Hi Bert,
Thanks for all of the info; appreciated. Looked at getting some BTDP. After
much research I can get it, but only in bulk, so I have decided to go with
the high voltage transformer oil. I will degas it under vacuum for 24
hours. I will then fill the repaired capacitor allowing an expansion space,
so not quite to the top. Once it has been filled I will further degas under
an Argon atmosphere. I do not expect to be able to rely on the repaired
capacitor being the original voltage rating of 50kV; be good if it's 30kV.
Thanks!
Paul
On Sun, Apr 7, 2019 at 3:52 AM Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hi Paul,
>
> Thanks - that info was a big help.
>
> BTDP is Maxwell's abbreviation for benzyltoluene/diphenylethane, a
> mixture of benzyltoluene (CAS 27776-01-8, 60%) and diphenylethane (CAS
> 612-00-0, 40%) by molecular weight. BTDP was a low-flammability
> low-viscosity alternative to PCB's that was introduced in the 1980's for
> high-voltage capacitors. It absorbs hydrogen gas (which is liberated
> during partial discharges/corona under oil) better than mineral oils,
> and it has a significantly higher static dielectric constant than
> mineral oil. Commercially-available formulations that have a similar
> mixture included Jarylec C100, and Nisseki SAS-40E, or SAS-60E.
>
> I don't know these are readily available to private customers. So... if
> you can't get any of the above dielectric fluids, substitute mineral oil
> and hope for the best. :)
>
> Could you please let us know the results of your repair. Other folks on
> the Pupman list may also have pulse caps with damaged cases.
>
> And, good luck!
>
> Bert
>
>
> Paul McGlen wrote:
> > Hi Bert,
> >
> > Thanks for the response.
> >
> > This is the information that I have:
> > It's a Maxwell (now General Atomic - model 37330, using their proprietary
> > "oil". Impregnant: BTDP
> >
> > Regards
> > Paul
> >
> > On Mon, Apr 1, 2019 at 10:04 PM Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx
> >
> > wrote:
> >
> >> Hi Paul,
> >>
> >> If you can provide links to images of your capacitors, especially the
> >> face-plate, label, or stamped info, or if you can provide manufacturer
> >> info and model number, there is a possibility that we can identify the
> >> type of dielectric fluid. Was "Atomic Research" the manufacturer or
> >> perhaps the application they came from?
> >>
> >> As Jim Lux indicated, a large variety of capacitor dielectric fluids and
> >> blends have been used in HV capacitors over the last half century. Many
> >> of these fluids were proprietary and not readily available to a casual
> >> hobbyist and others (such as PCB's) are no longer available. And some
> >> benzine-based "aromatic" fluids were more volatile than others, so its
> >> possible that the capacitor rolls may have partially dried out.
> >>
> >> The easiest fix is to try adding mineral oil and resealing it. before
> >> resealing, drawing a partial vacuum for 24 hours or so may help to
> >> remove entrapped air inside the rolls if they've partially dried out.
> >> Finally, if the cap is packaged in a cylindrical container, remember to
> >> leave a small air bubble in the cap to provide room for expansion of the
> >> capacitor rolls especially if you plan to use the cap for Tesla Coil
> >> operation. The repaired cap should be usable, but you may need to derate
> >> its operating voltage...
> >>
> >> Bert
> >>
> >> Paul McGlen wrote:
> >>> Hi All,
> >>> I recently acquired some Atomic Research Pulse Capacitors. They are
> 50kV
> >>> and 100nF, however, one of them was damaged and the oil has leaked out,
> >> so
> >>> I need to replace this. Does anyone know what this oil is and where I
> can
> >>> get it. If not can I replace it with high voltage transformer oil?
> >>>
> >>> Cheers.
> >>> _______________________________________________
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> >>> Tesla@xxxxxxxxxxxxxxxxxx
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> >>>
> >>>
> >>
> >>
> >>
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>
>
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