Logging mains voltage: Arduino or Raspberry Pi?

[newshound]

For reasons I won't bore you with, I'm interested in building a cheap,
simple data logger to monitor mains voltage, ideally two channels (live
to earth and neutral to earth). In the dim and distant past I have
designed and built such things more or less from scratch, but surely
someone has already done this.

I havn't used either Arduino or Pi before, but I assume one or other
would be the obvious starting point.

However ATM google isn't giving me a strong lead. Thoughts?

[The Nomad]

A quick google came up with:

<https://openenergymonitor.org/forum-archive/node/58.html>

<https://circuitdigest.com/microcontroller-projects/arduino-ac-voltmeter>

<https://www.briandorey.com/post/arduino-mains-voltage-and-current-
logging>

Avpx

--
And the child had a permanently runny nose and ought to be provided with
a handkerchief or, failing that, a cork.
(Lords and Ladies)
12:45:01 up 13 days, 23:13, 15 users, load average: 1.66, 1.05, 0.76

[Theo]

newshound <news...@stevejqr.plus.com> wrote:
> For reasons I won't bore you with, I'm interested in building a cheap,
> simple data logger to monitor mains voltage, ideally two channels (live
> to earth and neutral to earth). In the dim and distant past I have
> designed and built such things more or less from scratch, but surely
> someone has already done this.

What do you want to do with the data when you've measured it?

Theo

[newshound]

On 12/04/2018 12:51, The Nomad wrote:
> On Thu, 12 Apr 2018 12:37:06 +0100, newshound
> <news...@stevejqr.plus.com> wrote:
>
>> For reasons I won't bore you with, I'm interested in building a cheap,
>> simple data logger to monitor mains voltage, ideally two channels (live
>> to earth and neutral to earth). In the dim and distant past I have
>> designed and built such things more or less from scratch, but surely
>> someone has already done this.
>>
>> I havn't used either Arduino or Pi before, but I assume one or other
>> would be the obvious starting point.
>>
>> However ATM google isn't giving me a strong lead. Thoughts?
>
> A quick google came up with:
>
> <https://openenergymonitor.org/forum-archive/node/58.html>
>
> <https://circuitdigest.com/microcontroller-projects/arduino-ac-voltmeter>
>
> <https://www.briandorey.com/post/arduino-mains-voltage-and-current-
> logging>
>
> Avpx
>

Thanks, that second one looks like a good basis.

[Martin Brown]

Unless you are wedded to doing it with an RPi it might be easier to use
something that comes with ADCs as standard. ARM evaluation board maybe.

Learning curve for getting anything to work is a bit steeper. eg.

https://uk.rs-online.com/web/p/processor-microcontroller-development-kits/1501738/

I have one of the STM ones which ISTR are about £20.

--
Regards,
Martin Brown

[newshound]

I'm trying to see if there are overvoltage transients on a farm site,
and/or what the neutral is doing. Slow, rather than fast transients. I
recognise that the arduino analogue inputs are multiplexed.

So, I want to collect data for a week or so, then pop it into Excel to
see if anything is going on.

Would you go for Arduino rather than adding an ADC to a Pi?

[Brian Gaff]

I was just wondering in what way you want to log it, RMS peak or cycle
differences, leakage or impedance of earth/Neutral etc.
Brian

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[Brian Gaff]

I was just thinking, if I were trying to do this, I'd be needing to measure
live to neutral on a small load, and the resistance of the earth to neutral
or maybe anything that is being generated between them. anything else will
be seen by the other measurement. However its important to run a load
realistically during the times of monitoring and also switching any loads
that could be connected to see how it responds. I've measured lots of spikes
on mains when very little is actually running, but when things are running
particularly resistive loads like heaters or cookers, the spikes are fewer,
making me think much of it is just generated by some other reactive loads
switching.
Not able to do this now of course, but look on a scope at unfiltered and
unloaded mains and its a wonder that it works!

Brian

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"newshound" <news...@stevejqr.plus.com> wrote in message

news:X_OdneZF2sE7wVLH...@brightview.co.uk...

[Theo]

newshound <news...@stevejqr.plus.com> wrote:
> I'm trying to see if there are overvoltage transients on a farm site,
> and/or what the neutral is doing. Slow, rather than fast transients. I
> recognise that the arduino analogue inputs are multiplexed.
>
> So, I want to collect data for a week or so, then pop it into Excel to
> see if anything is going on.

OK, so how do you intend to get the data from the widget into Excel? Plug
into a USB port? Write to an SD card? Wifi? Email? Internet?

How reliable does it need to be? Can you cope if it reboots occasionally?

How slow is a slow transient?

> Would you go for Arduino rather than adding an ADC to a Pi?

It depends what you want to do.

Theo

[Andrew Gabriel]

In article <BcadncQjGbB_2VLH...@brightview.co.uk>,

Funny, I've just built some hardware to do this on a Pi
for a presentation and demo I'm doing later this month.
However, the object was to demonstrate using an ADC on a
Pi rather than specifically to measure the mains voltage,
although I thought it might be fun to record mains voltage.

As has been said, the Pi doesn't have native ADC built-in,
so you would need to add on ADC's.
However, another significant factors would be which of these
platforms you have familiarity with, and if having a linux
OS there would be useful for the project, or not.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

[John Rumm]

On 12/04/2018 12:37, newshound wrote:

Thinking outside the box a bit, many line interactive UPSs come with
voltage logging and can be connected via USB.

--
Cheers,

John.

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

[Michael Chare]

On 12/04/2018 12:51, The Nomad wrote:

> On Thu, 12 Apr 2018 12:37:06 +0100, newshound
> <news...@stevejqr.plus.com> wrote:
>
>> For reasons I won't bore you with, I'm interested in building a cheap,
>> simple data logger to monitor mains voltage, ideally two channels (live
>> to earth and neutral to earth). In the dim and distant past I have
>> designed and built such things more or less from scratch, but surely
>> someone has already done this.
>>
>> I havn't used either Arduino or Pi before, but I assume one or other
>> would be the obvious starting point.
>>
>> However ATM google isn't giving me a strong lead. Thoughts?
>
> A quick google came up with:
>
> <https://openenergymonitor.org/forum-archive/node/58.html>
>

I have an openenergy Arduino. It sends data to a Raspberry Pi running
Openenergy software. For a while I was using a public Openenergy
server. Readings are recorded every second. I record live to neutral
voltage. To record other voltages I would need an irregular 13 amp socket.

If I am away from home in the winter I can see whether my boiler has
been running.

--
Michael Chare

[tony sayer]

In article <9Cu*yO...@news.chiark.greenend.org.uk>, Theo <theom+news@chi
ark.greenend.org.uk> scribeth thus

More or less any old APC UPS wll tell you what the voltage is over time
least the few i have do that show you over and under volts...
--
Tony Sayer

[Halmyre]

Won't the capacitor smooth out any transients you might want to observe?

[newshound]

I am looking for transients longer than maybe a second or so. Obviously,
might need to experiment with capacitors a bit.

[newshound]

On 12/04/2018 17:58, John Rumm wrote:
> On 12/04/2018 12:37, newshound wrote:
>> For reasons I won't bore you with, I'm interested in building a cheap,
>> simple data logger to monitor mains voltage, ideally two channels (live
>> to earth and neutral to earth). In the dim and distant past I have
>> designed and built such things more or less from scratch, but surely
>> someone has already done this.
>>
>> I havn't used either Arduino or Pi before, but I assume one or other
>> would be the obvious starting point.
>>
>> However ATM google isn't giving me a strong lead. Thoughts?
>
> Thinking outside the box a bit, many line interactive UPSs come with
> voltage logging and can be connected via USB.
>

Others have made that point. I don't have one and don't really think I
need one. I think I should be able to "DIY" a solution which would also
serve as an introduction to this new kit: I've been thinking for a while
that it would be nice to have a portable data logger that I could use to
monitor the heating system, etc.

I have an old PicoLog system somewhere that came in handy when
diagnosing a combi boiler problem, but of course that had to be hooked
up to a rumning netbook so it was all a bit cumbersome.

[newshound]

I've not touched either platform before, one of my reasons I'm
interested in the views of those who have.

I converted an old desktop into a Ubuntu box so that I could have a
play, and I've also got a Mint stick that I have used occasionally. I'm
not particularly bothered about getting into Linux, but I'd do it if I
had a project that needed it. I havn't done any serious coding for more
than 30 years, but I imagine I could pick it up without too much
difficulty (especially now that it's easy to find examples on the net).

[John Rumm]

On 13/04/2018 10:36, newshound wrote:
> On 12/04/2018 17:58, John Rumm wrote:
>> On 12/04/2018 12:37, newshound wrote:
>>> For reasons I won't bore you with, I'm interested in building a cheap,
>>> simple data logger to monitor mains voltage, ideally two channels (live
>>> to earth and neutral to earth). In the dim and distant past I have
>>> designed and built such things more or less from scratch, but surely
>>> someone has already done this.
>>>
>>> I havn't used either Arduino or Pi before, but I assume one or other
>>> would be the obvious starting point.
>>>
>>> However ATM google isn't giving me a strong lead. Thoughts?
>>
>> Thinking outside the box a bit, many line interactive UPSs come with
>> voltage logging and can be connected via USB.
>>
> Others have made that point. I don't have one and don't really think I
> need one.

Fair enough - just thought I would mention it in case you had one
knocking about and had not thought about it.

> I think I should be able to "DIY" a solution which would also
> serve as an introduction to this new kit: I've been thinking for a while
> that it would be nice to have a portable data logger that I could use to
> monitor the heating system, etc.

A roll your own solution will obviously be more versatile (and probably
fun!)

[The Natural Philosopher]

Hmm. My instinct would be to sample MUCH more frequently than that and
sample AC as well so that you get a really good set of smaples, and then
do any filtering in 'software'

I dunno how long an arduino trakes to do a sample but it cant be that long

Oh. It seems you can sample at up to 9.6Khz...that should do nicley -
and take an RMS value of the waverorm and moving average it out over the
last say one second...and use that to store.

Or uses a shirfter period for more sensitivity to transients

Basically you need a small mains transformer to step down to about 5VAC
or so, then a voltage diveider to set the mean voltage in the middle of
the arduino range, and a pot to scale the output to - say 0-5V
representing up to say 500V peak...


If say you are taking 5khz samples you will need a nmemoiryy buffer of
5000 16 bits (10k of RAM) to store the samples and a further location
to do the running average in.

Well within an arduino I'd say.







--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly

[whisky-dave]

The problem I'd see with an Arduino would be Time in that it;s not very good as a clock but this would only be important if you wanted to know what time an event happend rather than it just happening and being recorded.

[newshound]

Thanks, yes I agree completely about the sampling strategy, but I'd sort
out details once I knew the capability of the device. My point was that
I think I am looking for slowish variations rather than microsecond
transients. (I am trying to find what is killing electric kettle elements).

As you say, small mains transformer, a few resistors and of course a 5
volt Zener on the ADC input.

[newshound]

Yes, I'm not necessarily worried about exact time. Unless I suppose I
want to escalate the results to the distribution company.

[newshound]

On 13/04/2018 11:43, John Rumm wrote:
> On 13/04/2018 10:36, newshound wrote:
>> On 12/04/2018 17:58, John Rumm wrote:
>>> On 12/04/2018 12:37, newshound wrote:
>>>> For reasons I won't bore you with, I'm interested in building a cheap,
>>>> simple data logger to monitor mains voltage, ideally two channels (live
>>>> to earth and neutral to earth). In the dim and distant past I have
>>>> designed and built such things more or less from scratch, but surely
>>>> someone has already done this.
>>>>
>>>> I havn't used either Arduino or Pi before, but I assume one or other
>>>> would be the obvious starting point.
>>>>
>>>> However ATM google isn't giving me a strong lead. Thoughts?
>>>
>>> Thinking outside the box a bit, many line interactive UPSs come with
>>> voltage logging and can be connected via USB.
>>>
>> Others have made that point. I don't have one and don't really think I
>> need one.
>
> Fair enough - just thought I would mention it in case you had one
> knocking about and had not thought about it.
>
>>  I think I should be able to "DIY" a solution which would also
>> serve as an introduction to this new kit: I've been thinking for a while
>> that it would be nice to have a portable data logger that I could use to
>> monitor the heating system, etc.
>
> A roll your own solution will obviously be more versatile (and probably
> fun!)
>

Fun is good :-)

[dennis@home]

You need a simple mains transformer to a few volts and feed it into the
A-D converter on an arduino and do some maths on the samples.
Only a couple of resistors required to set the voltage range to be
within the ADC input range.

A nodeMCU will almost certainly do everything you want including logging
to a remote database.

[whisky-dave]

How often will it sample and what sort levels of spikes and transcients.
And don't forget the ADC can only really 'see' DC voltages.

> Only a couple of resistors required to set the voltage range to be
> within the ADC input range.

doesn't help much though, in fact depending on these spikes you might not 'see' much after reducing it through a transformer and rectifier.

> A nodeMCU will almost certainly do everything you want including logging
> to a remote database.

Problem is dealing with mains AC voltages and having to reduce them first.

[The Natural Philosopher]

My point is, do the low pass filtering in software, though.

A bridge rectifier and smoothing cap is a peak voltage reading abortion
for this: you want to do an RMS average especially for kettle elements.

My solution is less components, but more code.

Code is cheap!

Only issue is doing a square root in binary integers...arduinos don't
have native floating point shit!

>
> As you say, small mains transformer, a few resistors and of course a 5
> volt Zener on the ADC input.

Well i'd just clamp that to the 5V rails.

You will run at a high impedance so no damage dumping the odd mA into
the supply





--
“Some people like to travel by train because it combines the slowness of
a car with the cramped public exposure of 
an airplane.”

Dennis Miller

[whisky-dave]

On Friday, 13 April 2018 15:44:58 UTC+1, The Natural Philosopher wrote:

> > Thanks, yes I agree completely about the sampling strategy, but I'd sort
> > out details once I knew the capability of the device. My point was that
> > I think I am looking for slowish variations rather than microsecond
> > transients. (I am trying to find what is killing electric kettle elements).
>
> My point is, do the low pass filtering in software, though.
>
> A bridge rectifier and smoothing cap is a peak voltage reading abortion
> for this: you want to do an RMS average especially for kettle elements.
>
> My solution is less components, but more code.
>
> Code is cheap!

Depending on how long it takes you.
The idea device would just be a pen holder that respondened to changes in the voltage a bit like an old chart recorder and I'm still not sure how you'll detect what's blowing a kettle elimante I wouldn't have thought they'd be suseptable to transients.

>
> Only issue is doing a square root in binary integers...arduinos don't
> have native floating point shit!

I'm still note sure how you'll know what caused teh transcient even after detecting it.

How long will this kettle element be ON for ?

[newshound]

OK, it's not an element in a kettle. It's in a wallpaper stripper, used
as a steam generator. They are typically failing after half a dozen
(separate) 20 minute sessions. They are not being boiled dry, they are
on a timer to prevent that. Oh, and nothing else seems to be blowing. I
*originally* thought it must be a problem with the chemistry of the
local water supply but two separate chemists with long experience are
convinced that this is unlikely.

I just thought that for less than £100 worth of re-useable bits it would
be nice to investigate the electrics.

[newshound]

On 13/04/2018 15:44, The Natural Philosopher wrote:

> On 13/04/18 15:02, newshound wrote:

>
> My point is, do the low pass filtering in software, though.
>
> A bridge rectifier and smoothing cap is a peak voltage reading abortion
> for this: you want to do an RMS average especially for kettle elements.
>
> My solution is less components, but more code.
>
> Code is cheap!
>
> Only issue is doing a square root in binary integers...arduinos don't
> have native floating point shit!
>
>

Let's park that for the moment

>
>
>
>>
>> As you say, small mains transformer, a few resistors and of course a 5
>> volt Zener on the ADC input.
>
> Well i'd just clamp that to the 5V rails.

Clamp what? I'm confused.

[The Natural Philosopher]

On 13/04/18 17:24, newshound wrote:
> On 13/04/2018 15:44, The Natural Philosopher wrote:
>> On 13/04/18 15:02, newshound wrote:
>
>>
>> My point is, do the low pass filtering in software, though.
>>
>> A bridge rectifier and smoothing cap is a peak voltage reading
>> abortion for this: you want to do an RMS average especially for kettle
>> elements.
>>
>> My solution is less components, but more code.
>>
>> Code is cheap!
>>
>> Only issue is doing a square root in binary integers...arduinos don't
>> have native floating point shit!
>>
>>
> Let's park that for the moment
>>
>>
>>
>>>
>>> As you say, small mains transformer, a few resistors and of course a
>>> 5 volt Zener on the ADC input.
>>
>> Well i'd just clamp that to the 5V rails.
>
> Clamp what? I'm confused.

The input.

resistor and reverse biased diode to +5V. If it goes above 5V the diode
clamps it to the suplly rail plus half a volt or so. Standsard technique.


https://i.stack.imgur.com/LfzyT.png

is a perfect example

from a similar app.

https://electronics.stackexchange.com/questions/139215/long-term-effect-of-over-voltage-on-clamping-diodes-and-adc-reference-voltage




--
“A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
“We did this ourselves.”

― Lao Tzu, Tao Te Ching

[Cursitor Doom]

On Thu, 12 Apr 2018 12:37:06 +0100, newshound wrote:

> I havn't used either Arduino or Pi before, but I assume one or other
> would be the obvious starting point.
>
> However ATM google isn't giving me a strong lead. Thoughts?

Arduino, hands-down. Otherwise you're paying about 3 times the price for
a lot of fancy graphics rendering power you will not be needing.
Personally I also much prefer C to Bash.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

[Cursitor Doom]

On Fri, 13 Apr 2018 07:38:11 -0700, whisky-dave wrote:

> Problem is dealing with mains AC voltages and having to reduce them
> first.

Not really. Loads of suitable sub-min mains transformers in every local
recycling site; help yourself for free. Or just a couple of quid new from
China through Ebay.

[The Natural Philosopher]

On 13/04/18 20:45, Cursitor Doom wrote:
> On Fri, 13 Apr 2018 07:38:11 -0700, whisky-dave wrote:
>
>> Problem is dealing with mains AC voltages and having to reduce them
>> first.
>
> Not really. Loads of suitable sub-min mains transformers in every local
> recycling site; help yourself for free. Or just a couple of quid new from
> China through Ebay.
>
>
>

Or 3 and a bit quid from Rapid

https://www.rapidonline.com/vigortronix-vtx-120-003-606-pcb-open-mains-transformer-3va-0-6v-88-3700



--
How fortunate for governments that the people they administer don't think.

Adolf Hitler

[tony sayer]

In article <p7KdnYdNBqNzRU3H...@brightview.co.uk>,
newshound <news...@stevejqr.plus.com> scribeth thus

So let me get this right your trying to find out why a steam wallpaper
stripper is failing?.

I'd ask what make is it ?. Where is it made?

What's the actual specified mains voltage of the element in use for it?

What the local mains voltage as measured over few days sampling and are
you in a rural overhead line fed area or urban underground?

And has the same thing happened to any like for like replacements?...

Finally does it take any RCD trip out when it fails?.
--
Tony Sayer

[dennis@home]

AC is just DC with an offset.

>
>
>> Only a couple of resistors required to set the voltage range to be
>> within the ADC input range.
>
> doesn't help much though, in fact depending on these spikes you might
> not 'see' much after reducing it through a transformer and
> rectifier.

So we have something else you don't know much about.

>
>
>
>> A nodeMCU will almost certainly do everything you want including
>> logging to a remote database.
>
> Problem is dealing with mains AC voltages and having to reduce them
> first.
>

Isolating transformers isolate the mains and reduce them to safe levels.

[dennis@home]

On 13/04/2018 20:38, Cursitor Doom wrote:
> On Thu, 12 Apr 2018 12:37:06 +0100, newshound wrote:
>
>> I havn't used either Arduino or Pi before, but I assume one or other
>> would be the obvious starting point.
>>
>> However ATM google isn't giving me a strong lead. Thoughts?
>
> Arduino, hands-down. Otherwise you're paying about 3 times the price for
> a lot of fancy graphics rendering power you will not be needing.
> Personally I also much prefer C to Bash.
>
>
>

https://learn.openenergymonitor.org/electricity-monitoring/voltage-sensing/measuring-voltage-with-an-acac-power-adapter

[newshound]

On 13/04/2018 18:47, The Natural Philosopher wrote:

> On 13/04/18 17:24, newshound wrote:

>>>>
>>>> As you say, small mains transformer, a few resistors and of course a
>>>> 5 volt Zener on the ADC input.
>>>
>>> Well i'd just clamp that to the 5V rails.
>>
>> Clamp what? I'm confused.
>
> The input.
>
> resistor and reverse biased diode to +5V. If it goes above 5V the diode
> clamps it to the suplly rail plus half a volt or so. Standsard technique.
>
>
> https://i.stack.imgur.com/LfzyT.png
>
> is a perfect example
>
> from a similar app.
>
> https://electronics.stackexchange.com/questions/139215/long-term-effect-of-over-voltage-on-clamping-diodes-and-adc-reference-voltage
>

OK perhaps I am getting my Zeners and Shottkys mixed up, it is a long
time since I actually built anything like that. But that's the principle
I was trying to convey.

[Dave W]

"newshound" <news...@stevejqr.plus.com> wrote in message
news:p7KdnYdNBqNzRU3H...@brightview.co.uk...

It's ridiculous to imagine that mains quality has anything to do with your
wallpaper strippers failing.

Failing in what way? Permanently? Open circuit? Short circuit? Resettably?
What make & model?
--
Dave W

[NY]

"Dave W" <dave...@yahoo.co.uk> wrote in message
news:pash7s$rlq$1...@gioia.aioe.org...

>
> It's ridiculous to imagine that mains quality has anything to do with your
> wallpaper strippers failing.
>
> Failing in what way? Permanently? Open circuit? Short circuit? Resettably?
> What make & model?

If it is failing open or short circuit, that suggests that the element is
"burning out" - that its temperature is rising to a point that it melts and
either breaks or else makes contact with earth. Over-voltage would seem to
be a plausible cause of this. But with a large amount of water around it
(the water that the wallpaper stripper is boiling) and presumably good
conduction from the element wire to the surface and from there to the water,
I'd be surprised if over-voltage would cause *that* much of a temperature
rise.

Sounds an intriguing problem. I'll be interested to hear whether the mains
voltage *is* varying that much, if you manage to get a data logger working.

[The Natural Philosopher]

No: using a zener is a completely different technique. There you aim to
divert extra overvoltage current to ground. The clamp diverts it to the
power supply first.



Shottkys are only necessary to clamp fast transients, also: Ordinary
diodes work OK. Just put a small cap after the resistor.

Like this

http://vps.templar.co.uk/Odds%20and%20Ends/Mains-detector-input-stage.png

[newshound]

Thanks very much, that makes sense now!

[tony sayer]

>>> A nodeMCU will almost certainly do everything you want including
>>> logging to a remote database.
>>
>> Problem is dealing with mains AC voltages and having to reduce them
>> first.
>>
>


>Isolating transformers isolate the mains and reduce them to safe levels.
>
>

Care to expand of that statement Dennis?..
--
Tony Sayer

[jrwal...@gmail.com]

On Friday, 13 April 2018 20:45:16 UTC+1, Cursitor Doom wrote:
> On Fri, 13 Apr 2018 07:38:11 -0700, whisky-dave wrote:
>
> > Problem is dealing with mains AC voltages and having to reduce them
> > first.
>
> Not really. Loads of suitable sub-min mains transformers in every local
> recycling site; help yourself for free. Or just a couple of quid new from
> China through Ebay.
>

Most small mains transformers are run very close to core saturation, so
any large transients are likely to be clamped by the transformer. This
could be overcome by putting a resistor in series with the transformer
primary so that it is running at a small fraction of mains voltage.
Have a load resistor on the secondary may improve the performance as well.

John

[The Natural Philosopher]

On 14/04/18 13:44, jrwal...@gmail.com wrote:
> On Friday, 13 April 2018 20:45:16 UTC+1, Cursitor Doom wrote:
>> On Fri, 13 Apr 2018 07:38:11 -0700, whisky-dave wrote:
>>
>>> Problem is dealing with mains AC voltages and having to reduce them
>>> first.
>>
>> Not really. Loads of suitable sub-min mains transformers in every local
>> recycling site; help yourself for free. Or just a couple of quid new from
>> China through Ebay.
>>
> Most small mains transformers are run very close to core saturation, so
> any large transients are likely to be clamped by the transformer.

Oh dear. A pseudo authoritative statement from someone who doesnt know
the difference between voltage and current.

This
> could be overcome by putting a resistor in series with the transformer
> primary so that it is running at a small fraction of mains voltage.
> Have a load resistor on the secondary may improve the performance as well.
>

Oh dear. Soemone who doesnt understand inductance either.


> John
>


--
In todays liberal progressive conflict-free education system, everyone
gets full Marx.

[jrwal...@gmail.com]

On Saturday, 14 April 2018 14:42:10 UTC+1, The Natural Philosopher wrote:

> > Most small mains transformers are run very close to core saturation, so
> > any large transients are likely to be clamped by the transformer.
>
> Oh dear. A pseudo authoritative statement from someone who doesnt know
> the difference between voltage and current.

So do you disagree with my claim that small transformers are usually
run close to core saturation at their rated voltage?

Do you disagree with my expectation that grossly overdriving such a
small transformer (with the transient to be measured) will cause its
output to saturate and give an incorrect measurement result?

> This
> > could be overcome by putting a resistor in series with the transformer
> > primary so that it is running at a small fraction of mains voltage.
> > Have a load resistor on the secondary may improve the performance as well.
>
> Oh dear. Soemone who doesnt understand inductance either.

What exactly do you object to here? A resistively loaded transformer
looks like a resistor (apart from the leakage inductance) so in
conjunction with a series input resistor it will form a reasonable
potential divider thereby moving the operation well away from
saturation.

Please explain.

John

[Roger Hayter]

<jrwal...@gmail.com> wrote:

> On Saturday, 14 April 2018 14:42:10 UTC+1, The Natural Philosopher wrote:
>
> > > Most small mains transformers are run very close to core saturation, so
> > > any large transients are likely to be clamped by the transformer.
> >
> > Oh dear. A pseudo authoritative statement from someone who doesnt know
> > the difference between voltage and current.
>
> So do you disagree with my claim that small transformers are usually
> run close to core saturation at their rated voltage?
>
> Do you disagree with my expectation that grossly overdriving such a
> small transformer (with the transient to be measured) will cause its
> output to saturate and give an incorrect measurement result?

Saturation results from current flow. If the transformer has a high
impedance across the secondary saturation will not happen. (The voltage
output may not be precise for other reasons, but should be good enough
for the sort of transients that are going to affect a heating element.)

>
> > This
> > > could be overcome by putting a resistor in series with the transformer
> > > primary so that it is running at a small fraction of mains voltage.
> > > Have a load resistor on the secondary may improve the performance as well.
> >
> > Oh dear. Soemone who doesnt understand inductance either.
>
> What exactly do you object to here? A resistively loaded transformer
> looks like a resistor (apart from the leakage inductance) so in
> conjunction with a series input resistor it will form a reasonable
> potential divider thereby moving the operation well away from
> saturation.
>
> Please explain.
>
> John

The load resistor will not improve anything. The resistor in series
with the primary will just make accurate voltage measurement impossible
because of the poorly defined and frequency dependent primary impedance
while providing no benefits.

--

Roger Hayter

[The Natural Philosopher]

On 14/04/18 17:28, jrwal...@gmail.com wrote:
> On Saturday, 14 April 2018 14:42:10 UTC+1, The Natural Philosopher wrote:
>
>>> Most small mains transformers are run very close to core saturation, so
>>> any large transients are likely to be clamped by the transformer.
>>
>> Oh dear. A pseudo authoritative statement from someone who doesnt know
>> the difference between voltage and current.
>
> So do you disagree with my claim that small transformers are usually
> run close to core saturation at their rated voltage?
>

Yes

> Do you disagree with my expectation that grossly overdriving such a
> small transformer (with the transient to be measured) will cause its
> output to saturate and give an incorrect measurement result?

Yes.

>
>> This
>>> could be overcome by putting a resistor in series with the transformer
>>> primary so that it is running at a small fraction of mains voltage.
>>> Have a load resistor on the secondary may improve the performance as well.
>>
>> Oh dear. Soemone who doesnt understand inductance either.
>
> What exactly do you object to here? A resistively loaded transformer
> looks like a resistor (apart from the leakage inductance) so in
> conjunction with a series input resistor it will form a reasonable
> potential divider thereby moving the operation well away from
> saturation.
>
> Please explain.

I am not here to teach you basic electronics when you think you know it
all already

>
> John

[The Natural Philosopher]

I admire your patience

[dennis@home]

What's to explain? they isolate the mains unlike autotransformers or
some other ways to drop mains voltage.
You aren't going to get a sever shock from a 6V isolating transformer
like you could from a potential divider using resistors.

[newshound]

On 13/04/2018 21:14, tony sayer wrote:

>
>
> So let me get this right your trying to find out why a steam wallpaper
> stripper is failing?.
>
> I'd ask what make is it ?. Where is it made?
>

Modern Earlex, China I expect. 40 year old Earlex, UK I expect.

> What's the actual specified mains voltage of the element in use for it?

220-240 volt

>
> What the local mains voltage as measured over few days sampling

Today, it was 250. Sampling over a few days: THAT'S WHY I WANT A DATA LOGGER

and are
> you in a rural overhead line fed area or urban underground?

As I said earlier, it's rural on overhead lines

>
> And has the same thing happened to any like for like replacements?...

Half a dozen

>
> Finally does it take any RCD trip out when it fails?.

Sometimes but not always. They are failing open circuit, some but not
all fail a megger test.

[Johnny B Good]

An effective way to avoid saturation issues when monitoring for
excessively high voltage excursions is to wire up an identical pair with
their 240v primaries in series and their low voltage (6 or 7 vac?)
secondaries in parallel (in phase current aiding) so as to help maintain
voltage balance between the primaries. Not only will this allow for 100%
excursions beyond the nominal 240vac supply, it should also allow high
frequency transients to be registered without molestation by saturation
effects. However, unless the transformers incorporate a 'grounded' inter
winding screen, high frequency transients can couple capacitively into
the secondary circuit, effectively magnifying their prominence.

If this is just a temporary setup, you can use a PC or laptop to record
the waveform using an audio recording application. Unless you need to
detect extremely high frequency transients, you can choose an 8 or 16 bit
mono sampling rate of 8 or 16 or 22.05 KHz to save disk space if planning
on logging for more than 12 hours worth (Heads Up! 24 hours in 16 bit
stereo at a 44.1KHz sample rate produces a 7GB file! DAMHIK, IJK).

If your main interest is checking for extreme voltage excursions rather
than high voltage spikes. adjust the recording level on the 50Hz
fundamental to -10dB FSD otherwise choose -20dB FSD if you're looking for
high voltage spikes (sub millisecond transients). A -10dB setting allows
you to see overvolting events just in excess of +200% and a -20dB setting
will let you identify spikes as large as 2.4KV without clipping (assuming
the transformer assembly can deal with such spikes).

A quick 'n' dirty way to check whether there were any 'events' worth
zooming in on, is to ask the audio app to calculate a normalisation
factor for the whole period. A normalisation factor of 9dB on a recording
level of -10dB FSD represents a 12.2% voltage boost. OTOH, a
normalisation boost value of 9.172dB represents a 10% overvolting event
on a -10dB recorded level.

HTH & GL!

--
Johnny B Good

[charles]

In article <15sAC.925276$oi5.9...@fx43.am4>,

a 6v transformer is just a transformer. Isolating transformers do just that
_ they isolate - mains level voltage on the output. Used to be an
essential workshop item when dealing withn live cahssis equipment.

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

[charles]

In article <BJmdnWyzVf5FxU_H...@brightview.co.uk>, newshound

ask your supply co to install a voltage logger.

[dennis@home]

On 14/04/2018 21:12, charles wrote:
8<

> a 6v transformer is just a transformer. Isolating transformers do just that
> _ they isolate - mains level voltage on the output. Used to be an
> essential workshop item when dealing withn live cahssis equipment.
>

Not all transformers are isolating!
Why do you suppose I said an isolating transformer rather than an auto
transformer or any other type with a single coil?

[jrwal...@gmail.com]

On Saturday, 14 April 2018 19:29:43 UTC+1, The Natural Philosopher wrote:

The OP is convinced that slow voltage surges are the problem not
fast high-voltage transients. However, this is just an
assumption - there might be fast transients causing insulation
breakdown. Nobody actually knows.

Therefore it would make sense to try and achieve a reasonable
bandwidth if it can be done with little extra effort.

It might be something completely different such as corrosion of the
elements.

Its an interesting problem. I will have a rummage around for a
suitable transformer and make some measurements and report back
in a few days.

John

[Roger Hayter]

Not all, but nearly all! Except for special applications for
autotransformers, most applications require not only isolation but an
insulation resistance tested to some insulation resistance standards,
if only to avoid killing people who touch the secondary circuit and/or
tripping RCDs when the secondary circuit is permanently or transiently
connected to earth. Reference to an "isolating transformer" tends to
imply one used *only* for isolation with a one to one ratio of turns.


--

Roger Hayter

[jrwal...@gmail.com]

On Saturday, 14 April 2018 21:03:15 UTC+1, Johnny B Good wrote:

> An effective way to avoid saturation issues when monitoring for
> excessively high voltage excursions is to wire up an identical pair with
> their 240v primaries in series and their low voltage (6 or 7 vac?)
> secondaries in parallel (in phase current aiding) so as to help maintain
> voltage balance between the primaries. Not only will this allow for 100%
> excursions beyond the nominal 240vac supply, it should also allow high
> frequency transients to be registered without molestation by saturation
> effects. However, unless the transformers incorporate a 'grounded' inter
> winding screen, high frequency transients can couple capacitively into
> the secondary circuit, effectively magnifying their prominence.

A very good approach if two identical transformers are available.

John

[Roger Hayter]

Just to generalise, and by no means to accuse the OP, the commonest
cause of submerged element failure is probably allowing the water level
to get too low, or possibly displaced sideways if the vessel is not kept
horizontal.


--

Roger Hayter

[Roger Hayter]

FAOD, I should have said nearly all *mains* transformers. There are of
course other kinds.


--

Roger Hayter

[Dave Liquorice]

On Sat, 14 Apr 2018 21:13:38 +0100, charles wrote:

> ask your supply co to install a voltage logger.

Just report the "high" voltage, 250 is only 3 short of the permitted
maximum. The DNO for here jumps pretty damn quickly at reports of
wide voltage variation and/or approaching the limits.

If they do install a logger you don't get to see the data.

High voltage will shorten the life incandescant bulbs quite a bit. We
used to get through a bulb every week or two. Bought a UPS plugged it
in it went straight into voltage reduction mode. Measured voltage,
250 ish, rang DNO, engineer at door two hours later, transformer
tapping adjusted next or the day after, bulb consumption fell
noticabley...

I wouldn't expect a 1? 2? kW water heating element to be as sensitive
to voltage as light bulbs unless it's really cheap and nasty. Or made
such that 240 is the max rather than nominal voltage...

--
Cheers
Dave.

[The Natural Philosopher]

On 14/04/18 21:03, Johnny B Good wrote:
> An effective way to avoid saturation issues

THERE ARE NO SATURATION ISSUES UNTIL CURRENT IS DRAWN

WE ARE NOT DRAWING POWER

--
“It is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.”

Thomas Sowell

[The Natural Philosopher]

THis is like renewable energy.

Solving nonexistent problems in the most expensive and complicated way
possible

It's a CRAP approach

>
> John

[dennis@home]

You can say what you like now, but this is a DIY group and some people
won't know what an isolating transformer does or why to use one. Only a
fool expects everyone in a public audience to understand what they say.
Don't give out advice on dangerous stuff unless you make it clear.

Its the same with the advice for 12V supplies people give out, there are
12V supplies that are isolated from the mains but there are some that
aren't and you really don't want the ones that aren't for "projects".
Its hard to tell on ebay/amazon what is and isn't live so I tend not to
buy them when cpc is just as cheap.

[Roger Hayter]

The Natural Philosopher <t...@invalid.invalid> wrote:

> On 14/04/18 21:03, Johnny B Good wrote:
> > An effective way to avoid saturation issues
>
> THERE ARE NO SATURATION ISSUES UNTIL CURRENT IS DRAWN
>
> WE ARE NOT DRAWING POWER

Absolutely. The only reason for using a transformer capable of
supplying significant power is to obtain one with proper mains voltage
insulation. Otherwise any small signal 50:1 transformer with a suitable
low frequency bandwidth would do the job.


--

Roger Hayter

[newshound]

This is one of the mysteries, there are a couple of incandescent bulbs
and AFAIK they are not prone to failure. These are 2.3 kW heaters. As an
alternative to logging data, I suppose I could knock up a diac/triac
"dimmer" to drop the power by (say) 10%.

[Fredxx]

I'm with Dave here. As long as the unit doesn't become dry I wouldn't
expect it to be sensitive on voltage. Methinks a failing batch.

The fact incandescent bulbs can cope with the higher voltage just
confirms these thoughts.

It is possible your DVM reads high. Some are very poor at measuring rms
voltage.

[newshound]

On 14/04/2018 23:42, Roger Hayter wrote:

You are both making reasonable points. Roger, I don't *think* we are
suffering from low water level or tilting, but this is something that I
can't be absolutely certain about. John, I don't *think* it is fast
transients causing insulation failure because then I would be expecting
it to "blow" other stuff like fluorescent lights, phone chargers, the
electronics of the washing machine, etc. But I could be wrong. I
originally thought it must be something in the local water chemistry.
Seeing 250 volts on my single measurement makes me more inclined to
think it is worth doing some logging.

[newshound]

This one read 240V at home. But I will try again with the Robin PSC/loop
tester which is probably more accurate.

[Johnny B Good]

On Sun, 15 Apr 2018 10:17:43 +0100, Roger Hayter wrote:

> The Natural Philosopher <t...@invalid.invalid> wrote:
>
>> On 14/04/18 21:03, Johnny B Good wrote:
>> > An effective way to avoid saturation issues
>>
>> THERE ARE NO SATURATION ISSUES UNTIL CURRENT IS DRAWN

Which statement is total and utter bollocks. :-)

>>
>> WE ARE NOT DRAWING POWER

Essentially true in this case but totally beside the point.

>
> Absolutely. The only reason for using a transformer capable of
> supplying significant power is to obtain one with proper mains voltage
> insulation. Otherwise any small signal 50:1 transformer with a suitable
> low frequency bandwidth would do the job.

Wow! Here's me thinking that it's only TNP that doesn't properly
understand basic electrical theory. :-)

Saturation issues have nothing to do with drawing power via a
transformer's secondary. The problem arises out of the magnetization
current increasing (due to either insufficient turns or else,
equivalently, excess voltage) to the point that the magnetic flux in the
core reaches a level that saturates the magnetic core material used.

There is an art to manufacturing an old fashioned wallwart transformer
as cheaply as possible such as those often hot running chinese wallwarts
where they've calculated not only the thinnest of wire to be used but
also the minimum number of turns required for the nominal voltage rating
without inducing excessive saturation effects. As a consequence, such
transformer designs leave no margin whatsoever for over-volting events in
the mains supply.

The heating effect in such transformers under no-load conditions is
typically a watt or two both from I squared losses due to the saturation
peaks causing transient reductions in the primary inductance which
results in corresponding current spikes and the increased hysteresis
losses in the core material itself.

In my search to find some figures on the magnitude of 'magnetisation
current' compared to the full load current, I noticed some interesting
animated graphs of core saturation effects in this wikipedia article

<https://en.wikipedia.org/wiki/Transformer#Real_transformer>.

Unfortunately, I wasn't able to find figures for transformer
magnetisation current which ISTR as being typically an order of magnitude
or so less than that due to their maximum load current ratings.

Using a pair of transformers wired as I suggested is an effective way to
eliminate any question regarding transformer saturation effects for the
sort of over-volting events being monitored. It's an arrangement that
allows for a 100% over-volting event to be measured without saturation
effects spoiling the integrity of the measurement of an event that would
instantly fry incandescent lamps and heater elements alike.

It doesn't matter that the transformers are only operating at half their
designed voltage rating. The arbitrarily low secondary voltage is simply
a faithful, low voltage, galvanically isolated replica of the mains
voltage being monitored anyway, the level of which will be calibrated so
that 240v corresponds to -10 or -20 dB of FSD in the audio recording
itself. Using an audio recording application to log the mains waveform is
just a quick 'n' dirty way to see whether or not there is anything of
interest to be logged in the first place.

--
Johnny B Good

[The Natural Philosopher]

I give up. What is the use of a degree in it and a year spent designing
transformers?


--
Canada is all right really, though not for the whole weekend.

"Saki"

[tony sayer]

In article <15sAC.925276$oi5.9...@fx43.am4>, dennis@home

<den...@invalid.invalid> scribeth thus

Isolating transformers are generally known to isolate a direct mains
connection.....
--
Tony Sayer

[tony sayer]

In article <56e8c72a...@candehope.me.uk>, charles
<cha...@candehope.me.uk> scribeth thus

Indeed they were, still got one 240 in and 240 out at around 5 kW..
--
Tony Sayer

[whisky-dave]

On Friday, 13 April 2018 20:45:16 UTC+1, Cursitor Doom wrote:

> On Fri, 13 Apr 2018 07:38:11 -0700, whisky-dave wrote:
>
> > Problem is dealing with mains AC voltages and having to reduce them
> > first.
>

> Not really. Loads of suitable sub-min mains transformers in every local
> recycling site; help yourself for free. Or just a couple of quid new from
> China through Ebay.

All you do then is reducing the overvolage to a level you might not detect with an ardunio.

[The Natural Philosopher]

????

Hsa the government been putting somnething in the water supply?


--
"In our post-modern world, climate science is not powerful because it is
true: it is true because it is powerful."

Lucas Bergkamp

[whisky-dave]

On Friday, 13 April 2018 22:22:14 UTC+1, dennis@home wrote:
> On 13/04/2018 15:38, whisky-dave wrote:
> > On Friday, 13 April 2018 15:23:29 UTC+1, dennis@home wrote:
> >> On 13/04/2018 10:24, newshound wrote:
> >>> On 13/04/2018 07:48, Halmyre wrote:
> >>>> On Thursday, April 12, 2018 at 1:59:45 PM UTC+1, newshound
> >>>> wrote:
> >>>>> On 12/04/2018 12:51, The Nomad wrote:
> >>>>>> On Thu, 12 Apr 2018 12:37:06 +0100, newshound
> >>>>>> <news...@stevejqr.plus.com> wrote:
> >>>>>>
> >>>>>>> For reasons I won't bore you with, I'm interested in
> >>>>>>> building a cheap, simple data logger to monitor mains
> >>>>>>> voltage, ideally two channels (live to earth and neutral
> >>>>>>> to earth). In the dim and distant past I have designed
> >>>>>>> and built such things more or less from scratch, but
> >>>>>>> surely someone has already done this.
> >>>>>>>
> >>>>>>> I havn't used either Arduino or Pi before, but I assume
> >>>>>>> one or other would be the obvious starting point.
> >>>>>>>
> >>>>>>> However ATM google isn't giving me a strong lead.
> >>>>>>> Thoughts?
> >>>>>>
> >>>>>> A quick google came up with:
> >>>>>>
> >>>>>> <https://openenergymonitor.org/forum-archive/node/58.html>
> >>>>>>
> >>>>>> <https://circuitdigest.com/microcontroller-projects/arduino-ac-voltmeter>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> <https://www.briandorey.com/post/arduino-mains-voltage-and-current-
> >>>>>> logging>
> >>>>>>
> >>>>>> Avpx
> >>>>>>
> >>>>> Thanks, that second one looks like a good basis.
> >>>>
> >>>> Won't the capacitor smooth out any transients you might want to
> >>>> observe?
> >>>>
> >>> I am looking for transients longer than maybe a second or so.
> >>> Obviously, might need to experiment with capacitors a bit.
> >>
> >> You need a simple mains transformer to a few volts and feed it
> >> into the A-D converter on an arduino and do some maths on the
> >> samples.
> >
> > How often will it sample and what sort levels of spikes and
> > transcients. And don't forget the ADC can only really 'see' DC
> > voltages.
>
> AC is just DC with an offset.

Yeah sure it is.

Idiot.

In direct current (DC), the electric charge (current) only flows in one direction. Electric charge in alternating current (AC), on the other hand, changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction.


Offset has nothing to do with it.


> >> Only a couple of resistors required to set the voltage range to be
> >> within the ADC input range.
> >
> > doesn't help much though, in fact depending on these spikes you might
> > not 'see' much after reducing it through a transformer and
> > rectifier.
>
> So we have something else you don't know much about.

but still a lot more than you do.
DC is NOT AC with an offset.

> >> A nodeMCU will almost certainly do everything you want including
> >> logging to a remote database.
> >

> > Problem is dealing with mains AC voltages and having to reduce them
> > first.
> >
>

> Isolating transformers isolate the mains and reduce them to safe levels.

Isoltaing transformers isolate that is why they are called Isolating
transformers. It is NOT always about reducing to a safe level, because there are pulse isolating transformer nothing to do woith isolating for safety reasons.

http://uk.farnell.com/wurth-elektronik/760301301/gate-driv-transfrmr-1-1-1-750uh/dp/2431618?mckv=z8r992i2_dc|pcrid|78108291069|&gross_price=true&CATCI=pla-131232739029&CAAGID=14983516629&CMP=KNC-GUK-GEN-SHOPPING-WURTH_ELEKTRONIK&CAGPSPN=pla&gclid=EAIaIQobChMIyIXt7cu-2gIVY7HtCh3HSw7qEAQYASABEgJiZvD_BwE&CAWELAID=120173390000290019

No who knows nothing.
isolating transformers aren't just about safer voltages.

[charles]

In article <6bTN4rCi...@bancom.co.uk>, tony sayer <to...@bancom.co.uk>
wrote:

Mine's not a big as that, but still quite heavy.

[whisky-dave]

On Saturday, 14 April 2018 20:39:07 UTC+1, newshound wrote:
> On 13/04/2018 21:14, tony sayer wrote:
>
> >
> >
> > So let me get this right your trying to find out why a steam wallpaper
> > stripper is failing?.
> >
> > I'd ask what make is it ?. Where is it made?
> >
> Modern Earlex, China I expect. 40 year old Earlex, UK I expect.
>
> > What's the actual specified mains voltage of the element in use for it?
>
> 220-240 volt
> >
> > What the local mains voltage as measured over few days sampling
>
> Today, it was 250. Sampling over a few days: THAT'S WHY I WANT A DATA LOGGER

A data logger won;t fix the problem, niether will buying an ardunio whether it's fakeardunio from ebay or the latest verion with wifi/bluetooth it'll be a waste of money, if you know you have 250V when you should really only have 230V then that is what needs sorting, an ardunio can't sort this problem out.

> and are
> > you in a rural overhead line fed area or urban underground?
>
> As I said earlier, it's rural on overhead lines

Perhaps you need a flying ardunio then ;-)

> > And has the same thing happened to any like for like replacements?...
>
> Half a dozen

time to stop measuring the problem and start sorting it.

[whisky-dave]

On Monday, 16 April 2018 11:30:35 UTC+1, The Natural Philosopher wrote:
> On 16/04/18 11:24, whisky-dave wrote:
> > On Friday, 13 April 2018 20:45:16 UTC+1, Cursitor Doom wrote:
> >> On Fri, 13 Apr 2018 07:38:11 -0700, whisky-dave wrote:
> >>
> >>> Problem is dealing with mains AC voltages and having to reduce them
> >>> first.
> >>
> >> Not really. Loads of suitable sub-min mains transformers in every local
> >> recycling site; help yourself for free. Or just a couple of quid new from
> >> China through Ebay.
> >
> > All you do then is reducing the overvolage to a level you might not detect with an ardunio.
> >
> >
> ????
>
> Hsa the government been putting somnething in the water supply?

Not sure who puts stuff in the water.

[Johnny B Good]

Heavy! I should say so! Based on my collection of 360VA transformers
which each weigh 16 Lbs or so. I'd estimate a 'Ballpark' figure for that
5KVA transformer to be somewhere around a couple of CWT! :-)

--
Johnny B Good

[NY]

"whisky-dave" <whisk...@gmail.com> wrote in message
news:342604bd-9307-4811...@googlegroups.com...

>> Today, it was 250. Sampling over a few days: THAT'S WHY I WANT A DATA
>> LOGGER
>
> A data logger won;t fix the problem, niether will buying an ardunio
> whether it's fakeardunio from ebay or the latest verion with
> wifi/bluetooth it'll be a waste of money, if you know you have 250V when
> you should really only have 230V then that is what needs sorting, an
> ardunio can't sort this problem out.

It doesn't *solve* the problem, but it supplies evidence of the fact that
there is a problem and the times when it occurs, which will (hopefully)
persuade the electricity supply company to investigate and rectify.

What intrigues me is that a fairly small over-voltage of 10V (*) is shorting
the life of the wallpaper stripper element so much. You'd expect other
heating elements (kettle, immersion heater, electric fire, cooker) would
suffer the same fate.


(*) www.twothirtyvolts.org.uk/pdfs/site-info/Explanation_230Volts.pdf says
230V + 6% -10% (so 216V to 253V) with a nominal voltage of 240V

[whisky-dave]

On Monday, 16 April 2018 12:28:21 UTC+1, NY wrote:
> "whisky-dave" <whisk...@gmail.com> wrote in message
> news:342604bd-9307-4811...@googlegroups.com...
> >> Today, it was 250. Sampling over a few days: THAT'S WHY I WANT A DATA
> >> LOGGER
> >
> > A data logger won;t fix the problem, niether will buying an ardunio
> > whether it's fakeardunio from ebay or the latest verion with
> > wifi/bluetooth it'll be a waste of money, if you know you have 250V when
> > you should really only have 230V then that is what needs sorting, an
> > ardunio can't sort this problem out.
>
> It doesn't *solve* the problem, but it supplies evidence of the fact that
> there is a problem and the times when it occurs, which will (hopefully)
> persuade the electricity supply company to investigate and rectify.

Seems a lot of effort if you already know that the mains gets to 250V can't you just photography the display on the DMM, if that isn't enough proof for the elec company, will a homemade measuring system be enough ?.

>
> What intrigues me is that a fairly small over-voltage of 10V (*) is shorting
> the life of the wallpaper stripper element so much. You'd expect other
> heating elements (kettle, immersion heater, electric fire, cooker) would
> suffer the same fate.

I would think the same, my wallpaper stripper has been in the loft for the past 8 years, so while I used mine for a few days that was it.

I assume the unit doesn't boil dry easily or moving it about has been eliminated as the cause, maybe there's a dodgy connection somewhere.

It does seem starnge that a voltage of just 250V would have this effect even if it was for 10 mins or so I'd expect a cutout to go.

I'd expect the electric company would be able to provide a mains monitor for their own satisfaction rathe rthan believe some home made device.

[Andy Burns]

whisky-dave wrote:

> if you know you have 250V when you should really only have 230V
> then that is what needs sorting

Good luck getting 250V looked at, the ESQCR says 216-253V is permitted.

[NY]

"Andy Burns" <use...@andyburns.uk> wrote in message
news:fjji5f...@mid.individual.net...

In other words, equipment should be able to perform adequately over this
range without malfunctioning.

[whisky-dave]

So while spending money on an arduino and all the hassle of setting it up just to prove that the voltage goes to 250V and blows a wallpaper stripper element will do what exactly, might be fun to do if you have the time on your hands and like doing this sort of thing fine.
But I would have brought a differnt wallpaper sripper long before that if the one I had kept going faulty after just one or two elements.

[Andy Burns]

whisky-dave wrote:

> all the hassle of setting it up just to prove that the voltage goes to 250V
> and blows a wallpaper stripper element will do what exactly

photonicinduction seems to get kettles up to 320-440V before they pop...

[whisky-dave]

We can all overload stuff :)

https://www.flickr.com/photos/whiskydave/21985492221/

[dennis@home]

On 16/04/2018 11:48, whisky-dave wrote:

> A data logger won;t fix the problem, niether will buying an ardunio
> whether it's fakeardunio from ebay or the latest verion with
> wifi/bluetooth it'll be a waste of money, if you know you have 250V
> when you should really only have 230V then that is what needs
> sorting, an ardunio can't sort this problem out.
>
>

250V is within the tolerance for UK mains voltage!

[charles]

In article <XK3BC.503053$TP2.1...@fx01.am4>,

Indeed so: 216.2 - 253.0 V is the range.

[newshound]

+1

[newshound]

Three different types of element so far. I've been looking for an excuse
to play with one of these for some time, and this provides it. I have
other uses for it once I have climbed the learning curve. Like other
posters, I am deeply skeptical that it is over-voltage. But that is one
possibility that is comparatively easy to test.

[whisky-dave]

Then maybe those kettle elements weren;t meant to run on UK electricity or just wasn't spec'd right a bit like certain types of cladding.
I don't remember seeing a link to these elements that kept needing to be replaced.

Of course one problem of running a kettle element in a wall paper stripper is that kettle elements are designed to be switched off immedaitly after they have reach their temerature whereas a wallpaper stripper is meant to keep boiling or be kept very close to boiling point for mins if not an hour or more.

[whisky-dave]

On Tuesday, 17 April 2018 09:44:42 UTC+1, newshound wrote:
> On 16/04/2018 15:39, whisky-dave wrote:
> > On Monday, 16 April 2018 14:32:04 UTC+1, NY wrote:
> >> "Andy Burns" <use...@andyburns.uk> wrote in message
> >> news:fjji5f...@mid.individual.net...
> >>> whisky-dave wrote:
> >>>
> >>>> if you know you have 250V when you should really only have 230V then that
> >>>> is what needs sorting
> >>>
> >>> Good luck getting 250V looked at, the ESQCR says 216-253V is permitted.
> >>
> >> In other words, equipment should be able to perform adequately over this
> >> range without malfunctioning.
> >
> > So while spending money on an arduino and all the hassle of setting it up just to prove that the voltage goes to 250V and blows a wallpaper stripper element will do what exactly, might be fun to do if you have the time on your hands and like doing this sort of thing fine.
> > But I would have brought a differnt wallpaper sripper long before that if the one I had kept going faulty after just one or two elements.
> >
> Three different types of element so far.

What are these differnt types ?

> I've been looking for an excuse
> to play with one of these for some time, and this provides it.

true this sort of thing can be fun, people thought I was strange because I brought a webcam so I could see cats in my garden and observe my cat flap 24/7.

> I have
> other uses for it once I have climbed the learning curve.

That's good Arduinios can be fun to experiment with and quite amazing for the price and size. 14 in/outs 6 analogue inputs.

> Like other
> posters, I am deeply skeptical that it is over-voltage. But that is one
> possibility that is comparatively easy to test.

True but testing it accuratly over time might not be that easy with an ardunino but it depends on what's actually being tested and the timescale.

I could be used to monitor various points in the house to see where such voltage spikes might be occuring is it everywhere or just one place.
Maybe the earth isn;t 'correct' and floating or something.

A webcam looking at a DVM display would also work and less hassle.
I'm recycling arduinos from last years projects have abou 6 so far that I think might still work, another dozen or so to go.

Would be an interesting project for students but there's no way I'd let them record anything much over 30V.

[Martin Brown]

On 13/04/2018 17:21, newshound wrote:
> On 13/04/2018 16:44, whisky-dave wrote:
>> On Friday, 13 April 2018 15:44:58 UTC+1, The Natural Philosopher  wrote:
>>
>>>> Thanks, yes I agree completely about the sampling strategy, but I'd
>>>> sort
>>>> out details once I knew the capability of the device. My point was that
>>>> I think I am looking for slowish variations rather than microsecond
>>>> transients. (I am trying to find what is killing electric kettle
>>>> elements).
>>>
>>> My point is, do the low pass filtering in software, though.
>>>
>>> A bridge rectifier and smoothing cap is a peak voltage reading abortion
>>> for this: you want to do an RMS average especially for kettle elements.
>>>
>>> My solution is less components, but more code.
>>>
>>> Code is cheap!
>>
>> Depending on how long it takes you.
>> The idea device would just be a pen holder that respondened to changes
>> in the voltage a bit like an old chart recorder and I'm still not sure
>> how you'll detect what's blowing a kettle elimante I wouldn't have
>> thought they'd be suseptable to transients.
>>>
>>> Only issue is doing a square root in binary integers...arduinos don't
>>> have native floating point shit!

Shifts to get the nearest power of two and then.

Sqrt(1+x) = 1 + 2x/(4+x)

suitably scaled.

>> I'm still note sure how you'll know what caused teh transcient even
>> after detecting it.
>>
>> How long will this kettle element be ON for ?

> OK, it's not an element in a kettle. It's in a wallpaper stripper, used
> as a steam generator. They are typically failing after half a dozen
> (separate) 20 minute sessions. They are not being boiled dry, they are
> on a timer to prevent that. Oh, and nothing else seems to be blowing. I
> *originally* thought it must be a problem with the chemistry of the
> local water supply but two separate chemists with long experience are
> convinced that this is unlikely.

It seems to me even less likely that a kettle element device will even
notice a mains transient. A thin filament bulb might blow and ours used
to sometimes when the local pumping station was able to create big
transient glitches on the mains. It was fixed by a new (bigger) cable.

Sounds more like you are boiling it dry or using water so hard that in
20 minutes the layer of clay is enough to cause a thermal cutout.

If the mains was 5% high then you get 10% more power dissipated in the
heater element since it is run at almost constant temperature of boiling
water. Worst that should happen is 10% more steam out unless the steam
cannot escape fast enough. Mains going 50% high might easily break it
but would have disastrous effects on many domestic appliances too.

If you are not blowing filament light bulbs as well then the fault more
probably lies with the device that is failing repeatedly.

--
Regards,
Martin Brown

[T i m]

On Sun, 15 Apr 2018 12:19:16 +0100, newshound
<news...@stevejqr.plus.com> wrote:

<snip>

>Seeing 250 volts on my single measurement makes me more inclined to
>think it is worth doing some logging.

Whilst not the fun of playing with an Arduino for such things, I
wonder what sort of peak voltage one of the plug-in mains power
monitors might be able to store (thinking I had seen such a function
on one of mine?).

Knowing how bad my 'roundtuit' timer can be I was considering using
one of the USB dataloggers to monitor some 12V battery applications.

http://www.omniinstruments.co.uk/el-usb-3-voltage-data-logger.html

If you had your mini-mains transformer, a bridge rec and suitable cap
(to match the characteristics of the monitor to give the fastest
response) I wonder if that might give you something that would be
quicker to setup and equally useful for other (battery monitoring)
type experiments?

Cheers, T i m

[Cursitor Doom]

On Sat, 14 Apr 2018 13:29:54 +0100, tony sayer wrote:

> Care to expand of that statement Dennis?..

This thread must take the biscuit for the most absolute BOLLOCKS ever
written on Usenet (and that's saying something). I hope no one in the
future looks through some of the replies from certain people here and
ends up getting themselves killed from the 'advice' given.




--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
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protocols constitutes acceptance of this condition.

[Cursitor Doom]

On Mon, 16 Apr 2018 09:16:34 +0100, tony sayer wrote:

> Indeed they were, still got one 240 in and 240 out at around 5 kW..

5 kVA to be scrupulous about it. I had 3 x 500VA isolating trannies but
gave one away to a friend who was having to work with live switchers
direct from the mains. I'm kind like that. ;-)

[Cursitor Doom]

On Mon, 16 Apr 2018 03:35:01 -0700, whisky-dave wrote:

> No who knows nothing.
> isolating transformers aren't just about safer voltages.

Not about "safer voltages" (whatever that means) at all. A pure mains
isolating transformer takes 230V in and gives ~230V out. The key
differences are that the insertion of the IT into the supply limits the
amount of energy you can draw vs. the bare mains. The IT also breaks the
ground reference that bare mains has to Earth (this important safety
aspect seems to go over most folks' heads!)

[newshound]

Maybe if it was under a tenner. I don't see that being particularly
versatile, and at that price you are approaching Arduino territory
(given that I have a fairly good collection of "useful bits). But I
appreciate the suggestion.

[newshound]

On 17/04/2018 22:57, Cursitor Doom wrote:
> On Sat, 14 Apr 2018 13:29:54 +0100, tony sayer wrote:
>
>> Care to expand of that statement Dennis?..
>
> This thread must take the biscuit for the most absolute BOLLOCKS ever
> written on Usenet (and that's saying something). I hope no one in the
> future looks through some of the replies from certain people here and
> ends up getting themselves killed from the 'advice' given.
>
>
>
>

Fame at last!