NTSB Prelim Dali Baltimore Bridge Collision
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- Опубликовано: 5 июн 2024
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TR=Transformer. NOT Transformer Rectifier
This is especially significant. The low voltage bus is just stepped down from the HV bus. Except for the emergency LV Generator, there is no independent source of LV power.
I would also add, that these circuits are protected by both Circuit Breaks and Relays (although also fuses). CB are less complex, less prone to failure; relays are more suseptible to failure. Relays are also the mechanism that can bring another generator on the online via automation if one system fails.
What also has to be considered is the syncronization of the generators as well as the load sharing of the system. I discuss this in a RUclips vid I did, but will not refer to unless JB approved that.
I suspect, the investogators will be looking closely at the relays... it is going to take months, if we are lucky to duplicate the event sequence.
John
the electrical configuration doesn't look like it was configured in a particularly robust configuration, as i would expect for a ship entering or exiting port. of course i was in the navy and we took ship safety seriously.
@@Geek-A-Hertz8707 I trained at USMMA and was in the CG as a marine casulaty investigator and pilot.
This system is robust, but it was not built designed for instantaneous recovery in the vent of a power failure. Also keep in mind, the in the marchant marine, you have a crew of 22-25 people. The special sea detail in the Navy would have this many people on the bridge alone.
Also, the propulsion navy systems are not what you are seeing here. This is a slow speed diesel, that is about 40-50 feet in height and the pistons are about 4 feet in diameter each. The dimensions are just mind boggeling.
At the end of the day, the type of contingency that occured here was not antcipated into the design of the system. It is likely there will be changes, its only that the changes happen so slowly, that by the time they are implemented, the next latent design failure will have already been sent out to sea.
John
@@JBHRN I understand what you are saying, but my opinion is that from a ship safety standpoint having a single point failure, that allows the ship to lose steering while in a channel should be considered unacceptable. As a minimum you would want to have the steering gear powered from multiple and separate power sources when in the channel. such that if one power source goes down, the other can pick up the load without interruption. I understand that isn't the way things are designed right now, but I think this accident shows that the electrical systems on commercial ships need to be updated.
Juan - On the ships I worked on the emergency generator never supplied power to the ship's service (440 Volt low voltage bus). I believe the NTSB drawing doesn't show that there are breakers between the emergency bus and the ship's service bus as well as one between the emergency generator and the emergency bus. Key electrical loads (like one of the steering pumps, emergency lighting, etc.) are connected to the emergency service bus. Normally this bus is powered from the ship's service bus. When the ship's service bus fails, the emergency generator is started and when stabilized power to the emergency bus is transferred from the ship's service bus to the emergency bus. If the emergency generator were directly connected to the ship's service bus via the emergency bus it would be quickly overloaded and trip off line.
@jimprice1959, In theory, and this is a bit of conjecture, a transformer will generally work in either direction. For instance I had a client with a 480V machine in a 120/208 shop. We just wired the secondary side to the 120/208 and the output on the primary was outputting 277/480. Now I don't know if it would be possible to tie all the busses together, you might be able to get some power to cooling and oil pumps. is that an option in these types of systems?
The ships wiring diagrams were significantly (over) simplified for this preliminary report. I was concerned about having the emergency generator connected directly to low voltage buss, especially if HV buss may be connected.
The other major omission from the wiring diagram is the container refrigeration load. To me, the need to power shipping containers presents a significant risk to the ships power system. For critical maneuvering there needs to be isolation from the safety/propulsion etc. so that a cargo problem do not take out propulsion.
Sure you can up voltage through a normal transformer but the amperage available would be minuscule. Also these are transformer rectifiers so there is a good chance power would not backflow. As a lot have stated here, this is probably more of a Block diagram than a true schematic of the system.
@@markchamberlin7990 The reefer containers are fed from the 6,600 volt bus. There are numerous 440v 3 phase transformers located near to where the containers are stored, and then extension cords are run from the lashing bridges up to the containers, and each individual reefer box has it's own breaker. Because you don't want a short in a refrigeration compressor in one companies reefer box to trip a breaker and cause cargo damage to someone else's cargo. They do not run 440v "home runs" from down in the engine room to all the reefer boxes, that would cost too much in copper wire, and too much voltage drop, and like you said, you cannot have a big fault on the reefer containers to risk taking out critical engine room equipment like lube oil pumps, purifiers, fire pumps, bilge pumps, fresh water pumps, sewage treatment plant etc.
By placing individual small 6600v-440v transformers close to where the reefer loads are, this is cheaper and more reliable than running miles of heavy gauge copper wire to all the reefer boxes receptacles on the ship, because you can transmit a lot of kilowatts on a relatively small diameter 6600 volt wire.
You have experience and know exactly how a ships electrical system really operates.we know the NTSB is not very accurate at times.But don't try to say that to Mr Juan!! You know he will only focus strictly by what the NTSB report says. Just as a race horse with blinders that can only look straight foward but doesn't see everything else surrounding him.but thanks for your input.very well explained and it makes common sense. Something not everyone has.😂
As a retired Electrician, I totally agree with your analysis and thinking about re-setting a main feeder breaker that has just tripped out. Especially when both the HV (high voltage) and LV (low voltage) breaker on either side of a major step down transformer BOTH tripped. For me, and my work experience, I would immediately suspect a major fault within that major transformer and would NEVER reset the HV breaker and re-energize that transformer before it was tested for faults.
All of that said, it certainly seems like they were already so close to the bridge pier that even if they had initially closed HR2 and LR2 instead of re-closing HR1 and LR1, they would not have had time to re-start the engine and get things under control fast enough to avoid contacting the bridge pier.
Depends if the breaker was tripped or just off. Agreed if it was in a tripped state. If it was just “off” then there could have been an issue with the power management system. It would have been absolute chaos in those few moments.
That seems like a very poorly thought out electrical system. The fact that it has multiple redundancies for generating but multiple single point failures that can kill the engine, rudder, HV *AND* LV busses is just crazy. You would think there would at least be an auto-trip override that can be selected during critical phases to ensure the engine and rudder will keep running regardless.
It seems like the system was primarily designed so that it protected itself as opposed to protecting outside objects that might be in the path of the ship.
The system was designed to protect the main engine from damage and if they were on the open ocean diagnosing and fixing a fault would not be a time constrained problem. Time was not on their side in this case.
@@BlueSpruce2yeah, they clearly need to have a different mode of operation in tight quarters. It seems like just having both sides running redundantly would help a great deal, at the cost of running more generators. Doesn't seem like a big deal to do that for an hour or two.
@@BlueSpruce2 i would expect that running a ship on its own of this size in canals would have some regulatory demands regarding the redundancies especially in steering...
@@RichFreeman Running extra generators during a critical maneuver would seem to make a tremendous amount of sense. I also wonder about the logic of putting the engine support equipment on two different busses. All you seem to do is double the risk of an engine trip.
We need a collab between Juan and Sal over at "Whats Going On With Shipping"
Actually, with Chief MAKOi who is a ship's engineer.
sal put out a rushed, barely comprehensible post earlier today. Juan does a better job here in less time. sal knows very little about electrical systems.
@@gregknipe8772
The latest video on sal's channel is 32 minutes long, is that the one you're referring to?
@@gregknipe8772 That's the great thing about collabs. Combined knowledge. Get Sal with someone who can fill in the blanks.
Why Juan has no say why would anyone listen to him he not a investigator he's a RUclipsr that's it
Thanx Juan , I’m also a hundred Ton near coastal Master ! All the vessels I move are much smaller and less complexed. I never accept a vessel
Until I have scrutinized its sea worthiness ! I’m amazed that such a big vessel doesn’t have two separate power plants totally independent of each other ! The whole system you just explained in my opinion is a total can of worms !
To many variables for things to go wrong ! ( Give me simple and dependable)
They kind of do, if you look at the single line diagram, it is possible to split up both busses and start up all 4 generators, and have two completely independant systems if it was needed, with two separate transformers, if you open both the high and low voltage bus tie breakers. You could have the pair 3,4 powering TR2, and the DG1+2 pair powering TR1.
@@brnmcc01 Thanx for the response I’m sure if I was a lot younger I would accept this kind of engineering! But it just seems to me the-amount of money involved in moving this much cargo an accident should not happen ! And here’s my thoughts on this accident! ( True Safety is No Accident !)
If by power plant you mean main engine then it's no more amazing than that a Cessna Caravan does not have four engines.
@@RicktheRecorder Hi Rick thanx for your input ! In my experience with over 25000 hrs
Of flying time and over 2000 days at sea
I’ve always had two means of propulsion
Except when I was a single engine pilot
Building time for the Airlines . When I was a single engine aircraft pilot I always kept a suitable landing area in sight in case the engine failed ! As a Master of
Sailing vessels , up and down the west coast I had sails and an auxiliary power plant !
I always had a way out when the shit hit the fan ( 95 percent of the time ) two means of propulsion was my philosophy!
Engines do fail although there pretty reliable most of the time ! It just seems to me after this latest collision with the bridge, that when your moving that much cargo that you could afford to have two means of propulsion on your vessel ! I’m sure we could debate this topic but during my time I’ve had several engine failures all of which were on multi engine
Vessels . No accidents injuries or violations just routine flying and passages ! Electrical failures , gears that
Wouldn’t come normally, pressurization problems , ext. In my opinion ,that big of a vessel and that much cargo needs two completely independent power plants !
Sincerely Captain Mark H Wirth
@@markhwirth7718 I am sure it would be great to have two main engines, but the fact of the matter is that the vast majority of the world's merchant fleets have a single engine. There is no general requirement for more than one.
JB... you are spot on as usual. What has been overlooked is just how complex the ship board systems are & the massive amount of electrical power involved. As you depict here, there are redundancies built in the system, however, you are NO recovering the plant back on line in a short period of time. The sequence of events point to single point failures in both the ship & key bridge designs. I have a video covering this, but will refrain from sharing without your permission Juan. John Hall, KP 95 (Marine Casualty Investigator USCG & CG Helo Pilot)
As someone not familiar with Large Marine Engines is there a specific reason why the main propulsion diesels do not have the ability to power their own cooling and oil pumps once they are started? It would seem like a very basic redundancy whereby you could isolate the main engines from loss of generator power.
@@andrewtaylor940 It's a lot like a modern automobile gasoline engine. The engine in your car also requires a lot of electrical systems, if there's a total power loss, the fuel injectors will not work, as well as the ignition coils, and the ECM/powertrain control module. All it takes is a massive short at or in the alternator, then the main battery fuse blows, and then you're dead in the water. You could try a jump start but nothing will happen since the main battery fuse is blown, and the battery isn't even dead, it would still have a charge because a momentary short isn't going to do much to it.
If the low pressure electric fuel pump in a car's fuel tank loses power, there won't be enough fuel pressure to run fuel injectors and the engine will stop.
@@andrewtaylor940 That is a good question, the answer is interesting too. So, there are shaft driven auxillary generators that are turned by the main engine when they are underway at sea. This is more efficent. It is effectively a PTO generator.
However, when maneuvering at low speeds in port, you are completely dependent on the Main and AUx Generators. The lube oil, fuel oil and pneumatic control of the engines are vert power "hungery.' Keep in mind, these engines are massive. 3-4 stories in height and with cylinders so large a grown adult can fit inside one. The support systems for the engine, are drawing thousands of watts of power.
Lastly, keep in mind, the faults of the system were in power distribution & balancing system. Again, we are talking 5-12 mega watts of power, the load sharing, generator syncronizing systems are quite complex. Think of this in the context of powering a small city, not a even like an 18 wheeler or other large diesel engine.
Investigators I suspect will find the root cause was in the power distrubution system, however; I suspect they are going to find some elements of human in error in the steps taken as a response to the power loss. I suspect the underlying problem was not corrected in their haste to get the plant back on line & that led to the second power failure.
This is a classic case of single point failure for both the Dali and the Key Bridge.
John
I keep seeing stuff said about the bridge having "single point failure" design. If you knock 1 out of the 2 piers out from under it, it really doesn't matter how much redundancy is built into it, does it? It's going to fall. They can't hover. lol
TR1 and TR2 on schematic looks like a transformers without rectifiers.
Yes. The ship’s service electrical system is AC, so no rectifiers.
@@michaelimbesi2314 Yes, I agree. I'm not familiar with this system but the simplified schematic and legend refer to TR1 and TR2 as transformers not transformer rectifiers and I assume that they would be three phase stepping the 6.6KV down to 440 volt 3 phase and agree with other post that it would not be likely that the 440 volt bus would have enough power to power up the 6.6KV bus
yeh - they would just standard transformers like you would have in a grid system.
Little slip from aviation terminology, where we use TR to mean Transformer-Rectifier instead of just Transformer like the rest of the electrical world.
I noticed that as well and although this is a bit inside baseball the fact that they are AC systems can present some complications due to the need for freq syncing on the gen sets. Parallel generators will make there RPM's sync form magnetic coupling but there can be a whole lot a flow while that's happening
3:20 Slight detail: "TR" means transformer" as is clearly shown on the schematics. A rectifier is only needed if you wanted to make direct current. Not a lower voltage.
Correct, the rectifiers are later on the LV bus, they are only used to charge the batteries on board like the batteries for the emergency generator set, as well as battery powered backup emergency lighting etc.
As an electrician, I can't recall ever using "TR" as an abbreviation for a transformer.
We always used XFMR. Maybe it's a maritime thing?
Highly recommend looking at Chief Makoi’s video as well. He has experience in training and being trained on simulators of similar accidents (yes, there are ship simulators, just like aircraft).
I'm looking forward to Phillip's analysis of this report. I think he was right the crew never had a chance or time to restart the main engines.
The seductively intoxicating fragrance from the bow of M/V Dali could be the result of damage to the 7000 kg’s of perfumery products on board.
I was an engineer in electrical power plants for 40 years. Double ended switchgear would swap automatically between feeds. Strange they don't do this in marine applications.
Watching some other channels, it seems most ships do have that automated. If so, why was it in manual mode?
In regard to the Master-Pilot exchange, no there is no review of something equivalent to an A/C's tech log. All faults would be recorded in the engineering log or other methods in the Engine room. The M-P Exchange is usually facilitated by a one page form provided to the ship with specifications and maneuvering characteristics of the ship. Part of this form is to report any active material mechanical impairments. However, a resolved problem like the previous day's blackout would not be consider relevant. The wording of the report on the exchange does not throw any red flags as inadequate. However, the final report will tell us more.
The least fail safe design possible...a clear case of why effective is more important than efficient
Fiat money and taxes pushes efficiency and cost reduction. Real money and nationalist economy push quality etc.
It had backups for the backups, and maximum redundancy available in the event of mishaps at sea. of course it is also designed to be repaired within a day or two and the ability to swap configurations within a few minutes with manual setups.
It looks like the transformer is at fault, reconnecting it caused more problems, so the choice to swap to the backup was correct, unfortunately it takes minutes to do all these things and the ship cannot sustain its main engine without both high and low voltage circuits in operation simultaneously, so ANY singular fault cuts engine power in moments to protect the engine, which is fine when you aren't sailing towards a bridge.
It sounds very difficult to prevent this incident, the only suggestion is to keep one Tug connected for steering purposes during precision navigation around civil infrastructure like bridges to prevent mysterious failures damaging property. if this had happened on the other side of the bridge it might have grounded, but it would already be resolved.
@@glenmcgillivray4707 This would be why piston-engine aircraft, for example, have two full electrical systems on each engine, each individually able to run the engine, but both used simultaneously so that if one fails, the engine keeps running. Perhaps a similar concept, where two fully redundant electrical systems, cross-linked with switches and breakers, not deliberately used so that one can be down for maintenance while the other is a single-point failure, but both required to be operational before setting sail, would be warranted. Such failures are obviously rare, and such measures would obviously be expensive... But would they be as expensive as dealing with this kind of disaster? Or would there be a cheaper way to accomplish the same ends?
I don't have the detailed actuarial and material knowledge to be able to say, but I think those are the pertinent questions to ask.
@@glenmcgillivray4707 How did power loss translate into steering off course (141°) ?
@@Skousen77 Power loss = inability to control the rudder, and the loss of main propulsion leads to no "augmented" steering by the flow of water over the rudder being accelerated by the prop (rudder is behind prop, so if the prop is turning, the rudder can direct the much more powerful flow of water from the prop).
As for why it didn't "just go straight", well it wasn't going straight to start with (there was already a discrepancy between GPS ground track heading and vessel pointing heading), and it would have only been pushed further off course by winds and currents from there.
Basically, if the vessel loses the main engine, it can't control where it's going, it's adrift. The water currents around that bridge are not so simple as to not affect the course of vessels transiting under that bridge.
Exciting to see what Juan has to say on anything.
In a world where 440V is "low" voltage . . .
In Canada everything 600V and below is considered Low Voltage, for example.
@@thebigmacd In the USA it's anything below 800 volts. 6600 volts is "medium voltage" :)
120-800 volts = low voltage. 800-12740 = medium voltage. 12470-33000 = distribution voltage. 69kv, 115kv, 230kv, 500, and 765 kilovolts is transmission voltage.
I remember a 440 box on the west side of pier l blowing up when getting waaaay too close blasting away with a fire hose washing the pier in my younger days at JSI, talk about a flash and pop, scared the s--t out of me, but I was young and wasnt about to leave one grain of sandblast sand on that pier, after that I was much more careful about what bounced off those big yellow boxes with the big red letters 440VOLTS. Years later after the shipyard and becoming a civil service surveyor on the utility side I learned a thing about real voltage on distribution system - truly a fascinating amount of power as mentioned by brnmcc01 - 31 years doing that - people have no idea what kind of things there are in the ground and under streets that make our lives possible, quite literally, a whole nother dimension - Im old and worn out physically now, but I wouldnt trade what I learned and did and those memories that I have for anything.
@@markbowles2382 Yup, one difference between 440v and 6600 volts is one puts you in the hospital, the other one in the morgue...
Juan, Thanks for the clear report. Some of the Marine Engineers seem to want to "dumb it down" with inappropriate analogies to one's home electrical system. As a matter of jargonic correction, this was not a collision. The NTSB calls it "contact". The Coast Guard will call it an "allision".
Thank you for simplifying this complicated (to me) electrical system!
Electrical current is not complicated at all. In wire its invisible, so people create myths and misconceptions instead spending 5 minutes to understand basics. Many books compare e. current to water flow in pipes, because its pretty similar - in that way (almost) everybody can understand.
Sounds like someone needs to rework the Kablammo side of the checklist.
Also of note - even if emergency power is allowing some rudder control, without the prop pushing water over the rudder, rudder operation is going to have very little effect. The ship is so big that it needs the water being pushed across the rudder to have directional control at low speed.
I'm surprised these things don't happen more often, honestly.
@tuxedotservo: Juan already explained that. Pay attention.
Shortly after this happened, one Chinese container ship lost power when leaving, New York, I believe, one more ship, on the same day had difficulties.
It is very common, it just isn't common where a bridge is struck by the ship with issues
@@gcflower99 you have a time stamp so I can go to it? I didn't hear it on first listen through.
@@carlthor91 I did hear about those yes - and while researching, I learned that even the new Sunshine Skyway has been struck in recent years.
Good thing all those systems protected that engine against the risks of overheating or insufficient lubrication.
On warships there is usually the option to put a system into battle override, where you can “shake it, bake it, and run it dry” sacrificing equipment for safety of the ship as a whole.
@@Rosatodi2006 That really seems it would be a useful feature to require in critical situations like this. If you're at sea then who cares, but within minutes of powering up and heading straight for a bridge does not seem like the time to worry about stressing or even breaking the engine.
Seems like a better design would have the low buss split during critical maneuvers, with both transformers active. Maybe even split the high buss as long as you're running two generators.
Then when underway, you can tie the busses back together and use one generator for the transit.
Juan, I don’t think those were manually-operated breakers. They’re handling multiple megawatts of power. I think that the NTSB meant that instead of the breaker automatically closing, the crew manually ordered it closed.
That's what I was thinking. I can't imagine that they physically, manually operate those Breakers.
So similar to a Electrical Generating Station, Juan you are spot on about your observation that you never attempt to reclose a tripped breaker without first ascertaining why it tripped in the first place.
It seems to me this implies the ship is not made for maneuvering and it needs tugs until well out to the free lanes.
Or too complex for the crew to handle?
There is nothing that these ships do quickly, and without even minimal propulsion they do not turn even with a full rudder
No. The engineering and potential points of failure are well understood. It comes down to how much cost and regulations are tolerated for very rare failure conditions.
Precisely the same as why Norfolk Southern was allowed with excessively long rolling stock.
Just like every other similarly sized ship, which since their inception have navigated channels as small or smaller without issue.
On thinking about the report a bit more, I suspect the cause will be a circuit breaker on a piece of defective equipment, or circuit, that failed to trip when the circuit overloaded. This caused the HR1 and LR1 breakers to trip and when these were reset it tripped the DG3 and DG4 breakers.
When a circuit 'pops' the system is telling something is not ok, like Juan explained. Puzzling Why crew turned that circuit back on, when another circuit, HV2 and LV2 is available. Must be more to that part of the story. Possibly more complexity to just switch over that we don't know at this time. Thanks Juan as always for expertly explaining all issues.
It sounds like something the crew might do in a panic.
@@WG55 panic plays a part, but poor procedure and system understanding is more to blame. If your primary system fails, you should immediately switch to any available backup because something is wrong with the primary. Reclosing those breakers that opened automatically shouldn't have even been a thought.
Also secondly, the emergency generator should be able to power the low voltage bus. If that diagram is accurate. (It may not be)
They are just transformers not transformer rectifiers. They change the AC voltage to a lower AC voltage. Your transformer rectifiers in your triple 7 change AC bus power to DC bus power.
Just trying to rectify your comments. 😂
"Step-down transformers" in the NTSB Report.
OUCH!!
I'm dumb. What's a Rectifier?
@@temekuguy3465 A rectifier converts AC to DC.
So both the 6600 V and 440 V busses are alternating current, probably 50Hz or 60Hz.
Juan, this was a really interesting video. Thank you for taking the time to put this video together.
Thank you for your excellent explanation, Juan... you are indeed a national treasure.
Thanks for the update, Juan.
Nice job explaining and simplifying for us, Juan! Good luck with the Fly-In this weekend!
Juan, I believe the T1 and TR2 are merely 6KV to 480 3 Phase AC transformers, not rectifiers. At this point in the power schema, it is all 3 phase AC. Any DC buses come off the 480V bus thru any appropriate rectifiers. AC motors are much easier to control and maintain.
Correct. There are no DC busses on a ship.
6.6Kv HV and 440V LV.
My dad is a pilot I enjoy your videos and break downs of everything you do
Juan, You did an excellent job explaining the Preliminary report. I was however disappointed in the NTSB preliminary report. There was no mention of crew qualification and experience level (hrs aboard). There were also no explanation as to why BOTH transformer breakers open in one loss of power, nor did they discover / explain why the 3 and 4 generators opened in the second power loss. In my mind the report leaves more questions than answered with regard to the root cause of the problem.
That will all be in the Public Docket.
I'm glad your covering this
Great video, as always. IMHO, if the crew had switched to HR2/LR2 after the initial black-out instead of manually closing the HR1/LR1 pair that had just tripped, the only difference would have been that the second black-out could have been avoided. However, I very much doubt that there was enough time to restart the main engine and regain propulsion and avoid hitting the Key bridge pillars.
By far, the best coverage and explanation of this report I have seen. I've seen several. Thank you Juan.
Juan, I want to say thank you for all the great work and dedication that you put into the videos. I’ve been following since the Oroville dam series. Your videos are very informative and are explained in detail. I appreciate all you do with your channel, thank you.
Juan, your channel is a master class in ADM and by the end of even this one I learn so much more. Thank you
Thx Juan for diving into the Dali collision with the Francis Scott Key Bridge.
Thanks for the great explanation of the systems of the ship.
Sounds like a fuster cluck!
😂😂😂😂😂😂
I know it's nitpicking, but it's not "transformer/rectifier", it's just "transformer." There's no need to rectify the voltage (from AC to DC) because everything on the busses runs on AC alone. Makes no difference to the explanation but makes this retired electrical engineer cringe each time :)
Regarding the resetting of the breakers - I agree completely. On automotive forums, people mistakenly think that when a fuse or breaker pops, it's "bad". No, no, no - it's telling you that there's a problem downstream, and resetting it is not fixing or changing anything, so it's going to happen again, possibly damaging wiring, but I digress. Thank you for bringing it up!
@kurtbilinski1723 I was wondering about this... if they are just transformers might they reflect power on the LV bus (being suppled via the emergency generator) back up the the HV bus, thereby re-powering the oil pumps etc??
There is a breaker that opens when the emergency generator is providing power that isolates the low voltage bus from the high voltage bus. So it won't backfeed.
What’s really important about this report is how all these systems were affected and how there are no failsafes or redundancies pertaining to navigation, just to protection of equipment.
I wonder why the switchgear wasn't automated at all. Double ended gear has been around for well over a half a century.
@@paulmea3166 probably an accountant working on shareholder profits.
I have watched a couple of other shipping RUclips channels and none have described in detail the electrical setup as you have. Once again your videos are factual and thorough. Well done.
Thank you, Juan for your excellent report on a very complicated accident!
Once again, Juan, you bring a degree of clarity to an 'off-nominal situation' that we just don't find elsewhere. Thank you.
Great video Juan. We share a similar background with T-Craft early ownership, A&P, and many years of airline experience. I too was very interested when I read the initial NTSB report on this collision and found it striking to see the many similarities that the electrical system of this ship shared with a complex aircraft’s electrical systems. You did a nice job of explaining the systems. Thanks for another good video. Cheers, Rog
Wanted to thank you, I believe you promoted what’s going on in shipping channel and I have found it fascinating and I live no where near boats and maritime. Thanks for sharing as always.
The exchange between pilot is essentially a review of the maneuvering card of the vessel (details on maneuvering characteristics). The Master remains in command and the "harbor pilots" are there as advisory agents to the master. Deficiencies in the vessel status what is to be shared, is at the discretion of the master of the vessel.
And did he use proper discretion??
Maybe not..we'll know in a couple years...
Interesting comments throughout and I am glad the issue of the role of the pilot is raised. The master of the ship ( captain) is always in command. The chief engineer is trained and responsible for the ship’s power plant and auxiliary systems and would likely have declared that all systems were seaworthy to the master before leaving the dock.
Your explanation on the DALI incident has been the best I have heard Juan. Cheers.
Thanks for the breakdown. Take care
I don’t know why, but I love the deep dive into these kinds of incidents. Great job
Juan.
Juan, I can't thank you enough for this type of reports. You are absolutely stellar at explaining the facts so non experts in the field can understand them. Thank you!
I can picture Cheif Makoi shaking his head in agreement with your description. Thank you for posting all the interesting informative videos on your RUclips channel
Juan, it is stated in various sources that the Engine is an MAN B&W 9S90ME-C9.2 (for what that is worth).
That "design" looks like it is ready to fail by design, rather than work while enduring many issues.
If HV fails, the oil pumps stop and the engines stop. If LV fails, the water pumps stop and the engines stop.
What does it take to keep the engines running? Absolutely no swiss cheese, it seems!
I was thinking that. Maybe it's because the oil pump needs more power than the LV can supply, and the water pump is on LV to avoid the risk of having sea water near HV. I'm speculating, but it seems reasonable.
I wonder if, as the system can be split, it should be split in constrained waters like this.
And if possibly all generators should be running, producing power or be ready to do so at the drop of a hat.
Maybe there should be an emergency generator just for oil and water cooling that should be running in confined waters and if the engine senses a failure there, split them from the main busses and have the dedicated emergency generator take up the slack.
When you are in the middle of the ocean if you loose power you have time to fix it. Some hips have drifted for days while the crews work to fix a problem. In aircraft you don't have time to fix things so aircraft systems are designed to run as long a posslbe.
@@stevenf1678 There's also very few repairs, if any, that can be done in flight even if there is time. Ships don't have this problem.
The wheels in these busses definitely didn’t go round and round…
Best reply on this thread!
Very insightful Juan.
Thank you.
Small recommendation, Transformers are just called transformers, no need to add rectifier to the name when it’s just ac.
Is it possible that the low voltage side is Dc. If it is that would be the reason for the rectifier. Just wondered about that. I know about electricity but I don’t know about ships.
@@cew995 I'm pretty sure every component in that diagram is ac device
I did read an article on modern marine electrical systems that did have one or more DC busses. Each piece of equipment would then produce its requisite frequency. A good example of this would be a motor with a VFD, i.e., variable frequency drive.
The third rail in the NYC subway system is a DC bus. The modern cars have VFD’s and inverters as needed.
@@cew995 It's not, it's 440v AC 3 phase. He just thought it was rectifier from the R the NTSB added to the 1 line diagram meaning short for TRansformer. There are rectifiers on board, but those are contained in the battery charger units throughout the ship to charge batteries for battery powered emergency lighting, the battery backup for the VDR, emergency diesel generator starter batteries etc.
@@cew995 Some ships have DC distribution systems. World war II fighters did have 120V DC systems.
This is so informative! Great job, fantastic reporting!🌻🌼🐝 Keep it up 🙌
The second to last paragraph of the NTSB report should also include the review of requirements and standards for a vessel to be approved as seaworthy and the training and certification of the crews operating these ships. A needed review process such as this is difficult with vessels being registered in countries with lax standards.
Very educational Juan. I will be looking forward to further info when it comes out. There's a lot experienced engineers in the comments to learn from too. Thanks again for all the effort you've put into this and your great channel...See ya here!
Brilliantly explained, as always!
Great report Juan!
I got a tour of a USN vessel that showcased all the major ship systems. I was surprised (but probably shouldn't have been) at all the backup systems available. Nothing had more backups than the rudder. The last rudder backup was a completely manual system that required four or so really strong guys to manually operate some kind of winch/ratchet system that could move the rudder very slowly.
I did the math on this, and foound that the vessel moving at 6. 5 knots, with 100,000 DWT has the kinetic energy of a Tomahawk missle (1/2 Metric Ton of TNT).
I would also add, that the rake on the bow may have overwhelmed the effect of dolphins on the efficacy of bridge protections gained. I will also talk Repete and Fig about plugging the scholarship program on "So There I was..." Stay well Juan... Sticks
How much force/energy does it take to change off the correct course (141°) ?
At what angle can a rudder without propeller wash make that force ???
@@Skousen77 So we need to consider that this is a "Neo-Panamax" vessel, about 950 feet in length and a beam (width) of 150 feet. Without the prop, pushing water over the rudder that rudder is all but useless.
Think of the rudder as an airplane wing, but vertically oriented in the water. With the dessel "dead in the water" as the vessel travels through the water it displaces the water away from the rudder... so there is not any angle you can put the rudder at, that is going to have any effect on the course over gound of the vessel. (Heading and Course over gound are two different things)... in this case, transiting the channel, the thing that is more important is Course over gound and 141 is desired.
Now we need to add one additional factor, at the point of the power failure, all control over the rudder was lost. It was going to take 45 seconds for the emergency generator to kick in and that that point, you will limited rudder control as opposed to the normal system when the vessel is underway. Per the IMO, (int'l Maritime Organziation) emergency steering should provide control of the rudder to the extant that the rudder can be moved from 15 degrees starboard to 15 degrees port in no more then 60 seconds. That is significantly less then what normal steering ranges, are which are 40-45 degree port & starboard.
As Juan's channel focuses on aviation safety issues, realize that when a vessel loses power, it is not going to come screaming out of the water like an airplane out of the sky that has lost its engine. The emergency systems were also not imtended to mitigate the critical 90 seconds after the power failure at the same time the vessel was planning to negotiate the channel under the Key Bridge.
THIS WAS A FAILURE OF IMAGINATION. The designers of the bridge did not antcipate 60 years ago the massive size of ships navgating our aging infrastructure around US ports. It was generally assumed a power failures such as this would happen at sea where you have time to work the problem and not at a critical point of navigation.
This is a massive sentinal event that is on par with the Exxon Vadez, the Evergiven, the Andrea Doria - Stockholm collision or tje Titantic. There will be regulatory changes to follow this event.
I also think, the human facotrs of this event are going to stem around how the ships crew responded to the power failure... this will also be something that is going to change. I hope, the investigators look to aviation & generate EPs like that we having in aviation for similar maritime emergencies.
Again, just my 0.02 on this
John
The ship never made contact with the dolphins.
@@GregoryVeizades That is an interesting point. So the profile of the ship you see what is referrred to as the "bow rake". This is where the main deck extends out well beyond where the hull is on the water line.
Aircraft Carriers have huge bow rakes. As container ship size increases, so does the bow rake to accomodate massive number of containers on the ship. This is something that is seen with the
"Panamax" class of vessels. (Dali is a panamax vessel)
As such, the dolphins constructed around the piers of the bridges that span navigable waterways need to increase to protect the pier should that bow rake penetrate the protect area under the bridge. This can be done to a limit, as it will impact the width of the navigable channel.
John
Oversimplification of the electrical system leaves too much room for people to speculate on how the system should work and its reliability.
This incident gives another perspective for the watchword "Captain on the Bridge"
Close to becoming Bridge on the Captain
Have a great Fly-in!
Thanks Blanco.
Thank you for a great explanation of a complicated system and emergency. I enjoy your channel,former Saftey Petty Officer VA-215 U.S.N.
I literally just heard you on the radios at KGOO.
Very cool!
A lot of electronics to have to depend on when a bridge is looming directly in front of the vessel. There has been a couple of barges impacting bridges as well. I wonder if these incidents will involve strengthening bridge support bumpers.
Nice work Juan…
I don’t think the transformers contained rectifiers. It doesn’t say rectifier in the report.
Thanks Jaun. great info
Why did this ship have multiple single point failures that can cripple the ship?
Many do. When something goes wrong, they usually aren't going to hit something.... And I haven't heard of any falling from the sky from a failure. Much like cars, there is no need to have backup on top of backups for other backups.
If the electrical systems was configured differently there would have been better redundancy.
If DG1 or DG2 and DG3 or DG4 were operating. And if HVR and LVR were open. And if HR1, LR1, HR2, and LR2 were closed. There would have been much greater redundancy. And any failure would have only caused a loss of half the high voltage buss and half the low voltage buss.
I have no idea what the actual design intent was. I don't know if the configuration I stated has issues that I am not aware of. But it does seem to be a better configuration.
If this configuration was available the question is why wasn't it being used. Was it a sequence of operation (SOO) issue, a standard operating procedure (SOP) issue, an automation design/function issue or a training issue. We will need to wait for the final report to find out.
Excellent review. Just technical enough. And, thanks for the heads up on the open house at Nevada County AP. See you there.
I believe that the Cooling system is on the HV side. It takes a huge amount of water flow for that. The fuel pumps are not nearly the volume of coolant nor would I think the lube pumps. All those have to run in order for the Main Engine to run but you can split into parallel systems where either pump (or 3s) could keep the main engine running.
Main point being it requires both the HV and LV busses to be energized along with adequate air in the compressed air system in order for the main engine to be restarted. I believe they normally have enough compressed air for multiple engines starts/restarts before requiring a system recharge.
I appreciate the no-BS approach to these reports, Juan. The concise way you go through details is way better than the Death-by-Powerpoint I used to enjoy in the RCAF. Spent many hours standing at the back of the room to stay awake...
@OfficialBlancoliriolo yeah right scammer
Once again the immutable rule of human / technology interface strikes.
“ If there is even the most remote of possibilities to F something up, someone will eventually find it”.
As always JB. You're AMAZING! Even I understood that. Thanks for youe passion to teaching using "lay" language.
Thanks for your time and resources.
Take care and stay safe. 🖖🏼🤟🏼🙏🏼
I was hoping you’d cover this!!!!
Juan - this is the best technical analysis of the NTSB preliminary report I have seen. I think you hit the nail on the head regarding what the engine room crew should have done after the first breaker set tripped out, and that is to return to the last known good configuration of the breaker and busses i.e. use breakers HR2/LR2. That said, it is unlikely they would have been able to restart the propulsion engine to regain full directional control of the ship in time to avoid this disaster. Would be nice to know what fault conditions would cause both breakers to trip... Over current, over temp or short in transformer, faulty sensors etc.
Thanks Juan for an excellent summary.
The concept of system redundancy is something hardwired into our (aviation) culture and manifests itself in the rotation of critical systems to ensure that system integrity on a daily basis.
Here we have a single electrical channel operated for months at a time apparently unchecked, with the serviceable channel unused, presumably because SOP made no such requirement.
Some ship sized holes in the cheese.
Smells like linberger or stilton, too.
Thank you very much for this deep Dive into the Reasons for this Accident!🙂👍
Thank you Juan. Chief MAKOi gives a very good explanation too.
You have to understand how a system like that works. When the Emergency Generator starts, the LVR opens up (as would LR2 if it was closed) and just the small portion of the so called Low Voltage (440 volts) is then powered. While the diagram shows its equal it is not, only a few key system are on the E Generator side.
Open question: How did loosing power translate into stearing off course (141°) ???
Note:
1) Streaing is impaired if there is no propeller wash/flow to redirect
2) If not external forces acted upon the ship, direction and speed is maintained
Water moves and the ship is floating in water. If the engine is needed then the ship is fighting against the water.
Looks simple on paper, but probably looks complicated when your on the ship.
I suspect some piece of equipment on the 440 Volt ship's service LV bus overloaded the system and caused both the HR1 and LR1 breakers to trip. When these breakers were reset it caused the DG3 and DG4 breakers to trip.
Yeah I think Juan is out of his element here. The way the breakers were tripping doesn't sound to me like switching to the other transformer made any difference. The breaker downstream of the transformer tripped, and then the generators tripped. Whatever fault was likely intermittent and on the service bus itself. If the fault was on something exclusive to that side, the breaker downstream of the transformer wouldn't have tripped.
@@GigsVT It could also have been TR1 itself that was faulty. Remember that everything worked fine again after switching back to TR2.
I highly doubt it. You’re talking about a 4 megawatt short that somehow nobody noticed.
@@franklehmann3785 If TR1 was faulty it shouldn't have tripped LR1. I think it was downstream.
@@michaelimbesi2314 What about the existing loads? It all adds up.
Fair play to the pilots, sounds like they did everything right given the tiny space of time they had to act. Can't imagine what it was like to see that bridge pier looming up ahead!
Those sailor suits weren't white anymore.
They did it by the book but that isn't always the best course of action given specific conditions and circumstances.
The report creates more questions than it answers. What caused the breakers to trip?
I'd question the statement that the oil lubrication pumps for the main engine are connected to the H.V. bus. I don't know of any small or medium sized pumps that are operating off of 6,600 volts. Usually, the service pumps are running 440volt or 220volts, which means they should be connected to the L.V. bus.
You're right, the only pumps I've seen that run on that high of a voltage are the water circulating pumps at a nuclear power plant, 5500 horsepower each. There is no need for more than a few 100 and 250 horsepower pumps on even a large vessel as this. The only motor I know of on board that uses 6600 volts is the bow thruster, those are many megawatts and not possible to run on 440 volts, you'd need cables thicker than your arm, and would still probably melt, even if they made a motor that large to run on 440 volts.
Another great job Juan. I do have one thing to add to this. In the video you said the engine needs to be shut down completely and restart it in order to change direction from ahead to astern. That caught my ear, as I have never heard of this on a modern vessel, and I believe that is incorrect. The propeller shaft needs to be stopped by putting the throttle in the stop position, pause, then advanced to the other direction. Completely shutting down the engine to change prop direction is not only hazardous but counter productive in the situations it is needed.
I imagine the hectic scene in the engine as they were losing power and then what that must have felt like and sounded like from the engine room when the bridge came down on the ship.
I think any time that a “normal” restart will take 5 minutes or more, and you are 10 minutes or less away from a collision, you should have tug support. Do the engineers ever even train for this kind of problem?
Juan I am suspicious of how the electrical systems was configured.
If DG1 or DG2 and DG3 or DG4 were operating. And if HVR and LVR were open. And if HR1, LR1, HR2, and LR2 were closed. There would have been much greater redundancy. And any failure would have only caused a loss of half the high voltage buss and loss of half the low voltage buss.
I have no idea what the actual design intent was. I don't know if the configuration I stated has issues that I am not aware of. But it does seem to be a better configuration.
If this configuration was available the question is why wasn't it being used. Was it a sequence of operation (SOO) issue, a standard operating procedure (SOP) issue, an automation design/function issue or a training issue. We will need to wait for the final report to find out.
Speaking of the CB in aviation yes, you can reset the CB but it depends on which CB it is and if we are on the ground or in the air.
I work in engine manufacturing and I am quite surprised that water and oil pumps are driven by a different generator than the serviced engine itself. We mount all water and oil pumps directly to the free-end gear. I'm talking of 4S engines, but still... the principle is always to keep the engine running as much as possible even in case of system failure or underperformance.