3 ms·

A misplaced wire label caused a power outage on a container ship, the NTSB finds

6 points by mschuster91 1y ago

ghostly_s 1y ago
I don't follow how the label placement in the graphic could cause a connection issue, unless it slipped down further to interfere with the pin?
- rolph 1y ago
  that is very much the primary event. "That sticker, identifying the line, kept the wire from getting a good connection in a circuit breaker – which in turn ultimately caused the first blackout. "
eternityforest 1y ago
They say thermal imaging could have identified the issue, does that mean that it was actually a low voltage power line, not a signal line? Do they have cameras that can see the heat from sub-mA connections? I wonder what kind of diagnostics and logging they have for their power distribution?
- mikewarot 1y ago
  > Do they have cameras that can see the heat from sub-mA connections? If it was hooked to a circuit breaker, it wasn't a sub milliamp connection. A thermal camera might have been able to see the heat from arcing at the connection point. It could have caused a hot spot visible on thermal imaging.
  - eternityforest 1y ago
    The article claims it's a "low voltage signal wire", but perhaps they meant to say a low voltage power wire?
    - mikewarot 1y ago
      According to the report, on page 7[1], it was connected to a WAGO terminal block 280-681 connector. Looking that up on Digikey[2,3] finds that it's a connector suitable for 28 through 12 AWG, up to 800 volts and 24 amps.(UL 20 Amps) According to "3 - ENGINEERING - DALI - ENGINEERING FACTUAL REPORT"[5], page 20, the circuit was DC, 110 volts, going to a circuit breaker's "under voltage release" terminal. It was 17 AWG, according to page 23. It apparently goes to a solenoid, and if [6] is in any way typical, it's only 2-6 watts of power in normal operation. This yields a current of 20-50 milliAmps. Here's a nice animation of the connection failure on that wire.[4] [1] https://www.ntsb.gov/investigations/Documents/Board%20Summary%20Contact%20of%20Containership%20Dali%20with%20Francis%20Scott%20Key%20Bridge.pdf https://www.ntsb.gov/investigations/Documents/Board%20Summar... [2] https://www.digikey.com/en/products/detail/wago-corporation/280-681/13549659 https://www.digikey.com/en/products/detail/wago-corporation/... [3] https://wago.priintcloud.com/datasheets/280-681/en_GG/d41d8cd98f00b204e9800998ecf8427e?attempt=1&signature=d4308f072daccce5371849c553978cc3_1iespcbe7 https://wago.priintcloud.com/datasheets/280-681/en_GG/d41d8c... [4] https://www.youtube.com/watch?v=bu7PJoxaMZg https://www.youtube.com/watch?v=bu7PJoxaMZg [5] https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&FileExtension=pdf&FileName=DALI%20-%20DCA24MM031%20-%20Engineering%20-%20Factual%20Report%20-%20FINAL-Rel.pdf https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&Fi... [6] https://abbsales.com/pdfs/tmax_techspecs.pdf https://abbsales.com/pdfs/tmax_techspecs.pdf
      - eternityforest 1y ago
        Wow, that's a lot of amazing information, so many details that just get glossed over if you don't read the full report!
FrankWilhoit 1y ago
If it happened, it wasn't preventable. If you say it was preventable, you mean that in theory, it could have been prevented by people who don't exist (front-line and management, with consciences), working processes that don't exist, using resources that don't exist, within cultures that don't exist.
mikewarot 1y ago
The actual discovery of the wiring problem is pretty interesting. It starts on page 17 of the Engineering Factual Report[1], which is one of many released[2]. The wire in question was carrying unknown current (likely 20-50 mA), but 110 volts DC signaling. Comparing the photos on page 22 (Dali) and 25 (Cezanne), you can clearly see the blue ferrules in the correctly wired panel on the Cezanne. [1] https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&FileExtension=pdf&FileName=DALI%20-%20DCA24MM031%20-%20Engineering%20-%20Factual%20Report%20-%20FINAL-Rel.pdf https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&Fi... [2] https://data.ntsb.gov/Docket/?NTSBNumber=DCA24MM031 https://data.ntsb.gov/Docket/?NTSBNumber=DCA24MM031
gregsadetsky 1y ago
Related discussion: https://news.ycombinator.com/item?id=45984659 https://news.ycombinator.com/item?id=45984659

6 points by mschuster91 1y ago

I don't follow how the label placement in the graphic could cause a connection issue, unless it slipped down further to interfere with the pin?

rolph 1y ago
that is very much the primary event. "That sticker, identifying the line, kept the wire from getting a good connection in a circuit breaker – which in turn ultimately caused the first blackout. "

eternityforest 1y ago

They say thermal imaging could have identified the issue, does that mean that it was actually a low voltage power line, not a signal line? Do they have cameras that can see the heat from sub-mA connections? I wonder what kind of diagnostics and logging they have for their power distribution?

mikewarot 1y ago
> Do they have cameras that can see the heat from sub-mA connections? If it was hooked to a circuit breaker, it wasn't a sub milliamp connection. A thermal camera might have been able to see the heat from arcing at the connection point. It could have caused a hot spot visible on thermal imaging.
- eternityforest 1y ago
  The article claims it's a "low voltage signal wire", but perhaps they meant to say a low voltage power wire?
  - mikewarot 1y ago
    According to the report, on page 7[1], it was connected to a WAGO terminal block 280-681 connector. Looking that up on Digikey[2,3] finds that it's a connector suitable for 28 through 12 AWG, up to 800 volts and 24 amps.(UL 20 Amps) According to "3 - ENGINEERING - DALI - ENGINEERING FACTUAL REPORT"[5], page 20, the circuit was DC, 110 volts, going to a circuit breaker's "under voltage release" terminal. It was 17 AWG, according to page 23. It apparently goes to a solenoid, and if [6] is in any way typical, it's only 2-6 watts of power in normal operation. This yields a current of 20-50 milliAmps. Here's a nice animation of the connection failure on that wire.[4] [1] https://www.ntsb.gov/investigations/Documents/Board%20Summary%20Contact%20of%20Containership%20Dali%20with%20Francis%20Scott%20Key%20Bridge.pdf https://www.ntsb.gov/investigations/Documents/Board%20Summar... [2] https://www.digikey.com/en/products/detail/wago-corporation/280-681/13549659 https://www.digikey.com/en/products/detail/wago-corporation/... [3] https://wago.priintcloud.com/datasheets/280-681/en_GG/d41d8cd98f00b204e9800998ecf8427e?attempt=1&signature=d4308f072daccce5371849c553978cc3_1iespcbe7 https://wago.priintcloud.com/datasheets/280-681/en_GG/d41d8c... [4] https://www.youtube.com/watch?v=bu7PJoxaMZg https://www.youtube.com/watch?v=bu7PJoxaMZg [5] https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&FileExtension=pdf&FileName=DALI%20-%20DCA24MM031%20-%20Engineering%20-%20Factual%20Report%20-%20FINAL-Rel.pdf https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&Fi... [6] https://abbsales.com/pdfs/tmax_techspecs.pdf https://abbsales.com/pdfs/tmax_techspecs.pdf
    - eternityforest 1y ago
      Wow, that's a lot of amazing information, so many details that just get glossed over if you don't read the full report!

FrankWilhoit 1y ago

If it happened, it wasn't preventable. If you say it was preventable, you mean that in theory, it could have been prevented by people who don't exist (front-line and management, with consciences), working processes that don't exist, using resources that don't exist, within cultures that don't exist.

mikewarot 1y ago

The actual discovery of the wiring problem is pretty interesting. It starts on page 17 of the Engineering Factual Report[1], which is one of many released[2]. The wire in question was carrying unknown current (likely 20-50 mA), but 110 volts DC signaling. Comparing the photos on page 22 (Dali) and 25 (Cezanne), you can clearly see the blue ferrules in the correctly wired panel on the Cezanne. [1] https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&FileExtension=pdf&FileName=DALI%20-%20DCA24MM031%20-%20Engineering%20-%20Factual%20Report%20-%20FINAL-Rel.pdf https://data.ntsb.gov/Docket/Document/docBLOB?ID=19228257&Fi... [2] https://data.ntsb.gov/Docket/?NTSBNumber=DCA24MM031 https://data.ntsb.gov/Docket/?NTSBNumber=DCA24MM031

gregsadetsky 1y ago

Related discussion: https://news.ycombinator.com/item?id=45984659 https://news.ycombinator.com/item?id=45984659