[OpenTRV-dev] OT: Voltage drops
Bo Herrmannsen
EMAIL ADDRESS HIDDEN
Tue Jun 11 15:03:36 BST 2013
oh forgot about current... if i was to use the method about messuring
voltage and current i would messure the current with a clamp on each
phase... in fact i allready have them installed...
feel a bit like a fool now that the pulse out might do the trick
only need to figure a sketch for it... still having a bit of work to do on
my water meter that also has a pulse out
2013/6/11 Stuart Poulton <EMAIL ADDRESS HIDDEN>
> 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<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<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
>> <mailto:EMAIL ADDRESS HIDDEN**com <EMAIL ADDRESS HIDDEN>>
>> <mailto:EMAIL ADDRESS HIDDEN**com<EMAIL ADDRESS HIDDEN>
>> <mailto:EMAIL ADDRESS HIDDEN**com <EMAIL ADDRESS HIDDEN>>>
>> <mailto:EMAIL ADDRESS HIDDEN**com<EMAIL ADDRESS HIDDEN>
>> <mailto:EMAIL ADDRESS HIDDEN**com <EMAIL ADDRESS HIDDEN>>
>> <mailto:EMAIL ADDRESS HIDDEN**com<EMAIL ADDRESS HIDDEN>
>> <mailto:EMAIL ADDRESS HIDDEN**com <EMAIL ADDRESS HIDDEN>
>> >>>>
>>
>> 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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