Problems with carbon composite in a HV string.

Maynard A. Philbrook Jr. · 2014-05-04T16:52:30+00:00

We have this situation where a section of a string of 22Meg@ 2 watt carbon composite resistors may physically split down the sides there for both lead wires of course become detached. This may happen to several in the same section string. This is a problem that has recently sprang up after a replacement of several sections that showed signs of over heat due to many hours of service and other events, but not splitting.. So I think it has something to do with the way the new strings are being assembled and installed. To let you get an idea of how this is being used.. This is the resistor string inside of the rectifier stack that generates the 1 to 2 Mev volts for an accelerator. When the oscillator is at full potential on this unit, a max of ~ 2Mev with no loading is achieved and it'll drop down to 1.5Mev loaded. The resistor string connects to the High end and spirals down the center to the back end of the vessel, where it comes to a J-box which has a spark plug there gapped for 5th of an inch. This comes into play only if for some reason the output load is lost in the metering circuit, for example. Each section has 8 22Meg 2W carbon composite resistors and they wrap 180 degrees around the center. there are delrin stock going down the center where the connecting post are to join these 180 degree sections together for support. In the past to my knowledge there has not been an issue of this kind, even if the unit is arching out, etc. But recently after the techs replaced a few of these strings due to what they say was signs of aging with heat spots, they now have these sections blowing apart and adjacent sections that were not replaced, when ever the spark gap gets a collapse. We know there is external issues with the metering circuit and that will be fixed later, but it shouldn't be causing this. Is it possible these halves are suppose to be phased magnetically so that when impulsed current appears in the string they null out physical...

May 04, 2014 109 Replies

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DecadentLinuxUserNumeroUno 12 years ago

On Sat, 10 May 2014 18:59:59 -0700 (PDT), Bill Sloman Gave us:

Your pathetic horseshit is beyond funny!

I recommend "James Gang, Live At Carnegie Hall".

Start with the first track.

BRL!

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DecadentLinuxUserNumeroUno 12 years ago

On Sun, 11 May 2014 07:16:29 -0700 (PDT), Bill Sloman Gave us:

You're a joke.

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YD 12 years ago

Odd that. Mine wraps just fine when I tell it to.

- YD.

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DecadentLinuxUserNumeroUno 12 years ago

On Sun, 11 May 2014 23:13:33 -0700 (PDT), Bill Sloman Gave us:

Did you learn some new words, Billy?

Damnit, Janet!

I meant to aim that cannon at you. Better luck next time.

Guess I have to remember to chalk first.

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DecadentLinuxUserNumeroUno 12 years ago

On Sun, 11 May 2014 23:13:33 -0700 (PDT), Bill Sloman Gave us:

Is your name Zimmerman?

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DecadentLinuxUserNumeroUno 12 years ago

On Sun, 11 May 2014 23:13:30 -0300, YD Gave us:

Talking to your computer, are you. :-)

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Bill Sloman 12 years ago

"Graphic detail" is a cliche. I don't waste original phrases around here.

Bill Sloman, Sydney

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YD 12 years ago

Just figuratively. Actually it's clicking an item on a menu. But you knew that.

- YD.

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Fred Bartoli 12 years ago

formatting link

gives, at standard conditions

Air: 24.36 mW/(m.K) SF6: 11.627 mW/(m.K)

Thanks, Fred.

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George Herold 12 years ago

Nice, Thanks Fred. About a factor of two... Of course there is most likely convection happening too. And that might be a whole different story.

George H.

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