The Smell of Molten Projects in the Morning

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Blackout

Some weeks ago Mary heard a loud bang just as the lights went out. Central Hudson crews arrived shortly thereafter and began examining the transformer serving the group of houses around us. I wandered over to ask questions and learned the bang came from a high-voltage fuse atop a pole 800 feet from our house.

With all the power cables underground, the crews were locating the transformer just upstream of the problem, with the intent of disconnecting it and restoring power to everybody else. That took a few hours for our service, but folks up the hill remained in the dark maybe six more hours.

The paint on the transformer enclosures has been weathering for many decades, but I spotted this one up the hill that looks different from all the rest:

Scorched utility transformer housing
Scorched utility transformer housing

The scorched half of the enclosure pivots upward to reveal the high-voltage disconnect switch, fuses, and low-voltage connections. This one is across the street from our house:

Neighborhood distribution transformer
Neighborhood distribution transformer

I think something went badly wrong in there and the transformer overheated to the point of insulation failure, whereupon the short circuit blew the HV fuse half a mile away down the hill.

I hope it’s not the beginning of a trend …

Comments

6 responses to “Blackout”

  1. David Schultz Avatar
    David Schultz

    Those line fuses are pretty impressive. I remember watching a crew repair one once after lightning took it out.

    Using very long pole reach up and collect the fuse holder. It is on a pivot and when the fuse blows it swings down. Lower to ground, wrap new wire around, then raise up and hang in the pivot. The final step is to swing the holder back up into place.

    Accompanied by a brilliant flash and loud bang. Further inspection revealed that a loose bit of wire had fallen over the top of the transformer in just the right spot.

    Reply
    1. Ed Avatar
      Ed

      Although I went out to learn what was going on, I keep a respectful distance while they’re working.

      I prefer to have at least some scenery, if not the horizon, between me and any high-voltage action.

      Reply
  2. RCPete Avatar
    RCPete

    I’ve had the fuse running from the 12.5kV line to the house transformer blow. No dramatics except wondering what caused the failure. Our HV lines are above ground, but the 220 lines to the house are buried. Perhaps 300′ long, and I was sincerely hoping that the fault wasn’t in that line. (I don’t know if that section was in conduit or “securely” wrapped. Mid ’90s code allowed either.) Turns out, Pacific Power received a bad batch of service transformers in the 1990s. Mine went in 2012.

    That was entirely too interesting for my taste.

    Reply
    1. Ed Avatar
      Ed

      I think 12-ish kV runs from the far-off pole to the distribution transformers along the street. Judging from the length of the pole they use to yank the cylindrical HV fuse / disconnect out of the transformer panel before working on the low side, even the utility guys treat that much juice with considerable respect.

      They get gloved-hands-on with the mere 120 V down in the water-filled junction box, though.

      Reply
      1. RCPete Avatar
        RCPete

        In my brief stint as a firefighter (lordy, 20 years ago), we saw a video about a couple of guys who had too close an encounter with a 12.5kV line. They survived, but nobody wanted to eat anything for a few hours afterward.

        OTOH, I heard of a guy who ran a tool into a buried 12.5kV line. Apparently, beyond being thrown a few feet, he was relatively undamaged. shut down the job for a few hours, though.

        Reply
        1. Ed Avatar
          Ed

          “They survived” is one of those cases where the good news is that the bad news isn’t any worse. :ick:

          Reply

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