Forums

Harmonics in pole power transformers?

Started by Joerg April 17, 2016
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. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 4/18/2016 8:19 PM, Joerg wrote:
> On 2016-04-18 17:10, George Herold wrote: >> On Monday, April 18, 2016 at 7:35:41 PM UTC-4, Joerg wrote: >>> On 2016-04-18 14:56, Lasse Langwadt Christensen wrote: >>>> Den mandag den 18. april 2016 kl. 23.38.08 UTC+2 skrev Joerg: >>>>> On 2016-04-18 14:19, Lasse Langwadt Christensen wrote: >>>>>> Den s&#2013266168;ndag den 17. april 2016 kl. 22.54.36 UTC+2 skrev >>>>>> Joerg: >>>>>>> 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? >>>>>>> >>>>>>> http://www.analogconsultants.com/ >>>>>> >>>>>> electrical-testers/fluke-2ac-electrical-tester.html >>>>>> >>>>> http://en-us.fluke.com/products/electrical-testers/fluke-2ac-electrical-tester.html#resources >>>>> >>>>> It doesn't let me download the manual but from the pictures >>>>> it looks like you need to be closer than an inch. >>>>> >>>> can't find any mention of distance it is probably a liability >>>> thing. >>>> >>>> don't the wires come out of the box so you can easily get >>>> close? >>>> >>> It's all in metal conduit, into and out of the box, all the way >>> to the pumps. Has to be. >>> >> OK... well now I see the problem. Can I stick probes into the >> surface of the conduit? Never mind the E-fields don't make it to >> the surface. >> > We'll certainly try everywhere, not just at the breaker box. > >> You might see some E-fields on the surface.... (conduit dependent) >> some multi probe thing. Sounds like a science project. :^) >> > It sure will be one and we are prepared for that. The problem will be > to test the alert case. "Hey, you, would you mind climbing up that > pole and opening the big fuse once more?"
You can get squirrels that do that - had it happen here a couple of times. One took out a substation that fed 1/2 a dozen towns, a couple others took out the transformer fuse in front of my house and another about a mile up the road. It seems unlikely that you'll find an easy way to measure the e-field on the secondary side. However, with 10KV on the overhead wires (about 1 meter apart?), there'll be a voltage gradient at ground level (about 10 meters away?) that should be in the range of several volts/meter. All you need is a dipole antenna (a tiny fraction of a wavelength so it appear as a very high impedance at the center) with an amplifier to drive a shielded cable to your measuring system. You can also measure current (should there be any) as a b-field gradient as an induced voltage with a pair of loops in antiphase placed near the e-field dipole. You won't know explicitly that the secondary fuse is good, but you should be able to see the pump or any other load cycling. -- Grizzly H.
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". 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.
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. RL
On Mon, 18 Apr 2016 15:02:07 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> 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 > >-Lasse
I'm not convinced any of this makes sense, transformer reliability being what it is. Failure in HV lines brings a subscriber's electrician to the rescue? Give me a break. RL
Piezo electric accelerometer outside the box sensing 60Hz vibration when 
the current is flowing in the xformer?


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? >
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. -- \_(&#12484;)_
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
On Mon, 18 Apr 2016 07:47:30 -0700, Joerg <news@analogconsultants.com>
wrote:

>On 2016-04-17 15:48, Martin Riddle 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? >> >> Hmmm, I constructed a Tone probe using a LM386 as the receiver. It >> does a good job at pickingup 60 hz Hum. Maybe that loosly coupled with >> the AC input of the pump and a 555 as a missing pulse detector would >> work. >> > >Tone probe would be one of my ideas as well. I'd have top find some >cheap and most of all small IC that fishes out 60Hz plus maybe 180Hz. >We've got a uC and ADC but it might become overwhelmed with all the >other noise if there isn't at least some filtering. Passive filtering is >out because of the inductor sizes. Oh, and it has to literally sip >power, micro amps.
A suiside stick, like the FLIR VP50 mounted in the breaker cover. I dont know the distances involved to trigger those things. But as long as the cover is closed... Cheers
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. -- John Larkin Highland Technology, Inc lunatic fringe electronics