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Re: rotary question

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Bob,

At 03:04 AM 2/26/2001 +0000, you wrote:
>above forula is right this is only 140 BPS. If this is the case I must
>be really hammering my caps,They are getting warm.
>Can someone tell me how to work this out please before I fry all my
>caps. Killed a string of caps today. I think this was due to the inside
>primary connection coming off rather  than the break rate, I ran the
>coil up, no sparks,  thought it was out of tune tried again and noticed
>smoke and flames coming from the cap. Opps, only damaged one cap in the
>middle of the string closest to the connections. some photos  of the
>fried cap will appear on hot streamer soon I hope.I must warn you they
>don't make pleasant viewing  :-(( well not to me anyway.

The photos are at:


I would worry that the drain resistors are laying directly on the cap cases
as in picure:


The cap cases cannot stand off much voltage and corona may form between the
resistor and the cap case if the underlying plates are of opposite
polarity.  Perhaps bending the resistors up a bit off the cases would help
prevent corrona damage and possible arcing.

You caps seem to be getting pretty hot as shown by the rough "corregation"
or rippling in the bodies as shown at:


The caps almost have a tiger strip pattern espicially when they blow and
soot is blown into the stripes as in:


As the caps heated, the dielectric started to melt and arcing began in the
internal floating layer at the edges.  Since they were hot and going down,
the self healing was no help and they catostophically arced in the center
as shown in:


So the current is too high.  You need more strings,  Probably 4 times more!
 your caps are listed as good at:


I have seen these caps and they are fairly good with a dissipation only
slightly less than the Panasonics.

You can ohm out and measure the value of the remaining caps to check for
hidden damage to the others.  Sometimes they read as shorted or the value
is way off if there is internal damage.



>bob golding