The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • Switchyard Hum

    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:

    Street View - 1 Sand Dock Rd
    Street View – 1 Sand Dock Rd

    The overall capacity is surely in the tens of megawatts and there’s an overwhelming hum coming down that driveway:

    Switchyard hum
    Switchyard hum

    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:

    Transformer hum
    Transformer hum

    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.