For reasons not relevant here, I walked along IBM Rd to the end of Sand Dock Rd and back, passing the switchyard serving the IBM Poughkeepsie site:
The overall capacity is surely in the tens of megawatts and there’s an overwhelming hum coming down that driveway:
Those peaks and the corresponding lines in the waterfall show the equipment emits acoustic energy all the way up to about 480 Hz, call it the eighth harmonic of 60 Hz.
Transformer steel has low magnetostriction, which produces most of the noise at even harmonics of the 60 Hz power line (because each cycle has two current maxima). The spectrogram shows the switchyard handles enough current to emit plenty of odd harmonic energy, with a notable peak at 180 Hz.
For comparison, standing a few feet from the transformer behind a medical office building along IBM Rd:
No 180 Hz energy from that transformer!
Moving a few feet further away dropped those peaks into the background.
Even with my deflicted ears, I think can hear the switchyard hum from a considerable distance along the road, so maybe the background isn’t as quiet as I think.
The Smell of Molten Projects in the Morning 
Comments
5 responses to “Switchyard Hum”
I wonder if the 180Hz harmonics are due to it being three phase power.
Good point, particularly because the small office-building transformer is (almost certainly) not three-phase.
You’re probably getting a dose of the fan cooling noise, so that’s where the broadband is coming from. It also looks like there’s some other interesting equipment in the Barnegat Substation, so there could be inverters with all of their fun noises (and cooling)
I’ve always been tempted to stick my nose up against that kind of fence just to see what’s inside, but in this day & age it’s a Really Bad Idea.
The sound is clearly audible from Barnegat Rd, maybe 500 feet away, so there’s plenty of energy in the air!
I would totally stick my nose up against that fence … but then, I’ve operated switchyards and generating plant*. There are usually signs on the fence saying what it is. If there’s a crew there and they’re outside the gate, go ask ’em. Everything that’s in there was permitted and is regulated by a public process, so if you had all the time in the world and a certain bloody-minded streak, you could find out what it is. But life’s too short for that, and if there’s people to talk to, they’ll usually help.
One thing – which I know you wouldn’t do – don’t go in the gate if it’s open. It’s on a 115 kV line. Those are the extra-pointy volts.
If the noise from the facility is a problem for you or your neighbours, let the utility know. It’s their job not to annoy you.
*: okay, it was small stuff: 10 MW wind farms by Lake Erie, but it was still connecting to 40 kV