@restorer-john what do you attribute this hummmm to? I think if the power line is active as in in-service then they must maintain ground reference albeit at a lower power rating.
The story of the 3 large size audio transformers used in the 1960s MCIntosh power amplifiers (e.g. MC275) were potted with a compound that contained nasty (carcinogen?) chemicals used to prevent any 60Hz hum caused by the close-coupled winding that may vibrate... One of the reason that was cited (as I recall) for their discontinuation. In the early 1980s, McIntosh broke the news that a pallet of these transformers where found in some warehouse and that they would make a limited quantity of SeriesII MC275s....Use a transformer to obtain mains,...
Fascinating stuff for sure. Is this something you worked on with the 400 Hz mains?The story of the 3 large size audio transformers used in the 1960s MCIntosh power amplifiers (e.g. MC275) were potted with a compound that contained nasty (carcinogen?) chemicals used to prevent any 60Hz hum caused by the close-coupled winding that may vibrate... One of the reason that was cited (as I recall) for their discontinuation. In the early 1980s, McIntosh broke the news that a pallet of these transformers where found in some warehouse and that they would make a limited quantity of SeriesII MC275s.
While working for on some military ship-borne massive communication suite, the 400Hz power required for energizing parts of the RF power systems in a shielded chamber, the needed MAINS' power-factor correction coils that were mechanically/galvanically isolated from the chamber but would sing so loud (~102dB/A), live qualification testing could only be achieved after-hours and the technicians (w/headphones) were only allowed to stay in the SCIF labs for no more than 4 hours per day.
That 400Hz hum continued for three months straight, but we were lucky no one had gone postal on us!
What do you mean by 'all around the neighborhood'?I continue to be plagued with an ever present 120 Hz, ambient, hum of unvarying loudness inside and outside my new house and , indeed, all around the neighborhood. Flipping off the main circuit breaker to my house does not change this in any way.
I'm left with the theory that this is mains hum originating in the power lines around my house and throughout the neighborhood.
? Wouldn't "improperly installed powerlines" cause 'noise' (arc/spark) rather than "hum"?It's possible the power lines were never installed properly...
Maybe walk around the neighborhood in a grid pattern recording the volume of the hum to help locate the source. Correlate to location with GPS.So so-called ‘hum’ that plagues people world wide seems to be around 40-50 hz. 120 hz has to be related to the 60 hz grid somehow. But why 120 and not 60 is even more curious.
I have never heard of (or seen) above-ground powerlines which showed to be 'vibrating' at frequency-of-operation or its harmonics... but I don't get out much anymore.
Why do power lines buzz?
When near high tension power lines, particularly after a good rain, the lines themselves emit a buzzing noise. A similar noise can be heard coming out of the electric meters attached to my apartmen...physics.stackexchange.com
Why does electricity hum -- and why is it a B flat in the US, and a G in Europe?
Who knew sound and current can intertwine so much?www.zmescience.com
JSmith
No but things that use transformers have similar issues. Shut all breakers off and then turn them on one by one only to see if it is a isolated issue.Interesting. Would the hum be present even with the lights turned off?
Thank you for the articles but both are quite hard to swallow (as explanatory), yet some included factoids are valid.JSmith
No, @Timcognito, it is not what a GroundFaultInterrupter does either! Literal or figurative.Everything off where is it coming from, the air?
I've often heard hum/buzz from HV power lines. Actually from the pylons rather than the lines.? Wouldn't "improperly installed powerlines" cause 'noise' (arc/spark) rather than "hum"?
I have never heard of (or seen) above-ground powerlines which showed to be 'vibrating' at frequency-of-operation or its harmonics... but I don't get out much anymore.
Trying to find the location of the transformer(s) serving the community's powerlines may lead to a missing clue. ymmv
FWIW: Someone did the math, already:I've often heard hum/buzz from HV power lines. Actually from the pylons rather than the lines.
It would not be a big surprise if the magnetic field generated by up to 4000A moved some stuff at mains frequency.
Is this more plausible than the catfish?This is the only explanation I can think off : Lorentz force due to earth's magnetic field
Let's do a rough estimation:
Let's say we have some power line at 1000A (should be ok for 100mm^2 wire), 200 meters between towers.
F=200 meters * 1000A * 40 microteslas (some average Earth's magnetic field) = 8 newtons (Not looking at angle at the moment, depend on position & location)
While 8 newtons itself is not much to significantly move heavy wires at 50/60 hertz (this sample wire would weight ~180kg), if line have any mechanical resonance at multiple of 50/60 hertz, vibration will amplify and will be significant to make audible sound.
From <https://physics.stackexchange.com/questions/12629/why-do-power-lines-buzz>
Exactly! That's the thing that's driving me batty. What's the source of this hum?? My wife hears it too so it's not my tinnitis or one sided hearing loss. In fact, my hearing problems exacerbate my already acute sensitivity to background noises of all sorts, hums, autos, sirens, airplanes, etc., etc. And, as I said, when I walk down to the end of my street or anywhere else in my neighbohood, if the ambient noises are relatively low, there's the hum.Everything off where is it coming from, the air?