4K HP BT
With 1400 reefers the electrical load would be around 6.1MW so I’m pretty sure that the set up would be as you described.
Hello
It is actually a 3k kW BT (3500HP). How many DGs on the board would depend on the reefer load. With 4 DGs of about 4000kW each, there should be no shortage of power.
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Hi Hogsnort
The typical reefer load is about 7-8kW for refrigerated boxes and about half that for frozen boxes. Not sure what they considered in their load analysis and what diversity/utilization factors they considered for sizing and the number of generators . I wouldn’t be surprised, if the spec called for sizing and number based on 1 DG down for maintenance. Rules call for 1 generator for full vessel service load and 1 spare. Most US built ships of yesteryear in my experience follow this IMO/USCG - 1 DG and 1 TG. Real pain in the butt. And most ‘rest of the world’ ships have 3. The reefer load on container ships gives the operators quite an edge in extra generation capacity/numbers.
On the Dali, we do not know the reefer load at departure … but fair assumption is nowhere near 1400. So they might have had 3 (or even 4) on the board without any worry of ‘spinning reserve’.
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Hi Spowiednick
Glad to see you remember your grade school physics formula for kinetic energy (1/2 x mass x velocity squared)! TNT equivalent is an interesting comparison
You mean “elementary” 6th grade physics. And if You call it “mine” i may feel offended but do not worry. I have declared already some place else I had a skin of a rhino 
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I am agreement that the reefer load was probably nowhere near the Dali’s capacity on sailing from Baltimore but with 4 generators the ship was sized to suit a full load. In my previous experience where we did load to our reefer capacity it took about 4 days with each box drawing the maximum power before the electrical load settled down. Probably due to some boxes being still in range but having been off power for a while before loading.
If there was just one electrician he would have been a very busy boy. Roughly 2% of boxes require some attention during a voyage. We sailed with 2 electricians.
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First confession, I have never worked on a box boat.
I do work with reefers. ect some are even boxes. Most if not all have their own power units. Some older units only had diesel. Now “we don’t carry” diesel only units and provide power for electrical units.
I can only comment on the units and systems. I have seen.
OSHA and Lock out procedures requirements are detailed. So regulations and requirement may be quite different. As to who does what when?
Our system is small so we can use a simple one man lockout procedure as opposed to a more complex multi person lockout.
I would imagine the procedure on a container vessel is much more complex.
There is a main breaker on main switchboard. It is both lockable and it is preferential.
Most of the time, Normal use While there are individual connections with individual breaker for each spot we can put a reefer. There is one main lockout breaker for all reefers on the main deck.
So we lockout our entire system while reefers are being loaded or unloaded.
I’m sure they do not do this on a large container ship or even a small one.
Ground faults ect are a common occurrence. We don’t have control over reefer maintenance.
When system is unlocked and breaker closed. The ECR can tell quite quickly if we have any faults. . Most run on diesel parked in open. Ships electrical system on board. So you can tell on standby by light and most have temp readings visible. There is a variety of switches ect on reefers.
If there is a problem its often in the connection. Water ect. We get a fault indicator. It will show on vessels power management system and individual breaker.
So not a problem to check and isolate if required. If not quickly resolved shipper gets an option.
Your reefer has a problem. You want it shipped as is or not.
Of course on a short costal run, We get crappy reefers and shippers who are willing to ship unconnected and not running.
If you want your reefer to get shipped across an ocean. I guess you give a shit if its in good operating condition. If your reefer is the problem it isn’t my problem.
Container ships might be different, Checking temps and reefers running daily or every watch whatever. is one thing, fixing faulty units is another.
Our system is our system, It pays the bills, we ship reefers, If there is a problem with our system its a big problem. We would get big cargoes claims if our system faults out and a shippers reefer goes off temp. Nobody is going to want warm ice cream. Or defrosted fish.
If our reefer system is not working it will pretty much shut us down. Not because CG Class ect. We would go broke on cargo claims. Everyone with money in the game is going to want it fixed PDQ.
Ship owner charterer ect, is not going to be happy if you get a ton of claims
Even though the refer system is important. Its on a preferential trip. The system will trip off before it overloads the ships system.
The chances of it tripping of without warning are very low.
The chances of the system not tripping off, are also very low.
The chance someone reset the system breaker after it tripped. possible but, why would an engineer would do this.
Certainly not while the ships on stand by.
I cant say the reefer system wasn’t a problem or part of the chain of events. I just don’t see why or how it would blackout a whole ship on standby in a critical part of the passage.
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I have never seen a reefer container with its own diesel engine and I never knew such a thing existed. you learn something every day. In the trade I was in, the charterer engages reefer engineers to pre-trip the boxes before loading and check them onboard before departure. We carried 3 different makes of compressors and spare parts that were supplied by, and the inventory maintained by, the charterer.
The electricians monitored the boxes and if they had to do any repairs they were charged out to the charterer. A written record of the electricians monitoring was done twice a day.
In my experience it takes a minute for an individual to check a box. This covers time spent climbing lashing bridges and opening Booby hatches and making the odd quick adjustment.
1400 boxes equals 1400 minutes - .hmm- you’ve got 20 minutes for a cup of Java son and it’s time to start again. Better hope the modems are working and you’re getting a printout.
I was being less than generous he’s got 40 minutes, 20 minutes shuteye and 20 minutes for coffee.
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Hello Uricanejack
I do not think anyone is saying a reefer trip caused a blackout. Based on the info available such as the vessel has 1400 reefer slots and 4 generators of approx 4 MW each, and while not confirmed the assumption is the generators are high voltage. Possibly 6.6 KV. So generators feed a HV bus that will feed all consumers on the vessel through a transformer as appropriate. Whole idea on the HV is save cost and the effort on laying/pulling thick cables of Low Voltage (LV) over long lengths. For the reefers these transformers will be located close to the bays/hatches equipped with the outlets. Assuming a 1000KVA is the about the correct size both electrically and physically it would be able to power about 115 reefers at about 7KW each. 7 x 115 = 805KW = 805 /0.8 = 1000 KVA (0.8 is the Power factor PF).
So for 1400 outlets we would need about 12 transformers. (1400 / 115 = approx 12 tranformers).
These 12 transformers (6600/440/3PH) will need to be fed from the HV switch board independently via a separate breaker. On the secondary side there would be a distribution board with breakers to feed a mutli-gang box of 440V reefer outlet. Perhaps 6-8. A single reefer tripping is not even a blip on the HV board. At the most it will trip the circuit breaker feeder to this multi-gang box on the above mentioned 440 distribution panel.
Coming back to the HV board, just as any switch board with large consumers, first time power up or power up after a blackout will need to be staged such that all breakers do not come at the same time causing issues with the prime mover with voltage drop/frequency drop/black smoke/shock loading the engine/etc. This is done on a sequential program such that the breakers are switched on in set intervals - about 20 seconds or so to enable the DG in this case to stabilize.
We do not know the cause of the first blackout. I think it may be the BT breaker or starter contactor when the crew go to secure this. And a very unfortunate consequence of this blackout is possible damage to the steering gear.
But on the second and third blackout, the conjecture is possibly on the sequential breaker closing program one of these reefer breakers is defective (not because of any reefer) and while closing there is some fault current generated or arc flash system activating that disconnects the incoming feeder(s) from the DG(s) and causing the dreaded blackout. The timing of the blackouts (2 and 3) after the lights on are also too close possibly indicating that it was 1 specific breaker.
Hope this helps. Keep those reefers coming … they are high margin cargo for the shipping companies!
Thanks.
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Hello all
I have a question on the funnel arrangement. In the NTSB B-roll - Aeriel imagery there are 2 reasonably large uptakes. One straight up without a mitered elbow on the stbd side and one (seems to be) slightly smaller a little to port from about centerline with the mitered elbow. The other uptakes for the DGs and boiler seem to be accounted for. In the actual video of the accident, the black smoke is from the port uptake. At first I thought the starboard one may be a HVAC exhaust for balancing engine room pressure. But then there are carbon deposits around the edge.
Any thoughts on what this could be? Could it be a scrubber installed on the vessel? And they have a by-pass arrangement in the engine room to direct the flue gas from one to the other? Maybe the larger stbd one is for sea service and the port one for maneuvering into port? No idea - just guessing.
Thoughts?
Hello all
An interesting update. There is a video on Youtube from ‘Maritime History’ titled Ship that destroyed the Francis Scott Key Bridge and one from ‘Shipping TV’ from 2019 arriving at Felixstowe. In both the videos the funnel arrangement is not the same as it is today. The port uptake has been added. Does look like a scrubber installation sometime after 2019. Separate exhaust added possibly not to interfere with the exhaust gas economizer coils. Has nothing to do with the accident - but just an interesting piece of info.
About 100 x more reefer’s than I can carry.
Most are drop trailers, Some Trucks, Some Semi, the odd container on a trailer.
So much much smaller and simple system.
Thanks.
The system I am familiar with are much smaller. RoRo Drop trailer Trucks ect.
My Question now would be more about procedure.
Routine practice, Once upon time we would have just hooked em up and turned them on as we loaded them. Until Auditor asked about our lockout procedure. So now we load them all hook them all up with system locked out. Switch the breaker and start them after loading.
Typically each reefer has to be individually started. This might be because drop trailers are different from containers.
This is all done as part of loading unloading so prior to departure or after arrival. On passage underway temp checks recorded operation checks ect.
I believe the breakers are sequential.
While we can run at sea on a single generator. (or SG, but lets not start that again)
Most of the time we run on two DG. (or SG). Even though not on SBE we are in confined busy area.
Even on two Gen there is a stand by gen.
Blackout recovery?
One Gen fails? Off shore on single gen, SBG starts 20 30 seconds later?
A problem? Yes. Not a big problem.
Some things need to be re started PDQ. some not so much.
Steering lost briefly.
ME recovered prior to auto shut down. Maybe Maybe not
If SBG doesn’t start right away. EM gen will start but ME will probably have gone into auto shut down.
Recovery a bit more complex.
You probably can run a ME on EMG only but would have to do a bit off reorganizing things.
Only designated EM systems will run.
Either way, Non essential systems are not going to be restarted until the critical systems such as Emergency systems, steering and ME. are restarted and running properly.
After everything checks out.
Non essential stuff would slowly be checked and restarted. (starting a faulty system might cause blackout to reoccur)
On Standby. Post departure, Reefer System is probably just one of the ships regular systems hopefully running normally.
Something cause a DG to fail.
All load will go to remaining DG and it will now be heavily loaded rather than a light load.
All non essential systems should trip off on preferential trips.
Giving the remaining DG the chance to stabilize and take the load.
The SBG should auto start. and Sinc with the Running DG.
So far So good recovery happening under normal circumstances.
Again preferential should have tripped. So only Essential and EM systems should be on board.
At this time, Engineering would be checking to see what is still running and what is not.
Restarting critical stuff first to keep the ship running.
Emergency systems, Steering, ME
BT would be tripped. Bridge may request. But Steering and ME are priority.
Bridge should be aware BT not likely after a blackout.
Very probably steering can be restarted locally or from bridge.
If the Ship is on Standby.
Why would non essential systems be reset or restarted? They wouldn’t be until the ship was clear of channel ect.
So why would would the reefer system be reset. or Restarted at this time.
Unless the system failed to trip?
For some unknown reason
Hello Uricanejack
Please take a look at my message 29 on theories of the first and the subsequent blackouts. On this vessel with ample generating capacity and while on stby, a DG tripping and (over) loading the other I think is remote. Do not think there was any load shed with the preferential system.
If our theory is reasonable to assume as high probability that a (an electrical) fault on the board caused the blackout, it is also possible only the incoming main breakers from the DGs tripped. Assuming there were 3 on the board all would have opened. But likely the engines continued to operate normally. In such a case, it would mean only to first close any of the 3 DG breakers and then sync up the 2nd and possibly 3rd. It took them just about a minute to restore power … so sounds plausible. If the DGs were 440 and the MSB is in the ECR closing the first breaker to get the lights on would be a matter of seconds. Since it is HV, getting into the HV switchboard room may have caused some delay.
Thanks.
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Thanks … guess these are for 40s. 20s should be a tad lower. BTW there are some 24s as well.
they probably wish it was tnt by now?