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how to separate ground potential

Started by Saul Bernstein October 16, 2008
Hi,

thanks for your kind answers so far. To answer your question: The PCB won't 
be connected to anything other than the 4kV and the 220V mains.

Saul


"John Fields" <jfields@austininstruments.com> schrieb im Newsbeitrag 
news:3ftef4hjuggm6qgerbrq9snn6i4b7fvem7@4ax.com...
> On Thu, 16 Oct 2008 08:40:17 +0200, "Saul Bernstein" > <jiffylube@freenet.de> wrote: > >>Hi, >> >>I have to design a printed circuit board for a high-voltage environment. >>Hence, the "ground potential" of the board has to be on 4 kV. Du to the >>fact >>that the absolute potential values don't matter, one could say that the 2 >>kV >>are virtually my ground potential. The problem arises by reason of the >>power >>supply. I have to power my board with 5 V and for the mains adapter ground >>is really 0 V. >> >>Can someone think of a possibility to supply my board with a mains adapter >>(AC/DC 220V/5V) and translate between the two ground reference potentials? > > --- > Will the PCB be connected to anything other than the high voltage supply > positive and the 220V mains? > > JF
Paul Keinanen wrote:

> On Fri, 17 Oct 2008 07:36:36 +0100, IanM <Invalid@totally.invalid> > wrote: > > >>Paul Keinanen wrote: >> >>>On Thu, 16 Oct 2008 17:49:25 -0400, legg <legg@nospam.magma.ca> wrote: >>> >>> >>> >>>>You haven't indicated the voltage and power requirement for this >>>>housekeeping supply. >>>> >>>>At lower power levels, some simple self-constructed solutions are >>>>possible. >>> >>> >>>At very low power levels, just send optical power up on an optical >>>fiber and the data down on an other fiber. >>> >>>This system is used on some high voltage measurement instruments >>>hanging on an overhead high voltage line. >>> >>>Paul >>> >> >>Thats an interesting technique I've been hearing a little about lately. >> >>Whats state of the art for power over fiber? How big a laser does one >>need for how many mW at the remote end? Got any good links? > > > Do a Google search such as > > "optically powered" "current transformer" > > should give some useful links. > > For instance > http://homepage.ufp.pt/alobo/page8/page5/files/IEEE%20PPT%20Conf2001_2.pdf > describe a 300 mW laser at 810 nm and a photocell efficiency of 40 %, > so you would get about 100 mW of usable DC power for the sensor and > the optical transmitter to send back the information. > > Paul >
Thanks Paul. 6V (open circuit) GaAs photovoltaic diode. It looks like there would be no particular problem getting 15 mA at 3.3 V for a microcontroller or whatever. I suspect that it would be out of the price range of the average hobbyist but if one is building Van Der Graph generators or similar it might be justifiable. Its a far cry from two minature PM DC motors coupled shaft to shaft with a couple of feet of Perspex rod in between :-) Ian.
Saul Bernstein wrote:
> > thanks for your kind answers so far. To answer your question: > The PCB won't be connected to anything other than the 4kV and > the 220V mains.
Please do not top-post. Your answer belongs after (or intermixed with) the quoted material to which you reply, after snipping all irrelevant material. See the following links: <http://www.catb.org/~esr/faqs/smart-questions.html> <http://www.caliburn.nl/topposting.html> <http://www.netmeister.org/news/learn2quote.html> <http://cfaj.freeshell.org/google/> (taming google) <http://members.fortunecity.com/nnqweb/> (newusers) -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: <http://cbfalconer.home.att.net> Try the download section.
On Oct 15, 11:40=A0pm, "Saul Bernstein" <jiffyl...@freenet.de> wrote:
> Hi, > > I have to design a printed circuit board for a high-voltage environment. > Hence, the "ground potential" of the board has to be on 4 kV. Du to the f=
act
> that the absolute potential values don't matter, one could say that the 2=
kV
> are virtually my ground potential. The problem arises by reason of the po=
wer
> supply. I have to power my board with 5 V and for the mains adapter groun=
d
> is really 0 V. > > Can someone think of a possibility to supply my board with a mains adapte=
r
> (AC/DC 220V/5V) and translate between the two ground reference potentials=
? How about a battery? At low powers and bad efficiencies, transformers to handle a 4KV isolation is fairly easy. At bigger power levels or efficiencies above 50% it gets harder fast. What does this PCB have to do? How much power etc? Does the PCB live inside a shield? At low powers, the simplest design is to use an "air core" transformer with the primary and secondaries tuned and loose coupling between then because of the large clearance. The down side is that this tends to radiate a lot of RF at your operating frequency.
On Fri, 17 Oct 2008 14:24:43 +0100, IanM <Invalid@totally.invalid>
wrote:

> >Its a far cry from two minature PM DC motors coupled shaft to shaft with >a couple of feet of Perspex rod in between :-)
At least this mechanical system can be scaled to quite large power levels :-) http://en.wikipedia.org/wiki/Lyon-Moutiers_DC_transmission_scheme Other low power isolated power transmission systems include feeding acoustic vibrations into an isolating rod or using radio frequency power transmission (after all the isolation distance required is only a few meters). Paul
Paul Keinanen wrote:
> IanM <Invalid@totally.invalid> wrote: > >> Its a far cry from two minature PM DC motors coupled shaft to >> shaft with a couple of feet of Perspex rod in between :-) > > At least this mechanical system can be scaled to quite large > power levels :-) > > http://en.wikipedia.org/wiki/Lyon-Moutiers_DC_transmission_scheme
Highly sensitive to dust, thus needing continuous maintenance, IMO. -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: <http://cbfalconer.home.att.net> Try the download section.
On Wed, 15 Oct 2008 23:40:17 -0700, Saul Bernstein wrote
(in article <48f6e1b8$0$6569$9b4e6d93@newsspool4.arcor-online.net>):

> Hi, > > I have to design a printed circuit board for a high-voltage environment. > Hence, the "ground potential" of the board has to be on 4 kV. Du to the fact > that the absolute potential values don't matter, one could say that the 2 kV > are virtually my ground potential. The problem arises by reason of the power > supply. I have to power my board with 5 V and for the mains adapter ground > is really 0 V. > > Can someone think of a possibility to supply my board with a mains adapter > (AC/DC 220V/5V) and translate between the two ground reference potentials? > > Thank you > > Saul
How much power do you need? How about a couple of solar cells and a halogen work light? -- Charlie Springer
Saul Bernstein wrote:

> Hi, > > I have to design a printed circuit board for a high-voltage > environment. Hence, the "ground potential" of the board has to be on 4 > kV. Du to the fact that the absolute potential values don't matter, one > could say that the 2 kV are virtually my ground potential. The problem > arises by reason of the power supply. I have to power my board with 5 V > and for the mains adapter ground is really 0 V. > > Can someone think of a possibility to supply my board with a mains > adapter (AC/DC 220V/5V) and translate between the two ground reference > potentials? > > Thank you > > Saul
Yes this sort of thing can be done but you really should know what you are doing in the high voltage areas when doing projects like this. Some of the systems I work with have rails of 132kV DC (in the MW region) and this takes very special handling and checking from the design through the implementation to maintenance planning before we build such systems. As many of the professional engineers here who would know this stuff and know of the dangers it is hardly surprising you are not getting much help without knowing your level of experience. It is an area that is at such a level that if you have to ask then you shouldn't be doing this without adequate oversight and supervision. The professionals will want to know that you have that in place and by asking here it is obvious that you probably haven't and it would be criminal for them to offer a solution. -- ******************************************************************** Paul E. Bennett...............<email://Paul_E.Bennett@topmail.co.uk> Forth based HIDECS Consultancy Mob: +44 (0)7811-639972 Tel: +44 (0)1235-811095 Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
On Oct 15, 11:40=A0pm, "Saul Bernstein" <jiffyl...@freenet.de> wrote:
> > I have to design a printed circuit board for a high-voltage environment. > Hence, the "ground potential" of the board has to be on 4 kV.
This is the same sort of problem as electron microscopes (and even microwave ovens) have in driving the filament. The easy solution is to box up a 6V battery and regulate down to 5V. The commercial solution is a custom-made, tested, transformer that safely holds off 4 kV. It's likely to be potted (embedded in a blob of tar or silicone). You don't want any of the 4kV parts outside a shielded and interlocked enclosure, of course...
On Sat, 18 Oct 2008 10:42:42 -0700, whit3rd wrote
(in article 
<7f356697-56f9-4e2b-9da1-60e1b27044cd@26g2000hsk.googlegroups.com>):

>> I have to design a printed circuit board for a high-voltage environment. >> Hence, the "ground potential" of the board has to be on 4 kV. > > This is the same sort of problem as electron microscopes (and > even microwave ovens) have in driving the filament. The easy > solution is to box up a 6V battery and regulate down to 5V. > The commercial solution is a custom-made, tested, transformer > that safely holds off 4 kV. It's likely to be potted (embedded > in a blob of tar or silicone). > > You don't want any of the 4kV parts outside a shielded and > interlocked enclosure, of course...
There are neon signs all over the place, often within reach of drunks ........ ? -- Charlie Springer