Forums

Mains fluctuations

Started by Don Y November 21, 2016
I notice, each morning, that several of the UPS's engage at nearly
identical times.  No visible dropouts (i.e., lights don't flicker).
UPS's claim either "distorted input" (which typically leads to a ~1 second
event) or "AVR" (which persists for 10-15 seconds at a time).

[The latter doesn't require the unit to switch to battery power]

The interesting thing is that it is "like clockwork".  E.g., I can
look at the clock and KNOW that the first even will be at 5:03A
(on this particular clock; of course, a man with more than one clock
never TRULY knows what time it is...)

So, guesses:  is this a supply issue (bringing more generating capacity
on-line or alternate sources to address the *expected* increase in demand)?
Or, is it a reflection of a sudden change in the load (all those folks
waking up and starting their day)?
On Monday, November 21, 2016 at 3:40:37 PM UTC-5, Don Y wrote:
> I notice, each morning, that several of the UPS's engage at nearly > identical times. No visible dropouts (i.e., lights don't flicker). > UPS's claim either "distorted input" (which typically leads to a ~1 second > event) or "AVR" (which persists for 10-15 seconds at a time). > > [The latter doesn't require the unit to switch to battery power] > > The interesting thing is that it is "like clockwork". E.g., I can > look at the clock and KNOW that the first even will be at 5:03A > (on this particular clock; of course, a man with more than one clock > never TRULY knows what time it is...) > > So, guesses: is this a supply issue (bringing more generating capacity > on-line or alternate sources to address the *expected* increase in demand)? > Or, is it a reflection of a sudden change in the load (all those folks > waking up and starting their day)?
No idea, but if it happens at about the same time every morning you could set up your 'scope to watch it as you have your coffee. Maybe you'll see something. George H.
On Mon, 21 Nov 2016 13:40:24 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>I notice, each morning, that several of the UPS's engage at nearly >identical times. No visible dropouts (i.e., lights don't flicker). >UPS's claim either "distorted input" (which typically leads to a ~1 second >event) or "AVR" (which persists for 10-15 seconds at a time). > >[The latter doesn't require the unit to switch to battery power] > >The interesting thing is that it is "like clockwork". E.g., I can >look at the clock and KNOW that the first even will be at 5:03A >(on this particular clock; of course, a man with more than one clock >never TRULY knows what time it is...) > >So, guesses: is this a supply issue (bringing more generating capacity >on-line or alternate sources to address the *expected* increase in demand)? >Or, is it a reflection of a sudden change in the load (all those folks >waking up and starting their day)?
Maybe the power company swapping in some extra capacity, with an amateur doing the phase matching >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I'm looking for work... see my website.
On 11/21/2016 2:34 PM, Jim Thompson wrote:
>> So, guesses: is this a supply issue (bringing more generating capacity >> on-line or alternate sources to address the *expected* increase in demand)? >> Or, is it a reflection of a sudden change in the load (all those folks >> waking up and starting their day)? > > Maybe the power company swapping in some extra capacity, with an > amateur doing the phase matching >:-}
That was my first thought (extra capacity in anticipation of the coming "morning load"). The "high line" conditions would also seem to confirm this. (OTOH, a big load dump could give similar results)
On 11/21/2016 2:07 PM, George Herold wrote:
>> So, guesses: is this a supply issue (bringing more generating capacity >> on-line or alternate sources to address the *expected* increase in demand)? >> Or, is it a reflection of a sudden change in the load (all those folks >> waking up and starting their day)? > > No idea, but if it happens at about the same time every morning you > could set up your 'scope to watch it as you have your coffee. > Maybe you'll see something.
I suspect that would just change the wording of my question -- to, "What would cause this sort of waveform?" :> Obviously, *something* is changing in the network. It seems easier to imagine that change being source driven instead of load driven ("OK, let's all agree to turn on our stoves at 5:03AM tomorrow morning!")
On 22/11/2016 07:40, Don Y wrote:
> I notice, each morning, that several of the UPS's engage at nearly > identical times. No visible dropouts (i.e., lights don't flicker). > UPS's claim either "distorted input" (which typically leads to a ~1 second > event) or "AVR" (which persists for 10-15 seconds at a time). > > [The latter doesn't require the unit to switch to battery power] > > The interesting thing is that it is "like clockwork". E.g., I can > look at the clock and KNOW that the first even will be at 5:03A > (on this particular clock; of course, a man with more than one clock > never TRULY knows what time it is...) > > So, guesses: is this a supply issue (bringing more generating capacity > on-line or alternate sources to address the *expected* increase in demand)? > Or, is it a reflection of a sudden change in the load (all those folks > waking up and starting their day)?
What system is used to switch off-peak loads and meter rates in your area? Historically a lot of areas used deliberate distortion of the mains, either with harmonics being injected, or IIRC sometimes big SCRs shorting the mains just before the zero crossing, or other stuff like that. Maybe they turn off all your neighbours' hot water heaters around 05:03? (In the UK they used a different system with a 198kHz over the air transmission.) e.g.: https://en.wikipedia.org/wiki/Zellweger_off-peak
On Mon, 21 Nov 2016 16:51:14 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>On 11/21/2016 2:34 PM, Jim Thompson wrote: >>> So, guesses: is this a supply issue (bringing more generating capacity >>> on-line or alternate sources to address the *expected* increase in demand)? >>> Or, is it a reflection of a sudden change in the load (all those folks >>> waking up and starting their day)? >> >> Maybe the power company swapping in some extra capacity, with an >> amateur doing the phase matching >:-} > >That was my first thought (extra capacity in anticipation of the >coming "morning load"). > >The "high line" conditions would also seem to confirm this. (OTOH, >a big load dump could give similar results)
When I look at our APC UPS log, you can see the Voltage Fluctuations in the morning and evening. It's probably a combination of both anticipation of supply demand and the increase of higher loads. Cheers
On 11/21/2016 2:40 PM, Don Y wrote:
> I notice, each morning, that several of the UPS's engage at nearly > identical times. No visible dropouts (i.e., lights don't flicker). > UPS's claim either "distorted input" (which typically leads to a ~1 second > event) or "AVR" (which persists for 10-15 seconds at a time). > > [The latter doesn't require the unit to switch to battery power] > > The interesting thing is that it is "like clockwork". E.g., I can > look at the clock and KNOW that the first even will be at 5:03A > (on this particular clock; of course, a man with more than one clock > never TRULY knows what time it is...) > > So, guesses: is this a supply issue (bringing more generating capacity > on-line or alternate sources to address the *expected* increase in demand)? > Or, is it a reflection of a sudden change in the load (all those folks > waking up and starting their day)?
Possibly putting power factor correction capacitors across the line?
On Monday, November 21, 2016 at 12:40:37 PM UTC-8, Don Y wrote:
> I notice, each morning, that several of the UPS's engage at nearly > identical times....
> The interesting thing is that it is "like clockwork". E.g., I can > look at the clock and KNOW that the first even will be at 5:03A
It happens here, too; a stereo that won't stay OFF (acts like the remote was used to turn it on) has been spontaneously turning on at odd intervals, but almost always within a few seconds of the hour. Three events took place at half-hour (7:30, 11:30, 7:30) times, three others took place at non-hour-aligned random times, and ten others at exact xx:00 times. So, the stereo is connected to a zeroed input signal, and I just let it stay on for now. Some kind of generator-coming-online or substation-switching scheduled event seems most likely. I thought, though, those were all carefully synchronized? Why would you lose even a half-cycle of power on such a switchover?
John S <Sophi.2@invalid.org> wrote:
> On 11/21/2016 2:40 PM, Don Y wrote: >> I notice, each morning, that several of the UPS's engage at nearly >> identical times. No visible dropouts (i.e., lights don't flicker). >> UPS's claim either "distorted input" (which typically leads to a ~1 second >> event) or "AVR" (which persists for 10-15 seconds at a time). >> >> [The latter doesn't require the unit to switch to battery power] >> >> The interesting thing is that it is "like clockwork". E.g., I can >> look at the clock and KNOW that the first even will be at 5:03A >> (on this particular clock; of course, a man with more than one clock >> never TRULY knows what time it is...) >> >> So, guesses: is this a supply issue (bringing more generating capacity >> on-line or alternate sources to address the *expected* increase in demand)? >> Or, is it a reflection of a sudden change in the load (all those folks >> waking up and starting their day)? > > Possibly putting power factor correction capacitors across the line? >
That sounds like the most likely explanation. Put the PFC capacitors in, then wait for voltage regulators to slowly bring the voltage back down.