[OpenTRV-dev] OT: Voltage drops
Stuart Poulton
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Tue Jun 11 14:29:16 BST 2013
Ok.
You should still design for 3 phase voltages. You should consider what
would happen if the whole board were to become live.
I'd be going with getting something like this installed
http://www.shmmetershop.co.uk/DAB13000-3-Phase-N-ABB-DeltaPlus-MID-Approved-Multifunction-meter-with-Pulse-Output.html
Again, I still havn't heard what the perceived benefit of 'accurate
voltage' measurement is ? How are you planning to measure current ?
Stuart
On 11/06/13 14:26, Bo Herrmannsen wrote:
> oh.. no one board for each pahse.... i have 3 sockets over the fuse
> box.. clearly marked with what phase it goes to.... not excatly legal,
> but that part i can live with...
>
> /bo
>
> 2013/6/11 Stuart Poulton <EMAIL ADDRESS HIDDEN
> <mailto:EMAIL ADDRESS HIDDEN>>
>
> Ok.
>
> Don't forget PCB design criteria change with 3 phase. You may find
> this of use
>
> http://ww1.microchip.com/downloads/en/DeviceDoc/51723a.pdf
>
> Stuart
>
> On 11/06/13 14:18, Bo Herrmannsen wrote:
>
> yep, 3phase is standard here (almost) 3phases+neutral+earth
>
> 2013/6/11 Stuart Poulton <EMAIL ADDRESS HIDDEN
> <mailto:EMAIL ADDRESS HIDDEN> <mailto:EMAIL ADDRESS HIDDEN
> <mailto:EMAIL ADDRESS HIDDEN>>>
>
> Bo,
>
> Can you clarify, are you talking about voltage and current
> measurement on a 3 phase supply ?
>
> Thanks
>
> Stuart
>
>
> On 11/06/13 14:07, Bo Herrmannsen wrote:
>
> hmm... i think you are right.. its the phase shift
> part that
> will benefit most from what i'm doing
>
>
> i will also agree to that 0-100A is rather a hughe
> step... for
> me thats far beyound what i need, i can draw a max of
> 16A amps
> on each of the 3phases i got in the fuse box
>
> /bo
>
>
> 2013/6/11 Kevin Wood <EMAIL ADDRESS HIDDEN
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>
> Indeed. Looking at the openenergy design, it's the
> current
> monitoring side
> that would be the largest source of error due to
> the fact
> that it
> lacks
> resolution, especially at low power levels. A
> couple of
> current ranges
> rather than trying to do 0-100A in one range would
> help
> there (I think
> someone's proposed a design to do just that
> somewhere).
>
> Measuring mains voltage through an off-the-shelf
> step-down
> transformer
> with a purely resistive load takes us back into the
> comfort zone
> of most
> constructors as far as safety goes and I can't
> believe it
> introduces much
> of an error if calibrated. Maybe a bit of phase
> shift and
> flattening of
> the top of the waveform if the transformer is a
> bit close to
> saturation?..
> Not sure. Will have to have a play with that.
>
> Kevin
>
> > I think the question here is what are the
> benefits of
> 'almost error
> > free' mains voltage measurements ?
> >
> > Then compare to the risks, biggest being death,
> or fire.
> >
> > Stuart
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