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Re: CDC upstream end config
Adding to Fernando's last comment about using cables outside recommended
limits:
If there is no other recourse, this is of course an option. However,
"Testing" does not just mean checking to see if a cable segment in a
controlled situation holds off a given voltage. There are issues related
environment (temp, humidity, dirt, etc), which connectors are used and how
they are attached, grounding schemes, etc. These are only a few issues
which need to be considered beyond the question about what safety factors
are needed before use.
Therefore, alternatives should be investigated in detail before even
considering non-standard alternatives.
My two cents. Elton.
Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite # 16
Newport News, VA 23606
elton@jlab.org
(757) 269-7625
(757) 269-6331 fax
On Mon, 8 Dec 2008, Fernando J. Barbosa wrote:
> Hi Tim,
>
> My comments follow:
>
> Tim Whitlatch wrote:
> > Hello All,
> >
> > Per our video conference this morning, the following was discussed;
> >
> > Gary will continue to manufacture a 24 place upstream plate with
> > proper geometries from "geometry C". this will give room for
> > simulating worst case spacial considerations for assy. He will pursue
> > the original type setup with 5.5 inch long cables max.
> >
> > As a backup, Gary will manufacture an offset plate with the 24 holes
> > to take the stress off the conductive rubber sleeve (per SLAVA)
> >
> > Fernando, Gary followed up on the coax cables you suggested. They all
> > seem to come without an outside insulating jacket. Is it possible to
> > use these cables by keeping the braided shield at ground? Also, is it
> > possible to use cable that is not rated for our high voltage by doing
> > some tests?
> Of the two suggestions to check the cable routing, one of the coaxes
> should have a jacket but the semi-rigid cable should have an aluminized
> jacket. In this case, an insulating sleeve/jacket needs to be installed
> and there are various types offered by multiple companies. I suggest
> FEP, if available in the required diameter. The shield needs to be at HV
> and in normal operation the potential difference between the shield and
> the inner conductor is zero. However, if a straw wire is disabled, the
> full HV potential will be present and the cable needs to conform to
> these requirements.
>
> Cables can certainly be tested at higher voltages than the rated
> operating voltage specified by the manufacturer but that's a safety
> issue. I strongly recommend against overlooking the manufacturer's
> safety specifications.
>
> Regards,
> Fernando
>
>
> >
> > I will pursue with Tom Carstens from Hall B about connector leaks on
> > their drift chambers.
> >
> > Yves will look at getting some extension pcbs made for testing Slava's
> > ides per layout on 9-29-08. Can we get a connector made directly onto
> > the HV board that would plug into this?
> >
> > Thanks for your time,
> >
> > Tim
> >
> >
> >
> >
>