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Re: [TCML] Frying tesla coil



bartb wrote:
Garry,

There are cases of metal fragments in pvc, but it's rare. Gary Lau's account of seeing a similar issue with a turn to turn short is certainly viable. He is simply telling you an occurrence he had. But to just "guess" that it's a metal fragment without pursuing the factual cause? Dig in there.. If it's a metal fragment, find out. You don't want a secondary with a metal fragment do you? Look closely also at the wiring to pin-point the specific area. If it's a metal fragment, get rid of it. I feel as Gary does that a metal fragment did not cause your incident. But only you can verify. Again, it does happen I guess, but it's been a very rare occurrence from the reports I have heard of over many years here on the TCML..

Regards,
Bart



---------- Forwarded message ----------
From: *Garry Freemyer* <garryfre@xxxxxxxxxxx <mailto:garryfre@xxxxxxxxxxx>>
Date: Tue, Jun 1, 2010 at 10:04
Subject: Re: [TCML] Frying tesla coil
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx <mailto:tesla@xxxxxxxxxx>>


Hmm, now that is much more believable than Gary Lau's idea that after hours and hours of operation, it was over-coupling, I think I'll go in and amend my video to say it is still a mystery and say some suggest it is material in the form but later I'm told they have strict rules about this and that it could be that the insulation simply broke down. I did find what looked like metal fragments in the form in three different places rather deep, but it could have been silver paint, or who knows.

I definitely remember a member saying that the place where he worked dumped floor sweepings into the vat of molten plastic but now I find myself irritated that someone would say this when maybe it didn't happen. I believed them and now I feel like I've been made a fool of.




________________________________
From: Quarkster <quarkster@xxxxxxx <mailto:quarkster@xxxxxxx>>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx <mailto:tesla@xxxxxxxxxx>>
Sent: Mon, May 31, 2010 11:23:09 PM
Subject: Re: [TCML] Frying tesla coil

Gary -

I think that it is MUCH more probable that what is shown in your video clip is a simple insulation breakdown and turn-to-turn short between two adjacent turns on your secondary. Over the years I have personally seen this happen twice, and both times the appearance was EXACTLY what is shown in your clip.

 Facts about plastic extrusiuon machines:
1. Because of the high cost and fine finish on extrusion dies, every precaution is taken to ensure that no abrasive material is ever allowed into the material hopper. 2. Extruders are almost universally equipped with wire mesh "filter screens" that filter out any particles of foreign that may accidentally be introduced with the resin granules. Google "extruder screens" to see how fine these screens are.

As far as seeing darker specks or blobs in white PVC, this is easily explained by any one of several different sources:

1. Extruders may run different color materials at different times. Although every effort is made to purge the machine of the previous material, small chunks of material may get stuck in the feed screw or other areas. Later, when a different color material is being run, these chunks may finally break free and pass into the extrusion stream, where they end up in whatever material and shape the extruder is currently running.

2. Bits of material may get stuck in the melting zone of the extruder, where they eventually start to breakdown (carbonize). Bits of this material may slough off from time to time, and appear as dark specks or patches in the extrusion.

Best regards,
Quarkster

--- On Mon, 5/31/10, Garry Freemyer <garryfre@xxxxxxxxxxx <mailto:garryfre@xxxxxxxxxxx>> wrote:


From: Garry Freemyer <garryfre@xxxxxxxxxxx <mailto:garryfre@xxxxxxxxxxx>>
Subject: [TCML] Frying tesla coil
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx <mailto:tesla@xxxxxxxxxx>>
Date: Monday, May 31, 2010, 6:16 PM


This is a video of my tesla coil frying due to foreign matter in the PVC pipe that forms the secondary.

One person on the list mentioned that they sweep the floor and dump it all into the molten plastic so PVC can contain metal fragments, bug parts, hair, wire, screws etc etc.

I was surprised how easy it was to upload videos to Youtube...

http://youtube.com/watch?v=L_40Oq3UKVY
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