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Harmonics in pole power transformers?

Started by Joerg April 17, 2016
Jasen Betts wrote:
> > On 2016-04-18, Joerg <news@analogconsultants.com> wrote: > > > > There is no room. Just that last pole, the transformer, a meter and > > breaker box and the pumps. Other than that maybe some cattle. > > > > We'd be counting on the ever so small leaking E-field because with the > > pumps turned off that's all there is going to be. Hence my question > > whether we could use harmonics to see a change versus the E-field coming > > from the distant HV line. The engineer taking care of the software side > > is very good at extracting signature signals to hear "the grass grow". > > > > What triggers the pump? is there a 4-20mA loop, 24VAC circuit, or some other > ELV sensor? that voltage/current will likelly go away when the mains fails. > > hmm, probably 240V float switch... bummer.
A float switch on a well pump? All I have ever seen use a mechanical pressure sensing switch that turns on when the pressure drops below the setpoint, and turns off when the maximum is reached. The one on my well was 22 years old, when the well failed. A second switch can be plumbed in, and used to control a transmitter. Determine how long it normally takes to restore full pressure, and use a timer to delay the signal. If you are terrified of touching the wiring, use a solar powered battery charger. I can't see why anyone would install an electric powered well pump without a service outlet, unless they are just too damned cheap. There is a housing over my tank, with a thermostat to run a heater if it drops to 35&#2013266096; F. A small breaker box is inside the housing, to allow me to troubleshoot the pump, or to turn it off if I will be away for an extended time. I had a nearly blind neighbor try to be helpful once. He mowed the grass while I was gone, and sheared off an outdoor faucet. That left the pump running for days, and ran up the electric bill. The upgrades will prevent that. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
On 2016-04-19 07:01, John Larkin wrote:
> On Tue, 19 Apr 2016 03:20:21 -0700 (PDT), jrwalliker@gmail.com wrote: > >> On Tuesday, 19 April 2016 00:28:40 UTC+1, Joerg wrote: >>> On 2016-04-18 14:58, George Herold wrote: >> >>>> Joerg, (perhaps a stupid question.) >>>> But if there's no, or very little, current flowing why >>>> will there be much B-field? (and any saturation.) >> >>> John was hinting that a meter might radiate enough magnetic energy. But >>> not sure if smart meters also would. >> >> Rotating disc meters are analogue multipliers with a current and a >> voltage winding. The voltage winding is always energised, so there >> will always be leakage flux, especially near the gap in the magnetic >> circuit where the disc intersects the gap in the core. This is >> often at the front, just behind the glass window. >> >> The smart meters that I know about (having had a tour of the production >> line and development lab of a well known manufacturer) have a manganin >> sense resistor with an op-amp to measure the voltage drop across it. >> There is nothing that will give a large leakage flux when no current >> is being drawn. However, they do usually have a flashing red LED and >> this will indicate that there is power as long as a small load current >> is present. >> >> John >> > > Some smart meters still have the disc mechanism. It's amazingly > accurate and rugged and cheap. > >
That's the problem, too much product variation in the field. For example, our smart meter does not have a flashing LED. I think we'll have to make do with 60Hz. -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-19 07:04, Michael A. Terrell wrote:
> > Jasen Betts wrote: >> >> On 2016-04-18, Joerg <news@analogconsultants.com> wrote: >>> >>> There is no room. Just that last pole, the transformer, a meter and >>> breaker box and the pumps. Other than that maybe some cattle. >>> >>> We'd be counting on the ever so small leaking E-field because with the >>> pumps turned off that's all there is going to be. Hence my question >>> whether we could use harmonics to see a change versus the E-field coming >>> from the distant HV line. The engineer taking care of the software side >>> is very good at extracting signature signals to hear "the grass grow". >>> >> >> What triggers the pump? is there a 4-20mA loop, 24VAC circuit, or some other >> ELV sensor? that voltage/current will likelly go away when the mains fails. >> >> hmm, probably 240V float switch... bummer. >
The setup very different between locations. We cannot rely on any of that.
> > A float switch on a well pump? All I have ever seen use a mechanical > pressure sensing switch that turns on when the pressure drops below the > setpoint, and turns off when the maximum is reached. The one on my well > was 22 years old, when the well failed. A second switch can be plumbed > in, and used to control a transmitter. Determine how long it normally > takes to restore full pressure, and use a timer to delay the signal. If > you are terrified of touching the wiring, use a solar powered battery > charger. I can't see why anyone would install an electric powered well > pump without a service outlet, unless they are just too damned cheap. > There is a housing over my tank, with a thermostat to run a heater if it > drops to 35&#2013266096; F. A small breaker box is inside the housing, to allow me > to troubleshoot the pump, or to turn it off if I will be away for an > extended time. I had a nearly blind neighbor try to be helpful once. He > mowed the grass while I was gone, and sheared off an outdoor faucet. > That left the pump running for days, and ran up the electric bill. The > upgrades will prevent that. >
You don't have to be blind for that. Our neighbors in Germany, after half an our of lawnmower din: "Peter, those were not weeds! They were my carnations!" [...] -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-18 17:44, John Larkin wrote:
> On Mon, 18 Apr 2016 16:31:39 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2016-04-18 14:50, whit3rd wrote: >>> On Monday, April 18, 2016 at 8:02:21 AM UTC-7, Joerg wrote: >>>> On 2016-04-18 07:48, Phil Hobbs wrote: >>> >>>>> I'd be wanting to move the goal posts and cycle the pump every few hours >>>>> just to make sure. >>> >>>> We can't. It's all automatic and often legacy equipment that some might >>>> even call pre-historic. >>> >>> Just for giggles: is there a meter on these drops? A smart meter, that takes >>> 3W all the time, that has wireless reporting back to the utility? If you >>> could read out the meter, it'd solve the problem instantly. >>> >> >> Can't rely on that, we have to cover all situations. Many places will >> still have analog meters, some may not have meters at all and instead >> pay a flat rate. Or they are on a company/farm grid where there is no >> need for metering. > > Well, don't make it too easy on us. >
I love those kinds of jobs where you have next to nothing to use as input and you have to make it work anyhow. -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-18 17:48, John Larkin wrote:
> On Mon, 18 Apr 2016 16:32:52 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2016-04-18 15:02, Lasse Langwadt Christensen wrote: >>> Den mandag den 18. april 2016 kl. 23.50.56 UTC+2 skrev legg: >>>> On Mon, 18 Apr 2016 07:58:30 -0700, Joerg <news@analogconsultants.com> >>>> wrote: >>>> >>>>> On 2016-04-18 07:57, legg wrote: >>>>>> On Sun, 17 Apr 2016 17:16:12 -0700 (PDT), George Herold >>>>>> <gherold@teachspin.com> wrote: >>>>>> >>>>>>> On Sunday, April 17, 2016 at 4:54:36 PM UTC-4, Joerg wrote: >>>>>>>> Folks, >>>>>>>> >>>>>>>> A system needs to be able to detect whether a pole transformer has >>>>>>>> failed and stopped feeding power to a pump. The transformer will be >>>>>>>> 100ft or more away. The detection has to work even without any power >>>>>>>> flow meaning we can only detect the presence of a 60Hz electric field >>>>>>>> that leaks from the various boxs such as a breaker box. >>>>>>>> >>>>>>>> In order not to get fooled by 60Hz from other overhead lines I was >>>>>>>> wondering if classic pole transformers generate enough 3rd and 5th >>>>>>>> harmonics to distinguish the field emanating from secondary wires from >>>>>>>> that coming from overhead HV lines. Does anyone know where to find info >>>>>>>> about that? >>>>>>>> >>>>>>>> -- >>>>>>>> Regards, Joerg >>>>>>>> >>>>>>>> http://www.analogconsultants.com/ >>>>>>> >>>>>>> Magneto-striction causes the transformer to vibrate at 120 Hz, >>>>>>> I don't know if you could sense that. >>>>>>> >>>>> >>>>> Audio buzz isn't reliable here because the transformer will be far away. >>>>> All we have is any E-field leaking out from conduit and the breaker box. >>>>> The good thing is, we can be right at the breaker box, just not in it. >>>>> >>>>> >>>>>>> George H. >>>>>> >>>>>> Transformers can fail and still buzz. >>>>>> >>>>>> There are many reasons why a pump might fail. Expending effort at >>>>>> sensing just a single one of these is misdirected. >>>>>> >>>>> >>>>> No, it is not. The fact that transformer or HV line failure is by far >>>>> the highest concern in this application is based on clear statistical >>>>> evidence. >>>>> >>>> I'd like to see THOSE statistics. >>>> >>>> You're trying to see if a pump is functional, when it's not supposed >>>> to be running. Does this make sense to you? >>> >>> if it is, say, a pump to keep a basement from flooding or some cows from >>> going thirsty it makes perfect sense to get an electrician out to fix the >>> power before it is needed >>> >> >> Bingo! > > Why not a second level sensor? The pump might fail. The bottom line is > water level. >
There are already provisions to detect a pump failure. The goal is to find out what failed. Pump damage means their own guys or a contractor has to drive out. Mains failure before the panel means they have to call the utility instead. Having the wrong crew arrive carries a large cost. The end customers don't want to pay more for a more distinct failure report than they have to. -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-19 03:07, Jasen Betts wrote:
> On 2016-04-18, Joerg <news@analogconsultants.com> wrote: >> On 2016-04-18 09:41, Adrian Tuddenham wrote: >>> Joerg <news@analogconsultants.com> wrote: > >> That would require an electrician to come out and most would refuse this >> job because they, their employer or their union won't allow non-standard >> stuff. > > Yeah, and if they're paying a visit they could as easily install a > standard electical outlet for you to plug your alarm into. >
The trick is to be able to install this without that truck roll. Because such a truck roll would increase the cost per install by several hundred Dollars, considering travel charges. -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-18 17:17, whit3rd wrote:
> On Monday, April 18, 2016 at 4:38:12 PM UTC-7, Joerg wrote: > >> The goal is to have a single self-contained "sniffer box", no wires, >> nothing going in and out in terms of connections. > > If nothing goes out, you never get any information, of course... > which simplifies the 'sniffer' function, you just drop that requirement. > > If you can't standardize on a meter that has reporting, or wire a > reporting relay inside a breaker box, or depend on a noisy or light-emitting > or signal-flag-waving bit of driven apparatus, the power from that > pole pig transformer is only a potential, not an action with consequences. > I'm dubious that the potential alone, within "a metal enclosure", is > something that can be reliably sensed from without. >
Yes, like "Mixed Nuts" (Or Grizzly H.?) wrote the E-field will be very paltry. But we'll have to try. -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-18 19:58, legg wrote:
> On Mon, 18 Apr 2016 16:38:44 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2016-04-18 15:53, legg wrote: >>> On Sun, 17 Apr 2016 13:55:05 -0700, Joerg <news@analogconsultants.com> >>> wrote: >>> >>>> Folks, >>>> >>>> A system needs to be able to detect whether a pole transformer has >>>> failed and stopped feeding power to a pump. The transformer will be >>>> 100ft or more away. The detection has to work even without any power >>>> flow meaning we can only detect the presence of a 60Hz electric field >>>> that leaks from the various boxs such as a breaker box. >>>> >>>> In order not to get fooled by 60Hz from other overhead lines I was >>>> wondering if classic pole transformers generate enough 3rd and 5th >>>> harmonics to distinguish the field emanating from secondary wires from >>>> that coming from overhead HV lines. Does anyone know where to find info >>>> about that? >>> >>> You should be able to differentiate the ambient field from near-field >>> using two sensors, regardless of their content. >>> >> >> Sure, but then we have the same situation as we would if sticking a 2nd >> sensor unit inside the panel next to a breaker with a radio repeater on >> the outside: The need to ship two units -> $$$. >> >> The goal is to have a single self-contained "sniffer box", no wires, >> nothing going in and out in terms of connections. > > I'm sorry, but you made this sound like you needed some kind of > portable instrument, with no prepared access to anything but the > surrounding air. > > If you're able to install fixed hardware, then I really don't see your > problem except that you don't want to use conventional sensors. >
No install possible. All we can do is supply a little unit with instructions "Stick this to the XYZ box in the upper left corner and wait until it beeps three times". -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-18 18:55, Ralph Barone wrote:
> Joerg <news@analogconsultants.com> wrote: >> Folks, >> >> A system needs to be able to detect whether a pole transformer has >> failed and stopped feeding power to a pump. The transformer will be >> 100ft or more away. The detection has to work even without any power >> flow meaning we can only detect the presence of a 60Hz electric field >> that leaks from the various boxs such as a breaker box. >> >> In order not to get fooled by 60Hz from other overhead lines I was >> wondering if classic pole transformers generate enough 3rd and 5th >> harmonics to distinguish the field emanating from secondary wires from >> that coming from overhead HV lines. Does anyone know where to find info >> about that? >> > > I would assume that your classic "pole pig" uses similar iron to its big > brother in the substation, and that it works at a similar flux density, > therefore your proposal is likely to translate to "you can't get there from > here". >
Well, I was hoping the substation transformers were much better because there is not as much cost and size per kW pressure as with pole pigs. But maybe that isn't the case. We shall see, only experiments will tell, it seems.
> Why not just build your box to memorize the EMC environment when it is > first turned on and compare to that. Then all you need is an instruction to > not install your box on a dead circuit. >
That's what we'll do anyhow. But the fields from the power lines can change in many locations even without faults. Swaying vegetation, animals, precipitation, vehicle traffic and so on. -- Regards, Joerg http://www.analogconsultants.com/
On 2016-04-18 23:16, DAB wrote:
> Piezo electric accelerometer outside the box sensing 60Hz vibration when > the current is flowing in the xformer? >
That would work but utilities frown very much upon non-employees climbing up a pole and sticking something to a transformer. Especially these days.
> > On 18-Apr-16 4:55 AM, Joerg wrote: >> Folks, >> >> A system needs to be able to detect whether a pole transformer has >> failed and stopped feeding power to a pump. The transformer will be >> 100ft or more away. The detection has to work even without any power >> flow meaning we can only detect the presence of a 60Hz electric field >> that leaks from the various boxs such as a breaker box. >> >> In order not to get fooled by 60Hz from other overhead lines I was >> wondering if classic pole transformers generate enough 3rd and 5th >> harmonics to distinguish the field emanating from secondary wires from >> that coming from overhead HV lines. Does anyone know where to find info >> about that? >> >
-- Regards, Joerg http://www.analogconsultants.com/