https://www.ntsb.gov/investigations/Pages/DCA24MM031.aspx
So, a loose wire?
New thread:
An undervoltage release is basically a small electromagnet which must be powered permanently to keep a breaker closed.
If for any reason the control voltage drops below some limit even during a short time (typically under 0.1 second, i.e. 100 ms), the breaker trips.
See my messages in the specific topic linked by Kennebec_Captain above for more technical details.
A breaker is like a very large remotely operated switch which main contacts can be either open (current cannot flow due to the galvanic separation) or closed (current can flow).
Using an undervoltage release instead of much more common redundant shunt trip releases (two independent shunt trip releases with individual coil monitoring) can be considered as a major design flaw, even 10 or 20 years ago.
This design error is based either on a flawed probabilistic risk assessment… or on stupidity.
Or possibly some blind copy/pasting from a design where such release was indeed required (e.g. some dangerous machines with large motors but than you need two breakers in series).
With an undervoltage release as used for HR1 (Fig. 5 PR (Preliminary Report)) already very short (less than 100 milliseconds (1/10 s)) voltage dips in the control voltage of the undervoltage release can lead to a spurious trip.
Also undervoltage releases can be more sensitive to shocks than shunt releases though that depends on the breaker design.
The usual practice to open breakers relies on shunt releases (shunt trip coils) which only need to be shortly energized (typically 100 ms is long enough) when a breaker must trip.
With two redundant shunt trip coils and individual coil monitoring, the probability that a breaker cannot be tripped is very low and indeed other failures become more probable than an undetected failure of both shunt releases.
With any undervoltage release, the slightest continuity issue in the wiring can lead to a spurious trip, as it was the case as HR1 tripped and caused the first Low Voltage (LV, 440 V AC 50 Hz) blackout (LV BUS, the HV (High Voltage, 6’600 V AC, 50 Hz) BUS was unaffected as it remained powered without any interruption until the second blackout which occurred as both DGR3 and DGR4 tripped for unspecified reasons).
In comparison, with dual shunt releases the first wiring interruption will be detected and lead to an alarm while the 2nd shunt release will still work normally (it is unlikely that with a well designed wiring both trip solenoids will become inoperative, though ship wiring is not always well thought, often to save tiny amounts of money).
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Personally I had way more issues with screwless terminals, regardless of their respective manufacturers, than with good screw terminals but opinions widely vary and there have been endless discussions about screw vs. screwless terminals.
Screwless terminals for small cross sections can resist better to vibrations but they must be handled correctly, for larger cross sections I do not trust any screwless terminal and even less for PE.
Many issues are related to modifications and troubleshooting, especially as screwless connection systems are more likely to cause undetected problems when wires are disconnected and reconntected several times, and even more without insulated ferrules (though such ferrules are not allowed for some screwless connection types, also typically cross section restrictions apply when using crimped ferrules).
It would habe been interesting to know which cross section was used and if with or without ferrules and, if applicable, exactly which type of ferrules and how they were crimped. Poorly crimped ferrules are very common and also since a couple of years sub-par cheap non-standard Chinese junk ferrules can also be found.
Even if the cross section is known, the reliability of the connection can also depend on the quality of the copper. Depending on the manufacturer, conductors of the same construction (strand diameter and number of strands) can feature strands which will break more or less easily, especially if there are vibrations. Also thermoplastic and elastomer materials can become more or less brittle. Overall often we just get what we pay for… A RADOX 155 (or even only 125), TITANEX, or some cheap insulation? Let’s see the degradation in 10, 15 or 20 years.
If I had enough money to buy a container ship (sadly I do not have 150 to 190 million US$ 
) I would for sure rely on a much more serious electrical design. Some details are close to kindergaten level electrical engineering.
Investing 1 or 2 % more would allow a much more reliable electrical design and a small part of it could be recovered as energy savings.
In comparison, the electrical design of some modern VLCC’s as well as most DP-3 vessels and very large cruise ships is more reasonable.
Sorry folks, I’m not a regular here, and I had originally posted this on the other thread regarding the 6/24 NTSB update. I see that thread is pretty much stagnant and this is the main thread on this topic.
I have tried to read all the posts on this thread, although it was quite painful thanks to the Sercos guy… If this was brought up earlier I apologize…
Original Post:
I guess a question I have is why the “normal mode of operation” according to the report, is to have the LV busses tied, and feeding the LV bus with only one 6.6k/440v xfrmr. In the power industry, the tie is not normally closed, and sits there waiting for a loss of one side of the bus feed, then quickly closes to keep the bus hot. With them running with only one xfrmr feeding both LV busses tied, that seems very much non-standard. Its ok, but I would only expect that if the other 6.6 to 440 xfrmr was out of service for maintenance, or was damaged. But for the report to call that standard operating mode feels odd.
Also, FWIW, that has to be the most ridiculous naming convention I have ever seen. HVR, and LVR you would think would be called HVT and LVT (T for tie). And HR1, HR2, LR1, LR2 would be would called HV1, HV2, LV1, LV2 (V for voltage)…
And yes, I agree with prior comments, I cant stand those silly push-in terminal blocks. Give me a screw terminal block every time, and yes every good electrician knows after you make the connection you pull on it to confirm its secure.
I have replied in the other topic.
The power distribution architecture is completely different in the industry. To avoid single point of failures, transformers can be run in parallel with segmented double ring busbars, etc.
Extremely important are ride-through capabilities, while everything critical is on UPS, many process equipment and machines can tolerate a very short interruption required to reconfigure a power distribution system automatically.
It would be very interesting to know exactly how long a ME can ride through short blackouts, especially as above some speed there is a windmilling effect, which also means that emergency lubrication must be provided as the ME will not stop immediately and braking air can only be supplied below some speed (maybe around 20 RPM).
The whole Power Management is quite simple and also ME controls, steering gear controls and thruster controls should be designed in order to optimize overload emergency operation based on mesurements (recent load history) and allowing several emergency overload levels to be selected.
Based on the PR, the conclusion is quite simple: The duration of the 1st blackout should have been reduced to a few seconds by automation (closing HR2 and LR2 automatically).
For the 2nd blackout it is not sure if automation would have made a difference as DG2 (on stand-by) started automatically as the HV BUS lost power, supplied automatically the HV BUS as DGR2 closed automatically and the crew manually brought online TR2 and all this within about 31 seconds.
Obviously HR2 and LR2 should have been closed automatically but we do not know how many seconds, if any, would have been gained and it would probably not have made a difference anyway.
Dali has shifted from VIG terminal to NIT Pier-3 in Norfolk, VA. Crane barges are alongside.
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Says it all …
Wonder if there is any damage below the waterline that would need a DD … if so, wonder what they can do. Available options are next to nothing.
Up to about 10 meters (33 ft.) from the upper edge of the bow thruster tunnel there are no containers.
Considering the number and weight of containers, the structure is designed for quite high loads, that also explains the sort of limited damages caused by the bridge.
Overall I do not even expect the bow thruster to have been damaged and the first 20 meters (88 ft.) are not critical anyway, there was mostly some damaged deck machinery but the volume below is designed to end flooded in case of collision.
I am wondering if the main repair work will be done in Korea, I suppose some repair parts have already been manufactured.
As I understand it, the DALI turned starboard in the dredged channel out of Baltimore, went aground and contacted a bridge pillar there. Then the whole bridge collapsed. Why the DALI turned starboard is still not clear. The DALI Voyage Data Recorder incl. voice recorder was switched off, etc. I think it was criminal sabotage but cannot understand why. The DALI ship owner has limited it’s liability as per law (USD 44 million) and it’s P&I club has provided a bond for that amount.
I heard the lizard overlords plugged a USB right into the transformer.
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Out of context. I am not talking about damage below the forecastle deck with the Key bridge landing on it.
We do not know the structural details of the Key bridge pillar below the waterline. Possible the side shell contacted the concrete pillar before the bulwark contacted the bridge support structure above the water line.
On the video we see what looks like a bounce to the left seconds before the contact above the waterline and the bridge falling. Possible of course there is aggregate, small rocks and mud surrounding the pillar and side shell scraped this.
The Key bridge pillar below the waterline stopped at the sea floor. It is still there. The pillar above waterline was apparently broken due to the DALI thin plate forecast’le contact. I don’t think such ship structure can damage a solid concrete briidge pillar!
With more extensive damage she would not have been allowed to sail before more corresponding repair work would have been done before.
The VDR did not stop working (including recording bridge (wheelhouse) and wing audio) as it is supplied by an internal 12 V battery (details already discussed), but all external devices which were no longer powered stopped transmitting data, also external separately powered (non-UPS) sensors were no longer able to provide signals. Once power resumed there is a small delay before resuming operation which depends on the used equipment.
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Funnily USB is the major risk when it comes to viruses, especially also as nearly all mice and keyboards are connected to USB ports. There are even USB sabotage devices which damage USB ports physically, especially as USB is an awfully poor technical design.
Unless there is a network connection, USB ports are usually the most critical accesses since CD-ROM/DVD drives are no longer common.
That said, overall the highest risk is MS-Windows itself, it is way more probable to have issues with Windows updates than viruses if users are somewhat careful. Most viruses can be avoided but there is nothing which can be done against a Windows update messing up a computer as soon as there is an Internet access.
If MS server DNS’s are hacked, hundreds of millions of PC’s could be affected in a very short time. The largest single point of failure of our whole society.
COVID-19 would be peanuts in comparison.
Most critical systems are not controlled by some MS-Windows itself but the HMI displays (including ECDIS, RADAR displays, ME MOP’s, etc.) are nearly all running under some MS-Windows.
If Windows servers crash due to a common cause, most process controls are also lost, leaving the factory-level automation running but without means to manage it from the control rooms.
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IMHO it was just a freak accident, nothing more. Some root causes and maybe some handling error. Sure is that the PMS failed and the electrotechnical design itself was flawed, there are lots of weaknesses and some are common to most if not all modern large container ships.
When having a very close look at some electrotechnical details one would be very surprised how awfully outdated some relatively recent designs are.
For designs with discrete signals (not data communication) it is surprisingly easy to take control of the rudder IF someone has access to the wiring. The same applies to telegraphs (not bus-based ones).
Other way around. Question is did the ship sustain damage below the waterline. No doubt the support pillar is intact and by the way it extends well below the sea/river bed.
And jet fuel can’t melt steel either, right?
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We’re debating engineering with Heiwa, a guy whose website insists that no atom bomb was ever dropped on Hiroshima.
(Yes, you read that correctly).
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Are there images showing the underwater damages?
Yes! Burning jet fuel cannot melt steel or aluminum! l Basix!