Baltimore Bridge collapse after ship collision 125

[Tomfh]

https://amp.9news.com.au/article/b73620ea-64ab-4253-8cb0-37102418fcab

 

[FacEngrPE]

NTSB releases investigation update on Dali ship that crashed into Baltimore Key Bridge, WUSA9

NTSB Issues Investigative Update for Baltimore Bridge Collapse 6/24/2024 Link

NTSB Investigative Update Release Date 24 June 2024 Link

 

[LionelHutz]

Using an undervoltage release on the circuit breaker seems odd.

 

[TugboatEng]

It's extremely common in ships as it's considered the most failsafe trip mechanism. Marine engine rooms don't typically have much DC backup. The alarm panel will have DC backup but not much else.

 

[Nukeman948]

Using an undervoltage release on the circuit breaker seems odd.

The purpose of a circuit breaker is to protect electrical equipment from potentially damaging conditions. They can be designed to trip on under voltage, over voltage, ground fault, arc fault, over-current, over-temperature or any other potentially damaging conditions.
Under voltage can damage many types of electrical equipment, especially motors and generators.
An under voltage condition on a ship with several generators could cause instability on the system and lead to cascading failures of generators and damage to motors and other equipment.

There has been no evidence presented that these breakers tripped because of an actual under voltage condition. The investigators are looking into a faulty terminal connector in the breakers control circuits.

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[Brian Malone]

Maybe it is obvious to many, but I have no experience with electrical systems that have an undervoltage release condition. Why would a system remove all power upon an undervoltage situation, thereby disabling all control? I tend to consider ship systems to be large process-type, industrial equipment, high horsepower, etc., not delicate micro-amp sensors, so what is being protected by shutting all systems?

 

[Brian Malone]

Thanks Nukeman! You answered my question while I was typing!

 

[Nukeman948]

The breakers protect electrical equipment, backup systems are needed to protect the ship and maintain control.

https://youtu.be/cy-3vR3t8U0?feature=shared

Motor overload protection is provided in most motor starters or in the motor itself and should trip for most under voltage conditions. Home refrigerators often use hermetically sealed refrigerant pumps where the motor is cooled by the refrigerant, but if there is an under voltage, the motor can stall and draw more current with no coolant flow, leading to failure.

Motors do not follow Ohms law. As many people know, if you run induction motors with reduced voltage they will slow down and draw more current, the opposite of what Ohms law predicts. But if you supply higher voltage it won't run much faster and it will also draw more current. Google "counter EMF" to learn why motors run best at their designed speed and voltage.

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[TugboatEng]

Brian Malone, it is very common to use UVR to interlock breakers and prevent them from being closed under certain conditions. UVR is also used to trip equipment during certain events such as deploying the fixed fire fighting system. The breakers feeding ventilation sub-panels will have UVR.

 

[Brian Malone]

Nukeman948 and TugboatEng - thanks for the details. They are very helpful for understanding the possible subtleties of the failure modes of the Dali collision.

 

[JohnRBaker]

The costs are now starting to become more apparent:

Lloyd’s of London faces £500m loss over Baltimore bridge collapse

Disaster expected to result in the biggest ever marine-related loss for the global insurance industry

https://www.thetimes.com/business-m...loss-over-baltimore-bridge-collapse-pkkk786n3

An excerpt from the above item:

The collapse of the Baltimore bridge that caused chaos at one of the busiest ports in the United States will lead to a £500 million loss for the Lloyd’s of London insurance market.

The disaster, which occurred in March when a cargo ship collided with the Francis Scott Key Bridge, is expected to result in the biggest marine-related loss for the global insurance industry on record.

Bruce Carnegie-Brown, the chairman of Lloyd’s, said that he expected the overall hit suffered by insurers worldwide from the incident would be more than $5 billion, but the loss to the London market would be a more modest £500 million, net of reinsurance.

Lloyd’s has been partially insulated from the fallout of the disaster because both the bridge and Baltimore’s port were insured domestically in the US. For Lloyd’s “it’s the ship, it’s the cargo that’s on the ship and then it’s the cargoes that were trapped in the harbour that couldn’t get out”, Carnegie-Brown said.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[LionelHutz]

UVR is not common in any kind of industrial environment. We have about 30 MV breakers on the shelves right now and none have UVR coils in them. We've only sold 1 in about 6-7 years. No customer wants them. It removes trip selectivity from the breaker control scheme since a control voltage transient can cause an uncontrolled opening of every breaker. You get full control over tripping of breakers by using protection relays and trip coils, hence why that's the dominant control scheme employed.

 

[JohnRBaker]

LionelHutz, it would appear that you've posted this item in the wrong thread.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Alistair_Heaton]

John it's relevant, it's to do with marine electrical systems which is involved with the accident.

 

[JohnRBaker]

Sorry if I didn't catch that, but then perhaps that should have been more clearly stated since there was no references to anything which linked it to the topic of the thread.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Sym P. le]

I applaud the post as is, even if i had to pause a moment to realise its import.

 

[Nukeman948]

UVR is not common in any kind of industrial environment. We have about 30 MV breakers on the shelves right now and none have UVR coils in them. ...You get full control over tripping of breakers by using protection relays and trip coils, hence why that's the dominant control scheme employed.

NTSB investigators (in coordination with vessel crew and parties to the investigation) noted an interruption in the control circuit for HR1’s undervoltage release.[1]Link

The NTSB often tries to dumb things down for the masses. It is very likely that this breaker had a trip coil (that they are calling an "undervoltage release") that was tripped by an external undervoltage sensor in coordination with other control logic to limit false tripping. It would not need to be a UVR coil that was an integral part of the breaker itself.

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[LionelHutz]

The breakers might have had UVR coils, but using them doesn't make a medium voltage control scheme simpler. You'd still want an uninterruptable supply to ensure a fault on the system doesn't "blip" the UVR supply and trip breakers you don't want tripped.

If anything, I would think that the propulsion and directional control systems on a ship this size need a more robust control scheme then what might be used in an industrial facility, since it's rather critical to keep those systems online unless there is an issue where they can't possibly be kept online.

 

[Alistair_Heaton]

https://www.npr.org/2024/09/13/g-s1-22490/electrical-cable-ship-baltimore-bridge-collapse

Came up in my news feed

 

[JohnRBaker]

It was just a matter of time: Another milestone in the history of the Baltimore bridge collapse:

Justice Department Sues Over Baltimore Bridge Collapse And Seeks $100M In Cleanup Costs

The U.S. Justice Department is suing the owner and manager of the cargo ship that caused the Baltimore bridge collapse.

https://www.huffpost.com/entry/bc-u...justice-department_n_66eae70be4b051614c509f80

An excerpt from the above item:

The owner and manager of the cargo ship that caused the Baltimore bridge collapse recklessly cut corners and ignored known electrical problems on the vessel, the Justice Department alleged Wednesday in a lawsuit seeking to recover more than $100 million that the government spent to clear the underwater debris and reopen the city’s port.

The lawsuit filed in Maryland provides the most detailed account yet of the cascading series of failures on the Dali that left the vessel’s pilots and crew completely helpless in the face of looming disaster.

The Justice Department alleges that mechanical and electrical systems on the massive container ship had been “jury-rigged” and improperly maintained, culminating in a horrific power outage moments before it crashed into a support column on the Francis Scott Key Bridge in March. Six construction workers were killed when the bridge crumbled into the water.

“This tragedy was entirely avoidable,” if not for the companies’ decision to place an “ill-prepared crew on an abjectly unseaworthy vessel,” says the lawsuit against Dali owner Grace Ocean Private Ltd. and manager Synergy Marine Group, both of Singapore.

“They did so to reap the benefit of conducting business in American ports. Yet they cut corners in ways that risked lives and infrastructure,” the complaint says.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Oops409]

Ok, if you are ready to learn what happened on Dali Ship, and are not willing to wait for the NTSB report to be released 5 years from now, here is a link to the 53 page law suit filed by the Dept of Justice Filed against Dali ship owners and operators.

This lays out a jerry-rigged ship where they bypassed automation controls and safety measures, and makeshift rigged stuff to to keep ship moving.....

Much more information than contained in NTSB reports to date.....although in legal document filing format..... Definitely the Justice Department had more capable people write this document, than NTSB had craft their reports....

Enjoy!

https://www.scribd.com/document/770...l-that-Destroyed-the-Francis-Scott-Key-Bridge

Edit: PDF uploaded Can't get pdf to show up on post? See later post for pdf, it finally took it....