And…….tamper evident preservation seals on the HV switchboard.
The breakers can also be opened and closed by signals coming from the vessel IAS - Integrated Automation System, which sometimes also have protection functions in its software. And it is possible that that trip order was not recorded in the event or alarm history of vessel’s IAS. Or the breaker was mechanically faulty and tripped by itself without a remote electrical signal.
I think that is what I was saying. Mechanical is possible but so is electrical in the opening and closing coil circuits. We don’t know the extent of their automation I/O’s but I would be very surprised if they were not able to open and close these from a screen, and if synchronizing was required that would be initiated, etc. but I would be equally surprised if each event in that process did not generate an IAS process message. If opening the primary side breaker to the SS Service transformer was initiated from IAS there would/should be a date/time stamped message(s). Breaker open command xx:xx:xxx, breaker open xx:xx:xxx
Again why not lay that out. Maybe Unified Command has them waiting until dockside to get into it? Do think the HV has been racked out yet? In test position, running through open and close commands?
Unfortunately not all events are recorded in the event history, it all depends how it was setup. Make no mistake, the first thing they looked at was alarm and event history of the vessel’s automation system. Probably nothing was found there related to the transformer trip, hence they call it “unexpected trip”.
I seem to remember we had a bomb linking the bus on one vessel.Seriously it was a very small explosive device that separated the bus in extreme circumstances and given it was 50 or so years ago technical details have faded with time. Here is my take. Ship departed with two SGM 1 &2 on line. On blacking out number 3 steering motor didn’t come on with the EG . The verbal commands and response happened on the bridge happened on the bridge but the rudder never moved. I imagine that the recording of audio on the bridge will have a number of people talking at once and it will be interesting to find out if the helmsman reports a lack of response of the rudder. I don’t know if things are the same now as they used to be with Indian crewed vessels but the helm in pilotage waters used to be done by one of the three quartermasters (Seacunnies) who were experienced seamen.
Generally Indian crews are of a very high standard these days. The old helmsman/sucunny /bridge boy system has gone and the average helmsman is an AB and in my experience usually a very good one
That’s not a mistake I’m likely to make since I literally posted that on March 28th.
Anyway this seems to be going in circles at the moment. So just to reiterate one of the points I was trying to make above is that in the absence and of specific info on the first breaker opening that caused black out of SS bus and loss of propulsion even at this stage of the investigation suggests to me it could be a very small issue in the breaker control circuits or on board the breaker frame itself.
Can I ask our American friends how high they rate the NSTB?
Having read a load of aircraft Investigations I find that side of it fairly good, note fairly.
How does the marine side rate?
Just for reference this is not an American bashing post as IMHO our very own MAIB ranges from excellent to absolute crap depending on the skillset of the invesigatigators .
Fair comment 244. I am still shaking my head over the appalling report published regarding the “Norwegian Prima” incident.
Digital protection relays as pointed out by AV above is where the settings are input for ‘short term, long term, instantaneous’ currents with the associated time delay curves. (TCC Curves). The breaker is designed to ‘trip’ via the protection relay only on current. All the others such as bus frequency, over/under voltage, reverse power is done via separate transducers and signaled to the breaker to trip possibly via the protection relay or through a shunt coil in the breaker. Remote closing is enabled via motor that charges the closing springs as soon as it is discharged.
A generator breaker cannot be closed until there is voltage upstream. This is where the UV coil comes in and is internal to the breaker. In the Dali’s case HR/LR breakers have this feature as well. HR is sensing voltage of the HV bus and LR is sensing voltage of the transformer secondary (440 upstream of the breaker).
Any bus voltage fluctuations due to generator or engine trouble will not be picked by the generator breaker current trip mechanism. But remember the little bugger UV coil? This is on a hair trigger and may trip the breaker (unexpectedly). No event log, no alarm. Possible the voltage fluctuation on the first blackout (remember lights flickering?) knocked out the HR transformer breaker via its built in UV coil.
Hogsnort - the ‘bomb’ you refer to may be what is known as ‘fusible links’.
BTW, they had all 3 motors operational at departure. No rudder movement after the blackout is still a mystery.
NTSB themselves say that their knowledge and experience in the marine side is limited. They do have Naval Arch/Hydro expertise … the keel squat theory for the grounding of the P&O cruise ship was from NTSB. Guess a very useful finding.
Hello AV2013
Very interesting single line. Aside from the redundancy, neat way to address the emergency switchboard feed. From the SGs and the TG easy to guess the lineage. Switchboard design redundancy probably influenced by company’s oil and Gas experience. And the best part is it really does not add any appreciable cost. Wonder why the other owners do not insist on this type of arrangement.
Looks like you have good experience in both sectors and very well informed - I now understand the reference to the FMEA. Good posts. Thanks.
Never seen a container ship anything like that personally. Is it a Triple E or something similar? I’m jealous of the redundancy.
Person - does the water feel wet to you?
Fish - what’s water?
I get the impression we have people that work on similar ships saying this is how they are wired, they always have been, and probably always will be, and then a few that have never been near one saying “That’s NUTS, way too easy to fail”.
YMMV
Can’t entirely rule it out, but it seems unlikely as the first and second blackouts were caused by different breakers opening. Keep in mind that the generator breakers that opened on the 2nd blackout were high voltage 6600v breakers while the first blackout was started by the transformer breakers opening, both the 6600v breaker before and the 440v breaker after the transformer. Perhaps the HR1 breaker and the DGR3+4 are the same model and experienced similar failures. Honesty the NTSB report raised more questions than it provived answers. At least it gave an accurate timeline for the events so this forum has something to speculate over for the next year or 2 .
Chief MAKOi’s summation on the report.
Dali is nowhere near the size of a Triple E,
100m shorter , At least 150, 000 tonnes lighter and a large amount of beam narrower. , sorry can’t recall exact dimensions of the beam.
Oh and a heck of a lot lighter draft.
Dali is a big ship but nowhere near being an ultra large.
Triple E
General characteristics
Type Container ship
Tonnage 196,000 DWT
Length 399.2 m (1,309 ft 9 in)
Beam 58.6 m (192 ft 3 in)
Draft 16 m (52 ft 6 in)
Propulsion Twin MAN 8S80ME-C9 engines, 29,680 kilowatts (39,800 hp) each at 73 RPM
Speed Design cruise: 16 knots (30 km/h; 18 mph) Max: 23 knots (43 km/h; 26 mph)
Capacity 18,270 TEU
Cost $185 million
General characteristics (2nd generation triple E)
Type [Container ship]
Tonnage 210,019 [DWT]
Length 399.2 m (1,309 ft 9 in)
Beam 58.6 m (192 ft 3 in)
Draft 17 m (55 ft 9 in)
Propulsion Twin MAN engines, 31,000 kilowatts (42,000 hp) each
Capacity 20,568 [TEU]
M/V Dali
General characteristics
Class and type [Neopanamax container ship]
Tonnage * 95,128 [GT]
- 52,150 [NT]
- 116,851 [DWT]
Displacement 148,984 t (146,631 long tons)[[4]]
Length 299.92 m (984 ft)
Beam 48.2 m (158 ft 2 in)
Draught 15.03 m (49 ft 4 in)
Depth 24.8 m (81 ft 4 in)
Installed power [MAN-B&W] 41,480 kW (55,630 hp)
Propulsion Single shaft; fixed pitch propeller
Speed 22 knots (41 km/h; 25 mph)
Capacity 9,971 [TEU]