of drops falling into water were presented as though this was all astounding new stuff. This is what I call astounding, and it was 70 years ago!

Anyway, as I remember helicopters are used to detect faults in power lines using IR to spot overheating from leaking current, not UV to spot corona. I think Richard Hammond's just making half of this up. He had too many examples of Infrared and not enough about UV so turned the overhead power line story into one about UV by cheating. Or am I wrong?
What about his explanation for the penetrating effect of X-Rays being a consequence of them being so powerful

Better to say nothing than mislead.

Coronafix

Wed Mar 24 2010, 02:32AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Only available to watch in the UK unfortunately.

tobias

Wed Mar 24 2010, 09:54AM

Registered Member #1956 Joined: Wed Feb 04 2009, 01:22PM
Location: Jersey City
Posts: 172

Coronafix

Configure your browser to use any UK proxy and the site will believe that you are actually in UK! You can try lists like this:

Or just google "uk proxy list" or something like it.

EDIT: I have success playing it from Brazil using this config:

Good luck!

GeordieBoy

Wed Mar 24 2010, 10:56AM

Registered Member #1232 Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881

The images of corona on power lines looked extremely suspect to me. It looked a bit like the kind of rubbish special effects used years ago where they actually scratched on the film frames, in a modern way of course.

I think that is just how it looks when the UV picture is overlaid onto the visible one.

The UV camera finds sharp points where corona is being produced or insulators that are on the verge of breaking down and partial discharge is taking place. It doesn't find hot-spots due to high resistance in poor electrical connections. The IR camera is used to find those, hopefully before they get worse and melt!

UV light, ultrasound and radio-frequency emissions are all commonly used to detect partial discharge in high-voltage equipment. A HV insulator that is experiencing partial discharge is presumably not only leaking charge away to it's surroundings, but is also emitting considerable radio-frequency interference and ultrasound too!

-Richie,

Proud Mary

Wed Mar 24 2010, 12:05PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

There is also the Megger 569001 Ultrasonic Leak/Corona Detector about which:

The Ultrasonic Leak and Corona Detector is a low-cost, portable system that receives air-borne ultrasonic signals, converts them to the audible range, amplifies them and displays the output visibly on a meter and audibly through a speaker or headset. The system is designed for locating gas leaks and electrical corona sources, all of which emit strong ultrasonic signals that are inaudible to the unaided human ear. Variously shaped collectors facilitate quick location of ultrasonic sources; in particular, the new directional pickup horn allows pinpointing of discharges in high-voltage equipment while the operator remains at a safe distance.The ultrasonic detection system shown above consists of the instrument with indicator and speaker, plug-in ultrasonic transducer probe, directional pickup horn attachment, sound concentrator attachment and a headset. A carrying case is included.

I recall seeing an amateur design for a very directional bat detector which used a small satellite TV parabolic, and was strongly influenced by the Megger instrument.

Were the parabolic silvered on one side, perhaps the sonic and optical techniques could be made to work in tandem.

Steve Conner

Wed Mar 24 2010, 12:29PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

That is how the CoronaCam works, it has a low-resolution UV camera whose output is overlaid on the output of a regular video camera.

I've been working on this stuff since 2007, here is some info on the instrument we made:

IntraWinding

Wed Mar 24 2010, 01:02PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Apologies to Richard Hammond Re: the CoronaCam thing.
So in that case it was new technology, to me anyway!

Killa-X

Wed Mar 24 2010, 07:34PM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

So that's what that video was about that I found a week ago,(GeordieBoy youtube links) Showing the white marks on the power lines and their insulators. Wondered what it was at first and saw it was a corona camera..Come here a week later and I find this :D Cool stuff!

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