Harmonics in pole power transformers?

It's all in metal conduit, into and out of the box, all the way to the pumps. Has to be.

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.

What about audio? The transformer and all the rest must produce some hum and when the transformer dies I bet it sound different.

om

nfo

l-tester.html#resources

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.

You might see some E-fields on the surface.... (conduit dependent) some multi probe thing. Sounds like a science project. :^)

George H.

It'll be very faint, the transformer is 100ft or more away (not an allowed site to install anything there) and there can be lots of other noise muffling such faint sounds.

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.

We'll certainly try everywhere, not just at the breaker box.

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?"

An all-electronic meter with an inner shield, which is common, wouldn't leak much e or h field.

Well, don't make it too easy on us.

Why not a second level sensor? The pump might fail. The bottom line is water level.

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.

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.

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

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?

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.

Yeah, and if they're paying a visit they could as easily install a standard electical outlet for you to plug your alarm into.

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

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