From time to time, we seem to experience a power "glitch", once a
day, at roughly the same time -- usually ~3AM. (but, not every day...
just "periods" when it manifests followed by periods where it is
completely absent).

It's not a problem, for the most part, as everything is on UPSs, here
(the microwave oven seems to complain the most as it isn't on a UPS
and its damn clock often resets -- I long for the day when appliances
have synchronized clocks or NO clocks!!!)

I assume this is some sort of switching transient that affects the
entire city (?) -- or, at least large portions of it.

(our services are below grade so not likely caused by something
physically interfering with the transmission lines)

I'm turning my attention to the design of the power systems for
my current project and figure it would be prudent to put some
line-monitoring capabilities into it (if only to let it anticipate
such problems and plan ahead).

So, the questions are:
- how often to sample (to be able to catch transient events)
- maximum peak likely to be encountered

[Of course, I have to anticipate what the power conditions are
likely to be in other parts of the market (US consumer and,
separately, commercial/industrial) and not just rely on my own
observations.]

I'm tempted to buy a line monitor just to see what they've done
(in terms of hardware interface; the signal processing software
won't be a problem). Recommendations? (again, two/three different
markets, as above)

On 30/3/22 1:25 pm, Don Y wrote:
> From time to time, we seem to experience a power "glitch", once a
> day, at roughly the same time -- usually ~3AM.  (but, not every day...
> just "periods" when it manifests followed by periods where it is
> completely absent).
>
> It's not a problem, for the most part, as everything is on UPSs, here
> (the microwave oven seems to complain the most as it isn't on a UPS
> and its damn clock often resets -- I long for the day when appliances
> have synchronized clocks or NO clocks!!!)
>
> I assume this is some sort of switching transient that affects the
> entire city (?) -- or, at least large portions of it.

We had repeated trips of the whole-house RCD every few days for months.
Always at 7:58AM. ALWAYS. I turned off everything in the house that
could know the time of day, and they still happened. Eventually I became
certain that it was something to do with the power supply, and started
harassing our provider.

They kept fobbing me off, saying I should replace the RCD - which at the
time was brand-new, after a renovation where we got a new powerboard,
and I told them that and insisted.

Eventually they admitted that 7:58AM is when they switch in some large
PFC capacitors in preparation for inductive industrial loads coming
alive. I told them that it was therefore their problem, and they
arranged to send a couple of electricians around to fit a more tolerant
RCD, at no cost to me.

When the sparkies came, they said they had been doing *hundreds* like
this. And that's just for the households who figured it out, and
complained long and hard enough to wear down the power company.

This was in 2000, before we started fitting RCD breakers on every circuit.

Clifford Heath.

On 30/03/2022 03:25, Don Y wrote:
> From time to time, we seem to experience a power "glitch", once a
> day, at roughly the same time -- usually ~3AM. (but, not every day...
> just "periods" when it manifests followed by periods where it is
> completely absent).
>
> It's not a problem, for the most part, as everything is on UPSs, here
> (the microwave oven seems to complain the most as it isn't on a UPS
> and its damn clock often resets -- I long for the day when appliances
> have synchronized clocks or NO clocks!!!)
>
> I assume this is some sort of switching transient that affects the
> entire city (?) -- or, at least large portions of it.
>
> (our services are below grade so not likely caused by something
> physically interfering with the transmission lines)
>
> I'm turning my attention to the design of the power systems for
> my current project and figure it would be prudent to put some
> line-monitoring capabilities into it (if only to let it anticipate
> such problems and plan ahead).
>
> So, the questions are:
> - how often to sample (to be able to catch transient events)
> - maximum peak likely to be encountered
>
> [Of course, I have to anticipate what the power conditions are
> likely to be in other parts of the market (US consumer and,
> separately, commercial/industrial) and not just rely on my own
> observations.]
>
> I'm tempted to buy a line monitor just to see what they've done
> (in terms of hardware interface; the signal processing software
> won't be a problem). Recommendations? (again, two/three different
> markets, as above)

Just get a 'scope monitoring the line power supply. Point a video camera
(preferably with continuous time display) at the screen and record a few
minutes before and after 3am every day. You should be able to record the
spike and the exact time it appears. Even a webcam on a laptop might do
the job. The power supply company wouldn't be able to argue with that
sort of evidence.

3am seems a strange time for transients. Some sort of fairly regular
maintenance work at the generation station or distribution switching,
perhaps?

--

Jeff

On a sunny day (Tue, 29 Mar 2022 19:25:13 -0700) it happened Don Y
<blockedofcourse@foo.invalid> wrote in <t20f2p$ob9$1@dont-email.me>:

> From time to time, we seem to experience a power "glitch", once a
>day, at roughly the same time -- usually ~3AM. (but, not every day...
>just "periods" when it manifests followed by periods where it is
>completely absent).
>
>It's not a problem, for the most part, as everything is on UPSs, here
>(the microwave oven seems to complain the most as it isn't on a UPS
>and its damn clock often resets -- I long for the day when appliances
>have synchronized clocks or NO clocks!!!)
>
>I assume this is some sort of switching transient that affects the
>entire city (?) -- or, at least large portions of it.
>
>(our services are below grade so not likely caused by something
>physically interfering with the transmission lines)
>
>I'm turning my attention to the design of the power systems for
>my current project and figure it would be prudent to put some
>line-monitoring capabilities into it (if only to let it anticipate
>such problems and plan ahead).
>
>So, the questions are:
>- how often to sample (to be able to catch transient events)
>- maximum peak likely to be encountered
>
>[Of course, I have to anticipate what the power conditions are
>likely to be in other parts of the market (US consumer and,
>separately, commercial/industrial) and not just rely on my own
>observations.]
>
>I'm tempted to buy a line monitor just to see what they've done
>(in terms of hardware interface; the signal processing software
>won't be a problem). Recommendations? (again, two/three different
>markets, as above)

The power network over here switches, sometimes 2 times a day, between networks it seems.
This causes a short (usually less than a second) power dip.
UPS takes care of that as far as computers go.
Laptop has its on battery and will run much longer,
For longer power failures (will keep watching satellite, radio, ham radio, etc)
I have now a 250 AH 12 V lifepo4 battery and a 2 kW 12V to 230V pure sinewave converter.
So if the UPS starts screaming when power goes for a longer time,
then it takes a few minutes to switch the big stuff to that setup manually.
Sure, the clock in the microwave will reset,,,,
Happened a few weeks back, 2 hours no power, neighbor came to ask 'Have you no power too?'
Well, yes and no, I was just switching to the big battery.
Talk about clocks, last Sunday we went to summer time, had to adjust 13 clocks here
Sure hope they get rid of that shit twice a year

The lifepo4 can easily power a microwave or cooking plate, or the TV for a whole evening..

On 2022-03-30 09:18, Jeff Layman wrote:

> Just get a 'scope monitoring the line power supply. Point a video camera
> (preferably with continuous time display) at the screen and record a few
> minutes before and after 3am every day. You should be able to record the
> spike and the exact time it appears. Even a webcam on a laptop might do
> the job. The power supply company wouldn't be able to argue with that
> sort of evidence.
>
> 3am seems a strange time for transients. Some sort of fairly regular
> maintenance work at the generation station or distribution switching,
> perhaps?
>

Or better: use a low voltage transformer and a resistive attenuator,
then capture the 1Vpp waveform on the LINE IN audio channel of a laptop.
Capture and analyze using e.g. the free Audacity, it shows the waveform
nicely. Much easier than trying to find a transient on a video (even
when the scope did capture it - some scopes have a low acquisition frame
rate and may miss a spike completely).

Arie

On 3/30/2022 12:18 AM, Jeff Layman wrote:
> On 30/03/2022 03:25, Don Y wrote:
>> From time to time, we seem to experience a power "glitch", once a
>> day, at roughly the same time -- usually ~3AM. (but, not every day...
>> just "periods" when it manifests followed by periods where it is
>> completely absent).
>>
>> It's not a problem, for the most part, as everything is on UPSs, here
>> (the microwave oven seems to complain the most as it isn't on a UPS
>> and its damn clock often resets -- I long for the day when appliances
>> have synchronized clocks or NO clocks!!!)
>>
>> I assume this is some sort of switching transient that affects the
>> entire city (?) -- or, at least large portions of it.
>>
>> (our services are below grade so not likely caused by something
>> physically interfering with the transmission lines)
>>
>> I'm turning my attention to the design of the power systems for
>> my current project and figure it would be prudent to put some
>> line-monitoring capabilities into it (if only to let it anticipate
>> such problems and plan ahead).
>>
>> So, the questions are:
>> - how often to sample (to be able to catch transient events)
>> - maximum peak likely to be encountered
>>
>> [Of course, I have to anticipate what the power conditions are
>> likely to be in other parts of the market (US consumer and,
>> separately, commercial/industrial) and not just rely on my own
>> observations.]
>>
>> I'm tempted to buy a line monitor just to see what they've done
>> (in terms of hardware interface; the signal processing software
>> won't be a problem). Recommendations? (again, two/three different
>> markets, as above)
>
> Just get a 'scope monitoring the line power supply. Point a video camera
> (preferably with continuous time display) at the screen and record a few
> minutes before and after 3am every day. You should be able to record the spike
> and the exact time it appears. Even a webcam on a laptop might do the job. The
> power supply company wouldn't be able to argue with that sort of evidence.

I'm not particularly concerned with *my* experience:

It's not a problem, for the most part, as everything is on UPSs, here
(the microwave oven seems to complain the most as it isn't on a UPS
and its damn clock often resets -- I long for the day when appliances
have synchronized clocks or NO clocks!!!)

Rather, I'm concerned with adding that monitoring capability to my
product so *it* can learn/know what the "local" power conditions happen
to be (it runs 24/7/365). This would help it decide how to adjust the
load and schedule processes in anticipation of (or after detection of)
outages.

For example, *real* outages, here, have been very infrequent. And, have
have always been the result of equipment outages: cable segment failures,
blown fuses in the neighborhood distribution station, etc. As these are
relatively small events, from the perspective of the utility company, (unlike
a storm knocking out power to a large portion of a town) they can be
addressed with a small crew dispatched in short order. In each case, our
outage has typically been less than ~6 hours (before they've rerouted power
from "the other end" of the feed).

By contrast, when I lived in the midwest, we had outages pretty regularly
(6 or more each year) and they persisted for longer periods.

So, siting my device *here* it could opt to maintain power for a larger
portion of its componentry (it can selectively shed load) for a longer
period of time and still hope to have spare backup capacity. In the
midwest, it would have had to learn to impose deeper cuts as it expected
longer outages.

It also lets the size of the (battery) backup be an independent parameter
at the discretion of the owner instead of an implicit requirement of the
design. A deployment with a bigger load looks like a nominal deployment
with a smaller backup, etc.

[e.g., I have a ~2200W load that I can keep fully operational for ~2hrs.
Someone else might not want to make that investment -- or might have
a BIGGER load -- so the system needs to know how to make tradeoffs in
scheduling its load]

Finally, being able to guesstimate the likelihood of an outage, based on
past observations. For example, if power fails, returns and then fails,
again, you'd be slow to reinstall load hoping instead, to let the power
supply divert power to RE-charging instead of the load (which you expect
to likely need to *shed*, again, RSN... when the followup outage strikes)

[This has been the pattern, here, with power coming back on-line. The
crews will initially diagnose the problem, restore power -- and have
the problem manifest, again, in short order ("Hey, Bill, the short is
still there...")]

I'm hoping that by being able to *look* at the mains as they are powering
the system, that it might be able to make some deductions about the
possible cause (and duration) of the outage. Instead of being "surprised"
by each new event!

> 3am seems a strange time for transients. Some sort of fairly regular
> maintenance work at the generation station or distribution switching, perhaps?

Dunno. As I can't tell how widespread the problem is (it just this
neighborhood? this side of town? etc.) or the system elements that
lie between me and the "problem", I can't guess as to its cause.
Is it something related to some other "nearby" power consumer and
not the supplier? <shrug>

The UPSs all claim it to be "excessive rate of change" (or something to
that effect... not "dropped cycle" or "low line" or...).

In parts of town with overhead distribution (which likely includes the
high tension feeding us... somewhere), I can see large "switches"
(but no idea as to how -- or why -- they are actuated/opened)

Again, the cause is likely out of my control (unless a local fault).
I just want to be able to observe it in more detail than "gee, the
lights flickered" or "ooops! power is out!"

Hence the question as to what the appropriate capabilities of that
data acquisition (sub)system...

Arie de Muijnck <eternal.september@ademu.com> wrote:

> On 2022-03-30 09:18, Jeff Layman wrote:
>
>> Just get a 'scope monitoring the line power supply. Point a video camera
>> (preferably with continuous time display) at the screen and record a few
>> minutes before and after 3am every day. You should be able to record the
>> spike and the exact time it appears. Even a webcam on a laptop might do
>> the job. The power supply company wouldn't be able to argue with that
>> sort of evidence.
>>
>> 3am seems a strange time for transients. Some sort of fairly regular
>> maintenance work at the generation station or distribution switching,
>> perhaps?
>>
>
> Or better: use a low voltage transformer and a resistive attenuator,
> then capture the 1Vpp waveform on the LINE IN audio channel of a laptop.
> Capture and analyze using e.g. the free Audacity, it shows the waveform
> nicely. Much easier than trying to find a transient on a video (even
> when the scope did capture it - some scopes have a low acquisition frame
> rate and may miss a spike completely).
>
> Arie

A transformer will have poor high frequency response and will filter out
sharp spikes. Better to use a 100:1 capacitive/resistive divider across the
AC line voltage. Verify the LINE IN audio channel is 600 ohms, then add a
600k across the top capacitor.

The neutral doesn't have to connect to the chassis of the computer. If you
do, it will likely blow any GFI breaker that is on the ac line. Use GND for
the return.

--
MRM

On Wednesday, 30 March 2022 at 12:09:14 UTC+1, Mike Monett wrote:
> Arie de Muijnck <eternal....@ademu.com> wrote:
>
> > On 2022-03-30 09:18, Jeff Layman wrote:
> >
> >> Just get a 'scope monitoring the line power supply. Point a video camera
> >> (preferably with continuous time display) at the screen and record a few
> >> minutes before and after 3am every day. You should be able to record the
> >> spike and the exact time it appears. Even a webcam on a laptop might do
> >> the job. The power supply company wouldn't be able to argue with that
> >> sort of evidence.
> >>
> >> 3am seems a strange time for transients. Some sort of fairly regular
> >> maintenance work at the generation station or distribution switching,
> >> perhaps?
> >>
> >
> > Or better: use a low voltage transformer and a resistive attenuator,
> > then capture the 1Vpp waveform on the LINE IN audio channel of a laptop.
> > Capture and analyze using e.g. the free Audacity, it shows the waveform
> > nicely. Much easier than trying to find a transient on a video (even
> > when the scope did capture it - some scopes have a low acquisition frame
> > rate and may miss a spike completely).
> >
> > Arie
> A transformer will have poor high frequency response and will filter out
> sharp spikes. Better to use a 100:1 capacitive/resistive divider across the
> AC line voltage. Verify the LINE IN audio channel is 600 ohms, then add a
> 600k across the top capacitor.
>
> The neutral doesn't have to connect to the chassis of the computer. If you
> do, it will likely blow any GFI breaker that is on the ac line. Use GND for
> the return.

But are sharp spikes likely to be a problem? Any product which has been
through regulatory testing will have demonstrated a good immunity to
large short spikes, so it is much more likely that dropouts will cause
problems.
A small transformer will respond to frequencies of many kHz, so that should
be enough. What will prevent it from measuring large spikes is core
saturation but there are several ways of minimising the effects of this
that have been discussed here in the past.
Most products, especially those with switched mode power supplies,
should survive dropouts of 10ms or less without any problems
due to energy storage in their input capacitors.

John

On 3/30/2022 4:41 AM, John Walliker wrote:
> On Wednesday, 30 March 2022 at 12:09:14 UTC+1, Mike Monett wrote:
>> Arie de Muijnck <eternal....@ademu.com> wrote:
>>
>>> On 2022-03-30 09:18, Jeff Layman wrote:
>>>
>>>> Just get a 'scope monitoring the line power supply. Point a video camera
>>>> (preferably with continuous time display) at the screen and record a few
>>>> minutes before and after 3am every day. You should be able to record the
>>>> spike and the exact time it appears. Even a webcam on a laptop might do
>>>> the job. The power supply company wouldn't be able to argue with that
>>>> sort of evidence.
>>>>
>>>> 3am seems a strange time for transients. Some sort of fairly regular
>>>> maintenance work at the generation station or distribution switching,
>>>> perhaps?
>>>>
>>>
>>> Or better: use a low voltage transformer and a resistive attenuator,
>>> then capture the 1Vpp waveform on the LINE IN audio channel of a laptop.
>>> Capture and analyze using e.g. the free Audacity, it shows the waveform
>>> nicely. Much easier than trying to find a transient on a video (even
>>> when the scope did capture it - some scopes have a low acquisition frame
>>> rate and may miss a spike completely).
>>>
>>> Arie
>> A transformer will have poor high frequency response and will filter out
>> sharp spikes. Better to use a 100:1 capacitive/resistive divider across the
>> AC line voltage. Verify the LINE IN audio channel is 600 ohms, then add a
>> 600k across the top capacitor.
>>
>> The neutral doesn't have to connect to the chassis of the computer. If you
>> do, it will likely blow any GFI breaker that is on the ac line. Use GND for
>> the return.
>
> But are sharp spikes likely to be a problem? Any product which has been
> through regulatory testing will have demonstrated a good immunity to
> large short spikes, so it is much more likely that dropouts will cause
> problems.

You've missed the point of (my!) post. The goal isn't to "protect" the
device -- OBSERVING the line won't do anything to make the device more
resilient!

Rather, the goal is to try to understand the nature of the disturbance
in light of other, "previously recorded (quantified)" disturbances and
use that to predict what is likely to happen with the mains, "soon".

E.g., when our cable segments fail (each transformer is daisy-chained
to the next transformer down the line -- unlike "taps" on an overhead
distribution line), the center/current carrying conductor (it's a coax)
shorts to the "shield" (neutral/ground). As such, you would expect to
"see" this arcing event instead of a "clean" open.

You can imagine that power won't be coming back anytime soon in the
event of such an observation.

A drunk slamming into a pole (overhead supply) would likely exhibit
a different sort of "failure event".

A brownout, still different.

Etc. Unless you can claim that those "details" carry no information,
then one would want to preserve as much data as possible.

[I can detect an outage just by counting 60Hz cycles and "timing out"
in ~20ms; doesn't tell me anything other than "power is out!"]

I'm not limited to just observations of the mains but can also factor in
*other* observations (e.g., it is summer and ACbrrr loading, on the network,
is high; or, it is winter and an ice-coated branch may have taken out
an overhead line)

> A small transformer will respond to frequencies of many kHz, so that should
> be enough. What will prevent it from measuring large spikes is core
> saturation but there are several ways of minimising the effects of this
> that have been discussed here in the past.
> Most products, especially those with switched mode power supplies,
> should survive dropouts of 10ms or less without any problems
> due to energy storage in their input capacitors.
>
> John
>

On Wednesday, 30 March 2022 at 13:12:48 UTC+1, Don Y wrote:

> You've missed the point of (my!) post. The goal isn't to "protect" the
> device -- OBSERVING the line won't do anything to make the device more
> resilient!
>
OK. I can see why measuring disturbances that won't affect your
devices could be useful. The question then becomes one of how
much measurement bandwidth and resolution is necessary to get
this unknown information and how best to acquire it and process it.
As you don't know what you are looking for about the only
bandwidth constraint is going to be the bandwidth of the power
transmission system subject to avoiding frequencies high enough
to have long-wave broadcast transmissions. That suggests an
upper frequency limit of maybe tens of kHz. Of course, arcing in
nearby wiring could have much higher frequency components.
Maybe its worth looking at how arc fault interrupters detect arcing?
John

On 3/30/2022 12:11 AM, Clifford Heath wrote:
> We had repeated trips of the whole-house RCD every few days for months.
>...

RCD - residual-current device or ground fault circuit interrupter (GFCI)

On 3/30/2022 6:34 AM, John Walliker wrote:
> On Wednesday, 30 March 2022 at 13:12:48 UTC+1, Don Y wrote:
>
>> You've missed the point of (my!) post. The goal isn't to "protect" the
>> device -- OBSERVING the line won't do anything to make the device more
>> resilient!
>>
> OK. I can see why measuring disturbances that won't affect your
> devices could be useful. The question then becomes one of how
> much measurement bandwidth and resolution is necessary to get
> this unknown information and how best to acquire it and process it.

There are a fair number of publications (research) that describe faults
in the transmission network (because the utilities have an interest
in minimizing these). How those are reflected *into* a "point of
observation" that *I* would easily monitor is an issue. (telling
me what's happening on the high-tension side of my local feed isn't
the same thing as telling me what I will see "locally")

> As you don't know what you are looking for about the only
> bandwidth constraint is going to be the bandwidth of the power
> transmission system subject to avoiding frequencies high enough
> to have long-wave broadcast transmissions. That suggests an
> upper frequency limit of maybe tens of kHz.

But, that ignores:

> Of course, arcing in
> nearby wiring could have much higher frequency components.

....as well as other failures, noise sources, etc. E.g., a fault
in a large load that eventually takes out the local branch circuit
can be just as "bad" for your source of power as a system-wide
power failure.

Tens of Hz is enough to (quickly) detect *outages*. Will tens of
KHz be sufficient to differentiate between different line faults
and transients? How much wire do you assume separates the
observation from the fault?? <shrug>

[And, we've not addressed the magnitude of the transients... 10X?
log scale?]

> Maybe its worth looking at how arc fault interrupters detect arcing?

That's a good idea. But, again, they are only looking for arcing and
not the general case of "disturbances"/line quality. E.g., in an
industrial setting, I'd expect the mains to be a lot dirtier than
in a domestic setting. So, you'd have to "learn" when that "dirt"
is significant and when it just has to be tolerated.

And, they are obviously targeting "cheap" detection methods; I'm
not so constrained.

On Wed, 30 Mar 2022 07:22:43 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

>The power network over here switches, sometimes 2 times a day, between networks it seems.
>This causes a short (usually less than a second) power dip.
>UPS takes care of that as far as computers go.
>Laptop has its on battery and will run much longer,

I'd like to use a laptop for a control application in an unattended
location, instead of a big PC and a UPS. But a PC bios can usually be
set up to restart the PC after a hard power failure, and it seems like
laptops can't do that for some reason. I'd love to find one that does.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

On Tuesday, March 29, 2022 at 7:25:36 PM UTC-7, Don Y wrote:

> I'm turning my attention to the design of the power systems for
> my current project and figure it would be prudent to put some
> line-monitoring capabilities into it (if only to let it anticipate
> such problems and plan ahead).
>
> So, the questions are:
> - how often to sample (to be able to catch transient events)
> - maximum peak likely to be encountered

It's relatively important to have an average-AC-voltage measure,
because some wiring issues can be diagnosed that way; you'd want to
sample rectified/filtered V at tenth second or so, but only log 'events', not
keep all the data. There's a few percent variance allowable, of course.

Load changes and loose connections or lightning strikes, or
diurnal overvoltage because of xformer tap decisions could show up.
Sites vary, but expect 2kV for miliseconds, in case of lightning.

More important surges or loads will cause zero-cross timing shifts which
tie into odd clunks from motors, so I'd think to log also any deviation from
'normal' 120 (or 100) zero crossings per second. Maybe store a few dozen
cycles before and after an 'event', gives you an idea of the transient. Motor
starts without zero-voltage-switching have dimmed my lights and
several times rebooted a Linux box exactly when I hear the buzzsaw.

On Wednesday, March 30, 2022 at 12:27:44 PM UTC-7, John Larkin wrote:

> I'd like to use a laptop for a control application in an unattended
> location, instead of a big PC and a UPS. But a PC bios can usually be
> set up to restart the PC after a hard power failure, and it seems like
> laptops can't do that for some reason. I'd love to find one that does.

MacOS laptops can be scheduled for turn-on and/or off once a day, with
the 'energy saver' settings. UPS connection sometimes adds options, too.

On Wed, 30 Mar 2022 16:08:04 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Wednesday, March 30, 2022 at 12:27:44 PM UTC-7, John Larkin wrote:
>
>> I'd like to use a laptop for a control application in an unattended
>> location, instead of a big PC and a UPS. But a PC bios can usually be
>> set up to restart the PC after a hard power failure, and it seems like
>> laptops can't do that for some reason. I'd love to find one that does.
>
>MacOS laptops can be scheduled for turn-on and/or off once a day, with
>the 'energy saver' settings. UPS connection sometimes adds options, too.

I need a Windows machine. If power fails for a full day maybe, a
laptop will run out of battery power and shut down, but can't be set
up to restart when power comes back. At least none that I can find.

Strange.

Maybe some laptops can be set up to deep-sleep when batteries get low,
but wake up when power comes back. If one could ride out a few days
that way on remaining battery power, it would be OK.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

On 3/30/2022 2:58 PM, whit3rd wrote:

>> So, the questions are:
>> - how often to sample (to be able to catch transient events)
>> - maximum peak likely to be encountered
>
> It's relatively important to have an average-AC-voltage measure,
> because some wiring issues can be diagnosed that way; you'd want to
> sample rectified/filtered V at tenth second or so, but only log 'events', not
> keep all the data. There's a few percent variance allowable, of course.

But those would be "perform once" types of calculations; the wiring
isn't likely to change "dynamically".

> Load changes and loose connections or lightning strikes, or
> diurnal overvoltage because of xformer tap decisions could show up.
> Sites vary, but expect 2kV for miliseconds, in case of lightning.

OK. I assume we're still speaking of consumer deployments...

> More important surges or loads will cause zero-cross timing shifts which
> tie into odd clunks from motors, so I'd think to log also any deviation from
> 'normal' 120 (or 100) zero crossings per second. Maybe store a few dozen
> cycles before and after an 'event', gives you an idea of the transient. Motor
> starts without zero-voltage-switching have dimmed my lights and
> several times rebooted a Linux box exactly when I hear the buzzsaw.

Hmmm... I hadn't thought of keeping much "context".

The FNET folks sample at ~1.5KHz (I don't recall the precision) and try to
detect anomalies in the grid by coordinating observations from geographically
dispersed measurement stations. I assume some of their algorithms could be
applied to local "single observation" points.

As long as the "disturbance/transient" doesn't affect (or predict!) power
availability (as seen at the output of MY power supply), I'm likely not too
concerned with it. I can carry most of my (distributed) loads over short
durations, regardless of the investment a particular site may have made
in "backup" capability.

I'd have to be more concerned about sites that power individual nodes
"locally" from PSUs that aren't as robust. I will know that this is
happening (*has* happened) and can take some measures to prevent loss
of functionality. E.g., don't dispatch processes to nodes that may
not have reliable power at a particular site. Or, force the OS to
checkpoint every process running on those nodes (which adds overhead).

Ideally, I'd not want to take any prophylactic measures unless needed
as they translate into "overhead"/waste.

On 3/29/2022 10:11 PM, Clifford Heath wrote:
> On 30/3/22 1:25 pm, Don Y wrote:
>>  From time to time, we seem to experience a power "glitch", once a
>> day, at roughly the same time -- usually ~3AM.  (but, not every day...
>> just "periods" when it manifests followed by periods where it is
>> completely absent).
>>
>> It's not a problem, for the most part, as everything is on UPSs, here
>> (the microwave oven seems to complain the most as it isn't on a UPS
>> and its damn clock often resets -- I long for the day when appliances
>> have synchronized clocks or NO clocks!!!)
>>
>> I assume this is some sort of switching transient that affects the
>> entire city (?) -- or, at least large portions of it.
>
> We had repeated trips of the whole-house RCD every few days for months.
> Always at 7:58AM. ALWAYS. I turned off everything in the house that
> could know the time of day, and they still happened. Eventually I became
> certain that it was something to do with the power supply, and started
> harassing our provider.
>
> They kept fobbing me off, saying I should replace the RCD - which at the
> time was brand-new, after a renovation where we got a new powerboard,
> and I told them that and insisted.
>
> Eventually they admitted that 7:58AM is when they switch in some large
> PFC capacitors in preparation for inductive industrial loads coming
> alive. I told them that it was therefore their problem, and they
> arranged to send a couple of electricians around to fit a more tolerant
> RCD, at no cost to me.
>
> When the sparkies came, they said they had been doing *hundreds* like
> this. And that's just for the households who figured it out, and
> complained long and hard enough to wear down the power company.
>
> This was in 2000, before we started fitting RCD breakers on every circuit.
>
> Clifford Heath.

Switching of power factor caps is a known potential cause of significant
surges. Would be interesting why that trips a RCD.

On 3/30/2022 7:34 AM, John Walliker wrote:
>
> Maybe its worth looking at how arc fault interrupters detect arcing?
>

Note that AFCIs only detect arcing downstream. They ignore 'normal' arcs
like switch open/close.

On Wednesday, March 30, 2022 at 7:11:29 PM UTC-7, Don Y wrote:
> On 3/30/2022 2:58 PM, whit3rd wrote:
>
> >> So, the questions are:
> >> - how often to sample (to be able to catch transient events)
> >> - maximum peak likely to be encountered

> >... I'd think to log also any deviation from
> > 'normal' 120 (or 100) zero crossings per second. Maybe store a few dozen
> > cycles before and after an 'event', gives you an idea of the transient. Motor
> > starts without zero-voltage-switching have dimmed my lights and
> > several times rebooted a Linux box exactly when I hear the buzzsaw.
> Hmmm... I hadn't thought of keeping much "context".
>
> The FNET folks sample at ~1.5KHz (I don't recall the precision) and try to
> detect anomalies in the grid by coordinating observations from geographically
> dispersed measurement stations. I assume some of their algorithms could be
> applied to local "single observation" points.

Finding someone else's algorithms would be a good idea; I belatedly realize that a bit
of powerline signalling is done near zero crossings, and maybe timing peaks then
resetting the peak detector at zero crossings is a better way to go. A powerline
45 MHz Ethernet link wouldn't look benign.

On Wednesday, March 30, 2022 at 4:27:12 PM UTC-7, John Larkin wrote:
> On Wed, 30 Mar 2022 16:08:04 -0700 (PDT), whit3rd <whi...@gmail.com>
> wrote:
> >On Wednesday, March 30, 2022 at 12:27:44 PM UTC-7, John Larkin wrote:
> >
> >> I'd like to use a laptop for a control application in an unattended
> >> location, instead of a big PC and a UPS. But a PC bios can usually be
> >> set up to restart the PC after a hard power failure, and it seems like
> >> laptops can't do that for some reason. I'd love to find one that does.
> >
> >MacOS laptops can be scheduled for turn-on and/or off once a day, with
> >the 'energy saver' settings. UPS connection sometimes adds options, too.

> I need a Windows machine. If power fails for a full day maybe, a
> laptop will run out of battery power and shut down, but can't be set
> up to restart when power comes back. At least none that I can find.

So, load a Windows virtual machine into a MacBook. The energy manager
"schedule" settings will still work; set it to sleep soonish if only battery
is available.

It's not 'when power comes back' that you set, but an internal time-of-day start
time, and/or shutdown time. If power drops or not, it'll still start
the next day, at the appointed time, on battery. The battery/line-power status
would have to be checked by a script if you wanted any power-on event to make it reboot,
and no script can startup or wake-from-sleep on condition of power inlet status.

On a sunny day (Wed, 30 Mar 2022 12:27:32 -0700) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<4eb94hd6nturau50ev7muckgefj21h6nh0@4ax.com>:

>On Wed, 30 Mar 2022 07:22:43 GMT, Jan Panteltje
><pNaonStpealmtje@yahoo.com> wrote:
>
>
>>The power network over here switches, sometimes 2 times a day, between networks it seems.
>>This causes a short (usually less than a second) power dip.
>>UPS takes care of that as far as computers go.
>>Laptop has its on battery and will run much longer,
>
>I'd like to use a laptop for a control application in an unattended
>location, instead of a big PC and a UPS. But a PC bios can usually be
>set up to restart the PC after a hard power failure, and it seems like
>laptops can't do that for some reason. I'd love to find one that does.

Is that not mainly a BIOS config?
My laptop runs Linux, but I have specified a BIOS password, if you do not then it will boot normally AFAIK.
Same for my other older small laptop, was even running as web server for years.

Use a Raspberry?
I now have 5 of those in use.
Some just via SSH, no monitor no keyboard, like the one used as router,
Lower power use too.
There exist battery backup 'shields' for those.

On 3/30/2022 8:58 PM, whit3rd wrote:
> On Wednesday, March 30, 2022 at 7:11:29 PM UTC-7, Don Y wrote:
>> On 3/30/2022 2:58 PM, whit3rd wrote:
>>
>>>> So, the questions are:
>>>> - how often to sample (to be able to catch transient events)
>>>> - maximum peak likely to be encountered
>
>>> ... I'd think to log also any deviation from
>>> 'normal' 120 (or 100) zero crossings per second. Maybe store a few dozen
>>> cycles before and after an 'event', gives you an idea of the transient. Motor
>>> starts without zero-voltage-switching have dimmed my lights and
>>> several times rebooted a Linux box exactly when I hear the buzzsaw.
>> Hmmm... I hadn't thought of keeping much "context".
>>
>> The FNET folks sample at ~1.5KHz (I don't recall the precision) and try to
>> detect anomalies in the grid by coordinating observations from geographically
>> dispersed measurement stations. I assume some of their algorithms could be
>> applied to local "single observation" points.
>
> Finding someone else's algorithms would be a good idea;

There are three problems, there:
- they are looking for something different than what I seek
- they are academics (with notoriously crappy implementations)
- their algorithms may not be completely specified in the literature
(and CURRENT source code may not be publicly available from which to
extract those "latest details/discoveries")

> I belatedly realize that a bit
> of powerline signalling is done near zero crossings, and maybe timing peaks then
> resetting the peak detector at zero crossings is a better way to go. A powerline
> 45 MHz Ethernet link wouldn't look benign.

I was thinking do a DFT on the samples and extract the fundamental. From
that, go back and "pick" whatever points you want on the specific waveforms
for "actual observations".

On Thu, 31 Mar 2022 05:40:56 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

>On a sunny day (Wed, 30 Mar 2022 12:27:32 -0700) it happened John Larkin
><jlarkin@highland_atwork_technology.com> wrote in
><4eb94hd6nturau50ev7muckgefj21h6nh0@4ax.com>:
>
>>On Wed, 30 Mar 2022 07:22:43 GMT, Jan Panteltje
>><pNaonStpealmtje@yahoo.com> wrote:
>>
>>
>>>The power network over here switches, sometimes 2 times a day, between networks it seems.
>>>This causes a short (usually less than a second) power dip.
>>>UPS takes care of that as far as computers go.
>>>Laptop has its on battery and will run much longer,
>>
>>I'd like to use a laptop for a control application in an unattended
>>location, instead of a big PC and a UPS. But a PC bios can usually be
>>set up to restart the PC after a hard power failure, and it seems like
>>laptops can't do that for some reason. I'd love to find one that does.
>
>Is that not mainly a BIOS config?

Yes. Some big PCs have the powerup boot option in their BIOS, some
don't. I've not found a laptop that does.

--

I yam what I yam - Popeye

On a sunny day (Thu, 31 Mar 2022 07:10:37 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<afdb4h5f4bd3dej65ohb7ksrsug0skpifo@4ax.com>:

>On Thu, 31 Mar 2022 05:40:56 GMT, Jan Panteltje
><pNaonStpealmtje@yahoo.com> wrote:
>
>>On a sunny day (Wed, 30 Mar 2022 12:27:32 -0700) it happened John Larkin
>><jlarkin@highland_atwork_technology.com> wrote in
>><4eb94hd6nturau50ev7muckgefj21h6nh0@4ax.com>:
>>
>>>On Wed, 30 Mar 2022 07:22:43 GMT, Jan Panteltje
>>><pNaonStpealmtje@yahoo.com> wrote:
>>>
>>>
>>>>The power network over here switches, sometimes 2 times a day, between networks it seems.
>>>>This causes a short (usually less than a second) power dip.
>>>>UPS takes care of that as far as computers go.
>>>>Laptop has its on battery and will run much longer,
>>>
>>>I'd like to use a laptop for a control application in an unattended
>>>location, instead of a big PC and a UPS. But a PC bios can usually be
>>>set up to restart the PC after a hard power failure, and it seems like
>>>laptops can't do that for some reason. I'd love to find one that does.
>>
>>Is that not mainly a BIOS config?
>
>Yes. Some big PCs have the powerup boot option in their BIOS, some
>don't. I've not found a laptop that does.

OK, I think when the laptop powers off by itself it is because the battery is empty
it will need charging before it will boot again?
I wrote some software 'xbat' that runs on my laptop that makes it beep very loud when battery is low
http://panteltje.com/pub/xbat-0.5.tgz
Linux C code for X of course.

<quote from readme>
xbat uses ACPI and gets its info from /proc/acpi/battery/BAT1/state, try:
cat /proc/acpi/battery/BAT1/state

xbat displays battery level and time left on a charge in X.
The display is updated once per second.
If 3 minutes or less time is left, a 100 ms 4 kHz warning beep sounds every second.
The beep function requires siggen-2.3.10 to be installed,
it also requires access to the audio device.
<end quote>

You could make it power the laptop down early too (say with 1 hour spare left)
~ # cat /proc/acpi/battery/BAT1/state
present: yes
capacity state: ok
charging state: charged
present rate: 0 mA
remaining capacity: 4424 mAh
present voltage: 16517 mV

If all else fails then a bridge rectifier and series cap driving a relay could press the power button for a second when mains comes on.
But modern laptops will run for hours with mains power down, so how long are your mains interruptions?