John Rumm wrote:

> Andy Burns wrote:
>
>> I notice that BSI are clamping down on access to PDFs and requiring DRM
>> plug-ins now ...
>
> only if you have access that allows downloads... (most library subs only
> officially give "view only" access)

Looks like they haven't converted all their files to include DRM yet?

A couple of months ago, I used the "unofficial" method to download amendment1
for BS7671 (not BS7671 including amendment1 which is not made available) it was
unreadable in sumatraPDF and would only work in AcrobatReader with the FileOpen
plugin installed.

<https://plugin.fileopen.com>

I've just tried opening that same file again today, and it has expired, so
AcrobatReader bounces you here

<https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>

On 04/05/2022 06:43, Andy Burns wrote:
> John Rumm wrote:
>
>> Andy Burns wrote:
>>
>>> I notice that BSI are clamping down on access to PDFs and requiring DRM
>>> plug-ins now ...
>>
>> only if you have access that allows downloads... (most library subs
>> only officially give "view only" access)
>
> Looks like they haven't converted all their files to include DRM yet?
>
> A couple of months ago, I used the "unofficial" method to download
> amendment1 for BS7671 (not BS7671 including amendment1 which is not made
> available) it was unreadable in sumatraPDF and would only work in
> AcrobatReader with the FileOpen plugin installed.
>
> <https://plugin.fileopen.com>
>
> I've just tried opening that same file again today, and it has expired,
> so AcrobatReader bounces you here
>
> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>

ok interesting, not seen that... I have the AFDD doc for example, and
can't see any requirement to open with a DRM plugin (opens in old
version of acrobat, foxit reader, and in a browser internal PDF reader).

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

John Rumm wrote:

> On 04/05/2022 06:43, Andy Burns wrote:
>
>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
>
> ok interesting, not seen that... I have the AFDD doc for example, and can't see
> any requirement to open with a DRM plugin (opens in old version of acrobat,
> foxit reader, and in a browser internal PDF reader).

I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it last night
they're identical, neither are protected, but their newer ones (e.g. the BS7671
amd1) are protected.

On 04/05/2022 10:36, Andy Burns wrote:
> John Rumm wrote:
>
>> On 04/05/2022 06:43, Andy Burns wrote:
>>
>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
>>
>>
>> ok interesting, not seen that... I have the AFDD doc for example, and
>> can't see any requirement to open with a DRM plugin (opens in old
>> version of acrobat, foxit reader, and in a browser internal PDF reader).
>
> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it
> last night they're identical, neither are protected, but their newer
> ones (e.g. the BS7671 amd1) are protected.

I've long railed against the way Parliament has in effect outsourced so
much "tertiary legislation" to the BSI and given them a licence to
charge whatever they want for access to it. Sadly little interest in DIY
these days among the political class.

--
Robin
reply-to address is (intended to be) valid

On 04/05/2022 11:29, Robin wrote:
> On 04/05/2022 10:36, Andy Burns wrote:
>> John Rumm wrote:
>>
>>> On 04/05/2022 06:43, Andy Burns wrote:
>>>
>>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
>>>
>>>
>>>
>>> ok interesting, not seen that... I have the AFDD doc for example, and
>>> can't see any requirement to open with a DRM plugin (opens in old
>>> version of acrobat, foxit reader, and in a browser internal PDF reader).
>>
>> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it
>> last night they're identical, neither are protected, but their newer
>> ones (e.g. the BS7671 amd1) are protected.
>
> I've long railed against the way Parliament has in effect outsourced so
> much "tertiary legislation" to the BSI and given them a licence to
> charge whatever they want for access to it. Sadly little interest in DIY
> these days among the political class.

I agree, and the documentarian is not cheap. Some years ago a colleague
bought an ISO standard from the Polish equivalent of BSI at a much lower
cost that from UK BSI. It had the identical French and English sections.

On 04/05/2022 13:01, Fredxx wrote:
> On 04/05/2022 11:29, Robin wrote:
>> On 04/05/2022 10:36, Andy Burns wrote:
>>> John Rumm wrote:
>>>
>>>> On 04/05/2022 06:43, Andy Burns wrote:
>>>>
>>>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
>>>>
>>>>
>>>>
>>>>
>>>> ok interesting, not seen that... I have the AFDD doc for example,
>>>> and can't see any requirement to open with a DRM plugin (opens in
>>>> old version of acrobat, foxit reader, and in a browser internal PDF
>>>> reader).
>>>
>>> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it
>>> last night they're identical, neither are protected, but their newer
>>> ones (e.g. the BS7671 amd1) are protected.
>>
>> I've long railed against the way Parliament has in effect outsourced
>> so much "tertiary legislation" to the BSI and given them a licence to
>> charge whatever they want for access to it. Sadly little interest in
>> DIY these days among the political class.
>
> I agree, and the documentarian is not cheap. Some years ago a colleague
> bought an ISO standard from the Polish equivalent of BSI at a much lower
> cost that from UK BSI. It had the identical French and English sections.

And the committees that write the standards (my father was on a couple
and chaired one for a while) are made up of people employed by and at
the cost of companies in the relevant industries.

In article <t4u6df$kra$1@dont-email.me>, Steve Walker
<steve@walker-family.me.uk> wrote:
> On 04/05/2022 13:01, Fredxx wrote:
> > On 04/05/2022 11:29, Robin wrote:
> >> On 04/05/2022 10:36, Andy Burns wrote:
> >>> John Rumm wrote:
> >>>
> >>>> On 04/05/2022 06:43, Andy Burns wrote:
> >>>>
> >>>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> ok interesting, not seen that... I have the AFDD doc for example,
> >>>> and can't see any requirement to open with a DRM plugin (opens in
> >>>> old version of acrobat, foxit reader, and in a browser internal PDF
> >>>> reader).
> >>>
> >>> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it
> >>> last night they're identical, neither are protected, but their newer
> >>> ones (e.g. the BS7671 amd1) are protected.
> >>
> >> I've long railed against the way Parliament has in effect outsourced
> >> so much "tertiary legislation" to the BSI and given them a licence to
> >> charge whatever they want for access to it. Sadly little interest in
> >> DIY these days among the political class.
> >
> > I agree, and the documentarian is not cheap. Some years ago a colleague
> > bought an ISO standard from the Polish equivalent of BSI at a much
> > lower cost that from UK BSI. It had the identical French and English
> > sections.

> And the committees that write the standards (my father was on a couple
> and chaired one for a while) are made up of people employed by and at
> the cost of companies in the relevant industries.

Certainly the commitee that I served on had only one third of
manufacturers. Another third were potential users and the remaining lot was
assorted 'intersted parties'.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 04/05/2022 10:36, Andy Burns wrote:
> John Rumm wrote:
>
>> On 04/05/2022 06:43, Andy Burns wrote:
>>
>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
>>
>>
>> ok interesting, not seen that... I have the AFDD doc for example, and
>> can't see any requirement to open with a DRM plugin (opens in old
>> version of acrobat, foxit reader, and in a browser internal PDF reader).
>
> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it
> last night they're identical, neither are protected, but their newer
> ones (e.g. the BS7671 amd1) are protected.

Are the documents still accessible on devices like phones etc, and are
they compatible with screen readers?

(i.e. do they fall foul of not meeting requirements under disability
legislation)

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On 04/05/2022 17:18, charles wrote:
> In article <t4u6df$kra$1@dont-email.me>, Steve Walker
> <steve@walker-family.me.uk> wrote:
>> On 04/05/2022 13:01, Fredxx wrote:
>>> On 04/05/2022 11:29, Robin wrote:
>>>> On 04/05/2022 10:36, Andy Burns wrote:
>>>>> John Rumm wrote:
>>>>>
>>>>>> On 04/05/2022 06:43, Andy Burns wrote:
>>>>>>
>>>>>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ok interesting, not seen that... I have the AFDD doc for example,
>>>>>> and can't see any requirement to open with a DRM plugin (opens in
>>>>>> old version of acrobat, foxit reader, and in a browser internal PDF
>>>>>> reader).
>>>>>
>>>>> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded it
>>>>> last night they're identical, neither are protected, but their newer
>>>>> ones (e.g. the BS7671 amd1) are protected.
>>>>
>>>> I've long railed against the way Parliament has in effect outsourced
>>>> so much "tertiary legislation" to the BSI and given them a licence to
>>>> charge whatever they want for access to it. Sadly little interest in
>>>> DIY these days among the political class.
>>>
>>> I agree, and the documentarian is not cheap. Some years ago a colleague
>>> bought an ISO standard from the Polish equivalent of BSI at a much
>>> lower cost that from UK BSI. It had the identical French and English
>>> sections.
>
>> And the committees that write the standards (my father was on a couple
>> and chaired one for a while) are made up of people employed by and at
>> the cost of companies in the relevant industries.
>
> Certainly the commitee that I served on had only one third of
> manufacturers. Another third were potential users and the remaining lot was
> assorted 'intersted parties'.

But none paid by the BSI! The standards are written by third parties,
but the BSI charge prices that are prohibitively high for individuals
and small businesses.

In article <t4uddr$k01$2@dont-email.me>, Steve Walker
<steve@walker-family.me.uk> wrote:
> On 04/05/2022 17:18, charles wrote:
> > In article <t4u6df$kra$1@dont-email.me>, Steve Walker
> > <steve@walker-family.me.uk> wrote:
> >> On 04/05/2022 13:01, Fredxx wrote:
> >>> On 04/05/2022 11:29, Robin wrote:
> >>>> On 04/05/2022 10:36, Andy Burns wrote:
> >>>>> John Rumm wrote:
> >>>>>
> >>>>>> On 04/05/2022 06:43, Andy Burns wrote:
> >>>>>>
> >>>>>>> <https://www.bsigroup.com/en-GB/topics/supporting-our-clients-and-content-partners/access-denied>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> ok interesting, not seen that... I have the AFDD doc for example,
> >>>>>> and can't see any requirement to open with a DRM plugin (opens in
> >>>>>> old version of acrobat, foxit reader, and in a browser internal
> >>>>>> PDF reader).
> >>>>>
> >>>>> I have kept the AFDD doc I downloaded in 2019 and I re-downloaded
> >>>>> it last night they're identical, neither are protected, but their
> >>>>> newer ones (e.g. the BS7671 amd1) are protected.
> >>>>
> >>>> I've long railed against the way Parliament has in effect outsourced
> >>>> so much "tertiary legislation" to the BSI and given them a licence
> >>>> to charge whatever they want for access to it. Sadly little interest
> >>>> in DIY these days among the political class.
> >>>
> >>> I agree, and the documentarian is not cheap. Some years ago a
> >>> colleague bought an ISO standard from the Polish equivalent of BSI at
> >>> a much lower cost that from UK BSI. It had the identical French and
> >>> English sections.
> >
> >> And the committees that write the standards (my father was on a couple
> >> and chaired one for a while) are made up of people employed by and at
> >> the cost of companies in the relevant industries.
> >
> > Certainly the commitee that I served on had only one third of
> > manufacturers. Another third were potential users and the remaining lot
> > was assorted 'intersted parties'.

> But none paid by the BSI!

there was a BSI person present, but, since this was around 50 years ago, I
am not sure, but I'm sure he chaired the meeting. The BSI also provided the
premises in which we met.

> The standards are written by third parties, but the BSI charge prices
> that are prohibitively high for individuals and small businesses.

The standard was proposed by one party, objected to by another, the BSI put
it all together.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 04/05/2022 18:33, Steve Walker wrote:

>
> But none paid by the BSI! The standards are written by third parties,
> but the BSI charge prices that are prohibitively high for individuals
> and small businesses.
>

They run as a business (despite their monopoly positionm). The CEO's
pay and bonuses last year came to £m1.2.

--
Robin
reply-to address is (intended to be) valid

John Rumm wrote:

> Are the documents still accessible on devices like phones etc

They provide windows and mac acrobat plugins
and iThing and android viewers (sounds like they are standalone rather than
plugins, not tried)
no mention of Linux

> and are they
> compatible with screen readers?
> (i.e. do they fall foul of not meeting requirements under disability legislation)

No mention

<https://plugin.fileopen.com/faq>

On 04/05/2022 19:35, Andy Burns wrote:
> John Rumm wrote:
>
>> Are the documents still accessible on devices like phones etc
>
> They provide windows and mac acrobat plugins
> and iThing and android viewers (sounds like they are standalone rather
> than plugins, not tried)
> no mention of Linux

From the FAQ

"Which operating systems are supported?

The FileOpen Client will work on Windows 7 or later, Mac OSX 10.9 or
above, iOS, Android and Linux."

>> and are they compatible with screen readers? (i.e. do they fall foul
>> of not meeting requirements under disability legislation)
>
> No mention
>
> <https://plugin.fileopen.com/faq>

No mention but it might have a fighting chance since it seems to use
adobe reader to do the rendering, and that can support assistive
technologies.

Still most things are compatible with my screen reader OCR in the worst
case! :-)

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On 05/05/2022 19:11, John Rumm wrote:
> On 04/05/2022 19:35, Andy Burns wrote:
>> John Rumm wrote:
>>
>>> Are the documents still accessible on devices like phones etc
>>
>> They provide windows and mac acrobat plugins
>> and iThing and android viewers (sounds like they are standalone rather
>> than plugins, not tried)
>> no mention of Linux
>
> From the FAQ
>
> "Which operating systems are supported?
>
> The FileOpen Client will work on Windows 7 or later, Mac OSX 10.9 or
> above, iOS, Android and Linux."
>
>>> and are they compatible with screen readers? (i.e. do they fall foul
>>> of not meeting requirements under disability legislation)
>>
>> No mention
>>
>> <https://plugin.fileopen.com/faq>
>
> No mention but it might have a fighting chance since it seems to use
> adobe reader to do the rendering, and that can support assistive
> technologies.
>
> Still most things are compatible with my screen reader OCR in the worst
> case! :-)
>

I have seen mention that there is the option to print one copy of a
FileOpen protected PDF. Does that work on yours? (and to a PDF printer
driver?)

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

John Rumm wrote:

> I have seen mention that there is the option to print one copy of a FileOpen
> protected PDF. Does that work on yours? (and to a PDF printer driver?)

From acrobat print is disabled, from within firefox, it will print a single
page to pdf not the whole doc, you get the UI of their viewer printed into the
output, and it looks like you can only print page #1

On 03/05/2022 23:16, Andy Burns wrote:
> John Rumm wrote:
>
>> Vir Campestris wrote:
>>
>>> I'd be interested to read something on the theory, and why they need
>>> a CPU with any grunt in it at all. After all they're just signal
>>> processing a 50Hz waveform. It's not exactly RF... My google fu has
>>> failed me, and I can't see anything that says _how_ they do it.
>>
>> Probably because the "how" is proprietary and where the money is to be
>> made for the early vendors (before they have been copied and
>> commoditised at least!)
>>
>> (Also the waveforms they will interested in will be up into RF - not
>> just 50Hz)
>
> From previous curiosity I happened to have the relevant BS doc saved,
> here is an example current/voltage waveform they gave, but no clues how
> closely it needs to fit that envelope to cause a "trip"
>
> <http://andyburns.uk/misc/afdd-example-waveform.png>

Green is current and magenta voltage? Thanks.

TNP, I too think they'd do an FFT - but this is a 50Hz carrier with
harmonics not more than an order of magnitude above. At those
frequencies FFTs aren't very compute intensive. We need proper ARM cores
to run at audio - but we're a thousand times higher frequencies.

Andy

On 06/05/2022 14:06, Vir Campestris wrote:
> On 03/05/2022 23:16, Andy Burns wrote:
>> John Rumm wrote:
>>
>>> Vir Campestris wrote:
>>>
>>>> I'd be interested to read something on the theory, and why they need
>>>> a CPU with any grunt in it at all. After all they're just signal
>>>> processing a 50Hz waveform. It's not exactly RF... My google fu has
>>>> failed me, and I can't see anything that says _how_ they do it.
>>>
>>> Probably because the "how" is proprietary and where the money is to
>>> be made for the early vendors (before they have been copied and
>>> commoditised at least!)
>>>
>>> (Also the waveforms they will interested in will be up into RF - not
>>> just 50Hz)
>>
>>  From previous curiosity I happened to have the relevant BS doc saved,
>> here is an example current/voltage waveform they gave, but no clues
>> how closely it needs to fit that envelope to cause a "trip"
>>
>> <http://andyburns.uk/misc/afdd-example-waveform.png>
>
> Green is current and magenta voltage? Thanks.
>
> TNP, I too think they'd do an FFT - but this is a 50Hz carrier with
> harmonics not more than an order of magnitude above. At those
> frequencies FFTs aren't very compute intensive. We need proper ARM cores
> to run at audio - but we're a thousand times higher frequencies.
>

BEAMA and many academics share the view that they need to look at kHz or
MHz signatures

--
Robin
reply-to address is (intended to be) valid

On 06/05/2022 15:41, Robin wrote:
> BEAMA and many academics share the view that they need to look at kHz or
> MHz signatures

:O

Do you have a link?

Andy

On Friday, 6 May 2022 at 14:06:54 UTC+1, Vir Campestris wrote:
> On 03/05/2022 23:16, Andy Burns wrote:
> > John Rumm wrote:
> >
> >> Vir Campestris wrote:
> >>
> >>> I'd be interested to read something on the theory, and why they need
> >>> a CPU with any grunt in it at all. After all they're just signal
> >>> processing a 50Hz waveform. It's not exactly RF... My google fu has
> >>> failed me, and I can't see anything that says _how_ they do it.
> >>
> >> Probably because the "how" is proprietary and where the money is to be
> >> made for the early vendors (before they have been copied and
> >> commoditised at least!)
> >>
> >> (Also the waveforms they will interested in will be up into RF - not
> >> just 50Hz)
> >
> > From previous curiosity I happened to have the relevant BS doc saved,
> > here is an example current/voltage waveform they gave, but no clues how
> > closely it needs to fit that envelope to cause a "trip"
> >
> > <http://andyburns.uk/misc/afdd-example-waveform.png>
> Green is current and magenta voltage? Thanks.
>
> TNP, I too think they'd do an FFT - but this is a 50Hz carrier with
> harmonics not more than an order of magnitude above. At those
> frequencies FFTs aren't very compute intensive. We need proper ARM cores
> to run at audio - but we're a thousand times higher frequencies.
>
> Andy

The components of arc waveforms are a long way above 500Hz. Despite all that I can see how to put together an entirely compute-free AFDD. Just like early RCDs, which were little more than a differential transformer, such an AFDD might not be as thorough in its protection as a computerised one.

On 06/05/2022 21:02, Vir Campestris wrote:
> On 06/05/2022 15:41, Robin wrote:
>> BEAMA and many academics share the view that they need to look at kHz
>> or MHz signatures
>
> :O
>
> Do you have a link?
>
> Andy

Yes.

Do you have a search engine (Google, Bing, DuckDuckGo or whatever)?

--
Robin
reply-to address is (intended to be) valid

On 06/05/2022 21:11, Animal wrote:
> On Friday, 6 May 2022 at 14:06:54 UTC+1, Vir Campestris wrote:
>> On 03/05/2022 23:16, Andy Burns wrote:
>>> John Rumm wrote:
>>>
>>>> Vir Campestris wrote:
>>>>
>>>>> I'd be interested to read something on the theory, and why
>>>>> they need a CPU with any grunt in it at all. After all
>>>>> they're just signal processing a 50Hz waveform. It's not
>>>>> exactly RF... My google fu has failed me, and I can't see
>>>>> anything that says _how_ they do it.
>>>>
>>>> Probably because the "how" is proprietary and where the money
>>>> is to be made for the early vendors (before they have been
>>>> copied and commoditised at least!)
>>>>
>>>> (Also the waveforms they will interested in will be up into RF
>>>> - not just 50Hz)
>>>
>>> From previous curiosity I happened to have the relevant BS doc
>>> saved, here is an example current/voltage waveform they gave, but
>>> no clues how closely it needs to fit that envelope to cause a
>>> "trip"
>>>
>>> <http://andyburns.uk/misc/afdd-example-waveform.png>
>> Green is current and magenta voltage? Thanks.
>>
>> TNP, I too think they'd do an FFT - but this is a 50Hz carrier
>> with harmonics not more than an order of magnitude above. At those
>> frequencies FFTs aren't very compute intensive. We need proper ARM
>> cores to run at audio - but we're a thousand times higher
>> frequencies.
>>
>> Andy
>
> The components of arc waveforms are a long way above 500Hz. Despite
> all that I can see how to put together an entirely compute-free AFDD.
> Just like early RCDs, which were little more than a differential
> transformer, such an AFDD might not be as thorough in its protection
> as a computerised one.

I expect is not getting it to trip on an arc, but getting it to not trip
on the wrong sort of arc.

e.g. you don't want it tripping on switch bounce, brush arcing, or
switch start lamp starting. Probably not on a circuit feeding an arc
light or an arc welder.

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On 06/05/2022 23:00, John Rumm wrote:
> On 06/05/2022 21:11, Animal wrote:
>> On Friday, 6 May 2022 at 14:06:54 UTC+1, Vir Campestris wrote:
>>> On 03/05/2022 23:16, Andy Burns wrote:
>>>> John Rumm wrote:
>>>>
>>>>> Vir Campestris wrote:
>>>>>
>>>>>> I'd be interested to read something on the theory, and why
>>>>>> they need a CPU with any grunt in it at all. After all
>>>>>> they're just signal processing a 50Hz waveform. It's not
>>>>>> exactly RF... My google fu has failed me, and I can't see
>>>>>> anything that says _how_ they do it.
>>>>>
>>>>> Probably because the "how" is proprietary and where the money
>>>>> is to be made for the early vendors (before they have been
>>>>> copied and commoditised at least!)
>>>>>
>>>>> (Also the waveforms they will interested in will be up into RF
>>>>> - not just 50Hz)
>>>>
>>>> From previous curiosity I happened to have the relevant BS doc
>>>> saved, here is an example current/voltage waveform they gave, but
>>>> no clues how closely it needs to fit that envelope to cause a
>>>> "trip"
>>>>
>>>> <http://andyburns.uk/misc/afdd-example-waveform.png>
>>> Green is current and magenta voltage? Thanks.
>>>
>>> TNP, I too think they'd do an FFT - but this is a 50Hz carrier
>>> with harmonics not more than an order of magnitude above. At those
>>> frequencies FFTs aren't very compute intensive. We need proper ARM
>>> cores to run at audio - but we're a thousand times higher
>>> frequencies.
>>>
>>> Andy
>>
>> The components of arc waveforms are a long way above 500Hz. Despite
>> all that I can see how to put together an entirely compute-free AFDD.
>> Just like early RCDs, which were little more than a differential
>> transformer, such an AFDD might not be as thorough in its protection
>> as a computerised one.
>
> I expect is not getting it to trip on an arc, but getting it to not trip
> on the wrong sort of arc.
>
> e.g. you don't want it tripping on switch bounce, brush arcing, or
> switch start lamp starting. Probably not on a circuit feeding an arc
> light or an arc welder.
>

All of which has long left me wondering how they define a standard for
AFDDs /and/ a practicable means of testing manufacturer's products
against it. As for end users, substitution seems the only practicable
test if a faulty AFDD is suspected. Unless of course they are
guaranteed to be free from defect for life - software included :)

--
Robin
reply-to address is (intended to be) valid

On Friday, 6 May 2022 at 23:00:14 UTC+1, John Rumm wrote:
> On 06/05/2022 21:11, Animal wrote:
> > On Friday, 6 May 2022 at 14:06:54 UTC+1, Vir Campestris wrote:
> >> On 03/05/2022 23:16, Andy Burns wrote:
> >>> John Rumm wrote:
> >>>
> >>>> Vir Campestris wrote:
> >>>>
> >>>>> I'd be interested to read something on the theory, and why
> >>>>> they need a CPU with any grunt in it at all. After all
> >>>>> they're just signal processing a 50Hz waveform. It's not
> >>>>> exactly RF... My google fu has failed me, and I can't see
> >>>>> anything that says _how_ they do it.
> >>>>
> >>>> Probably because the "how" is proprietary and where the money
> >>>> is to be made for the early vendors (before they have been
> >>>> copied and commoditised at least!)
> >>>>
> >>>> (Also the waveforms they will interested in will be up into RF
> >>>> - not just 50Hz)
> >>>
> >>> From previous curiosity I happened to have the relevant BS doc
> >>> saved, here is an example current/voltage waveform they gave, but
> >>> no clues how closely it needs to fit that envelope to cause a
> >>> "trip"
> >>>
> >>> <http://andyburns.uk/misc/afdd-example-waveform.png>
> >> Green is current and magenta voltage? Thanks.
> >>
> >> TNP, I too think they'd do an FFT - but this is a 50Hz carrier
> >> with harmonics not more than an order of magnitude above. At those
> >> frequencies FFTs aren't very compute intensive. We need proper ARM
> >> cores to run at audio - but we're a thousand times higher
> >> frequencies.
> >>
> >> Andy
> >
> > The components of arc waveforms are a long way above 500Hz. Despite
> > all that I can see how to put together an entirely compute-free AFDD.
> > Just like early RCDs, which were little more than a differential
> > transformer, such an AFDD might not be as thorough in its protection
> > as a computerised one.
> I expect is not getting it to trip on an arc, but getting it to not trip
> on the wrong sort of arc.
>
> e.g. you don't want it tripping on switch bounce, brush arcing, or
> switch start lamp starting. Probably not on a circuit feeding an arc
> light or an arc welder.

Capacitor to harvest the hf content, rectify, current limit, big cap so it doesnt respond to half a second of arcing, magnetic trip. Simple stuff. The only load I can think of where it might be on shaky ground is the arc welder.

Arc light lol. Even if one did use one in 2022, they don't draw lots of hf current. I used to use them. No-one does now.

On Saturday, 7 May 2022 at 09:22:40 UTC+1, Robin wrote:
> On 06/05/2022 23:00, John Rumm wrote:
> > On 06/05/2022 21:11, Animal wrote:
> >> On Friday, 6 May 2022 at 14:06:54 UTC+1, Vir Campestris wrote:
> >>> On 03/05/2022 23:16, Andy Burns wrote:
> >>>> John Rumm wrote:
> >>>>
> >>>>> Vir Campestris wrote:
> >>>>>
> >>>>>> I'd be interested to read something on the theory, and why
> >>>>>> they need a CPU with any grunt in it at all. After all
> >>>>>> they're just signal processing a 50Hz waveform. It's not
> >>>>>> exactly RF... My google fu has failed me, and I can't see
> >>>>>> anything that says _how_ they do it.
> >>>>>
> >>>>> Probably because the "how" is proprietary and where the money
> >>>>> is to be made for the early vendors (before they have been
> >>>>> copied and commoditised at least!)
> >>>>>
> >>>>> (Also the waveforms they will interested in will be up into RF
> >>>>> - not just 50Hz)
> >>>>
> >>>> From previous curiosity I happened to have the relevant BS doc
> >>>> saved, here is an example current/voltage waveform they gave, but
> >>>> no clues how closely it needs to fit that envelope to cause a
> >>>> "trip"
> >>>>
> >>>> <http://andyburns.uk/misc/afdd-example-waveform.png>
> >>> Green is current and magenta voltage? Thanks.
> >>>
> >>> TNP, I too think they'd do an FFT - but this is a 50Hz carrier
> >>> with harmonics not more than an order of magnitude above. At those
> >>> frequencies FFTs aren't very compute intensive. We need proper ARM
> >>> cores to run at audio - but we're a thousand times higher
> >>> frequencies.
> >>>
> >>> Andy
> >>
> >> The components of arc waveforms are a long way above 500Hz. Despite
> >> all that I can see how to put together an entirely compute-free AFDD.
> >> Just like early RCDs, which were little more than a differential
> >> transformer, such an AFDD might not be as thorough in its protection
> >> as a computerised one.
> >
> > I expect is not getting it to trip on an arc, but getting it to not trip
> > on the wrong sort of arc.
> >
> > e.g. you don't want it tripping on switch bounce, brush arcing, or
> > switch start lamp starting. Probably not on a circuit feeding an arc
> > light or an arc welder.
> >
> All of which has long left me wondering how they define a standard for
> AFDDs /and/ a practicable means of testing manufacturer's products
> against it.

That's easy. The manufacturer makes them as complex & expensive as possible, determines the reuslting specs & uses that as the new standard. Anyone else's goods that don't match it fail.

> As for end users, substitution seems the only practicable
> test if a faulty AFDD is suspected. Unless of course they are
> guaranteed to be free from defect for life - software included :)

I expect testers will show up. It's not to hard to simulate an arc - or even create a real one, not that anyone would now.

Animal wrote:

> Capacitor to harvest the hf content, rectify, current limit, big cap so it doesnt respond to half a second of arcing, magnetic trip. Simple stuff. The only load I can think of where it might be on shaky ground is the arc welder.
>
> Arc light lol. Even if one did use one in 2022, they don't draw lots of hf current. I used to use them. No-one does now.

Have you watched any of the videos where John Ward or David Savery cobbled
together rigs to generate arcs and found it remarkably difficult to get AFDDs to
trip? The manufacturers seem to demonstrate them using a "magic pelicase" rig.