Stator failure- Northern Lights 6kw

[tanglewood]

Originally Posted by Dockhead

Ah, yes, but this is not American 220v split phase @60hz. This is European single phase, at 50hz.

The engine speed is reduced to 1500rpm from 1800rpm and the power is reduced, if you switch it over from U.S. to European power. On my generator, from 8kW to 6.5kW.

Agreed. I read your original inquiry as a two part questions, but sounds like it wasn't. I thought the two parts were 1) impact of reducing speed from 60hz to 50hz, and 2) impact of operating at 110V and 2x the current vs 230V and 1x current.

I was addressing part 2, which perhaps exists only in my imagination.

I completely agree about part 1.

[DotDun]

Originally Posted by Dockhead

Bit (still more) of thread drift, but here's a question about generator heads and stator temperatures --

Most generators can be configured to produce either 110v @ 60hz or 220 @ 50. They produce less power in their 220v configuration because the engine runs at 1500RPM instead of 1800RPM.

So the same generator head is being used to produce about 25% less power, but then a bunch less amps, since the voltage is double. Less than half of the amps. Is the thermal load on the generator head related to power produced, or to the amperage?

If the latter, then in 220v mode these generators will be massively derated, no?

Thermal load is related to power, not amps.

When it's producing 110v and 50a (5500w) it's actually producing the same heat as producing 220v and 25a (5500w). In the 110v configuration, you are paralleling the windings, in the 220v they are configure in serial. Hence, each winding is producing the same amount of power.

The thermal savings is due to slowing down the unit to get 50hz vs. 60hz.

[Dockhead]

Originally Posted by a64pilot

. . .Water cooling anything has usually several advantages, much easier to regulate temp and it is easier to maintain a more even temperature, and you can remote mount the heat exchanger (radiator)
However water cooling is usually more complex with more failure points
I'm no computer guy, but don't high speed computers use liquid cooling now?

Water cooling is great, because water can carry about 4000 times more heat than air, per unit of volume. So you can transfer heat from one place to the other with far smaller volume of the cooling medium.


But we have not been talking about water cooling anything but more air. If it were possible to water cool the alternators and the generator heads, it would greatly reduce the engine room temperature problem. But we've just been talking about processing the engine room air to cool it down, versus just blowing in already naturally cool air. The water is great for carrying the heat, but you still have to blow around air, in order to transfer heat from air to water. You have to recirculate larger, and depending on the size of the heat exchanger and temperature differences involved, maybe much larger volumes of air, to get the same cooling effect as a given volume of naturally cool air, if your water temp is the same as the ambient air temp.

[tanglewood]

Originally Posted by DotDun

Thermal load is related to power, not amps.

When it's producing 110v and 50a (5500w) it's actually producing the same heat as producing 220v and 25a (5500w). In the 110v configuration, you are paralleling the windings, in the 220v they are configure in serial. Hence, each winding is producing the same amount of power.

The thermal savings is due to slowing down the unit to get 50hz vs. 60hz.

There you go. Parts 1 and 2 of the questions - at least as I read it, and apparently DotDun as well.

[Dockhead]

Originally Posted by DotDun

Thermal load is related to power, not amps.

When it's producing 110v and 50a (5500w) it's actually producing the same heat as producing 220v and 25a (5500w). In the 110v configuration, you are paralleling the windings, in the 220v they are configure in serial. Hence, each winding is producing the same amount of power.

The thermal savings is due to slowing down the unit to get 50hz vs. 60hz.

That makes sense; thanks.

[DotDun]

Originally Posted by Dockhead

Water cooling is great, because water can carry about 4000 times more heat than air, per unit of volume. So you can transfer heat from one place to the other with far smaller volume of the cooling medium.


But we have not been talking about water cooling anything but more air. If it were possible to water cool the alternators and the generator heads, it would greatly reduce the engine room temperature problem. But we've just been talking about processing the engine room air to cool it down, versus just blowing in already naturally cool air.

I believe Fischer-Panda has water cooled generator head on some models......don't know if it has a separate heat exchanger our shares the fresh water from the engine.

[Dockhead]

Originally Posted by tanglewood

Agreed. I read your original inquiry as a two part questions, but sounds like it wasn't. I thought the two parts were 1) impact of reducing speed from 60hz to 50hz, and 2) impact of operating at 110V and 2x the current vs 230V and 1x current.

I was addressing part 2, which perhaps exists only in my imagination.

I completely agree about part 1.

Actually I was indeed asking about your Part 2. Dot Dun seems to have answered it.

[Dockhead]

Originally Posted by DotDun

I think you demonstrated the main point. As tanglewood stated, you can't get enough air into the engine room. On your boat, you stated the engine room air is 10C above outside air. If you could get 'enough', it would be the same temperature as outside air. Since that is the 'sink' to start cooling the generator, you'll always be at least 10C higher temperature inside the generator compared to raw water cooled. Plus you are burning what? 250W? running engine room blowers? The raw water is "free". That is not more efficient (using 250W and have a 10C hotter generator).

I believe you can design a system to move/circulate a lot more air inside the engine room than you can bringing in outside air. The amount of outside air you can bring in is restricted by the openings, both entrance and exit, that have to be shielded from bringing in water (rain, green, etc.)

But, that's an experiment for someone who has an engine room heat problem.....I have no blowers nor a hot engine room....

There's a fallacy here, I think --

Say the cooling effect of a given amount of fresh air keeps the engine room temp to ambient +10. But that doesn't mean that this cooling effect is "not enough". On the contrary, this is quite good. Usual standard for engine rooms on large power boats is +30F.

To get the same cooling effect recirculating air over a heat exchanger, with water temp = ambient air temp, you must circulate MORE air over the heat exchanger, maybe many times more.

That's because no matter how big the heat exchanger is, and how much 20C water you circulate through it, you will never get 20C air coming out of the other end of it. Maybe many times more air -- double, triple, 5x, depending on the amount of heat you need to move and other parameters of the system.

Heat exchangers produce resistance to air flow through them by the nature of how they work (contact of the air flow with the vessels containing the water). Maybe some really big heat exchanger might have less resistance than some really horrible duct work, but it's hard to imagine. Plus remember you will be moving greater volumes of air through the heat exchanger, than you will need to move through a duct.

So in any case, you're going to spend more energy moving air over the heat exchanger to create cooler air, than it will take to bring in air which is already naturally cool, and cooler than what you can ever manufacture with a heat exchanger using water at the same temp. Then moving the water through the heat exchanger also costs energy.

Maybe worthwhile as a desperate measure in a boat so badly designed that there is really no way to increase the duct area. But I guess in 99% of boats, you can run another duct through a transom or just chop a hole in the deck, increase the size or number of the blowers, and get a much better cooling effect.

[DotDun]

Originally Posted by Dockhead

There's a fallacy here, I think --

Say the cooling effect of a given amount of fresh air keeps the engine room temp to ambient +10. But that doesn't mean that this cooling effect is "not enough". On the contrary, this is quite good. Usual standard for engine rooms on large power boats is +30F.

To get the same cooling effect recirculating air over a heat exchanger, with water temp = ambient air temp, you must circulate MORE air over the heat exchanger, maybe many times more.

That's because no matter how big the heat exchanger is, and how much 20C water you circulate through it, you will never get 20C air coming out of the other end of it. Maybe many times more air -- double, triple, 5x, depending on the amount of heat you need to move and other parameters of the system.

Heat exchangers produce resistance to air flow through them by the nature of how they work (contact of the air flow with the vessels containing the water). Maybe some really big heat exchanger might have less resistance than some really horrible duct work, but it's hard to imagine. Plus remember you will be moving greater volumes of air through the heat exchanger, than you will need to move through a duct.

So in any case, you're going to spend more energy moving air over the heat exchanger to create cooler air, than it will take to bring in air which is already naturally cool, and cooler than what you can ever manufacture with a heat exchanger using water at the same temp. Then moving the water through the heat exchanger also costs energy.

Maybe worthwhile as a desperate measure in a boat so badly designed that there is really no way to increase the duct area. But I guess in 99% of boats, you can run another duct through a transom or just chop a hole in the deck, increase the size or number of the blowers, and get a much better cooling effect.

And it's this claim of inefficiency that I questioned earlier. My generator is using the same fan as yours (alternator fins). Hence, the fan on my generator moves the same amount of air that the fan on your generator moves. My heat exchanger has 420cm2 of opening which is the source of air for the fan, I believe this is close to the size of the intake vent on the side of your generator. The air in my generator runs 15°F above the cooling source (raw water). I'll bet yours is no better. Hence, I don't buy the level of inefficiency with heat exchangers that you propagate. It's all in the design of the heat exchanger, i.e. cm2 of fin area.

[Pelagic]

My understanding is that the primary purpose of the Fresh/Salt water heat exchanger is to cool the engine block and (wet cool with raw water) the very hot exhaust gasses in a marine installation to maintain optimum temp.

That a well designed engine room brings in a large amount of outside fresh air normally directed to wash under the cooler skin plates of the bilges, before a large portion is consumed by the air intakes and combustion of the running engines.

That with all engines running, your fresh air intake should be slightly less than the engine room's exhaust fan capacity, so that a slight vacuum is felt when opening the ER door.

That is why ER fans generally have variable speeds on the intake and exhaust fans of a well insulated engine room to keep that internal air balance, depending on what engines are running.

[wwarrington]

Anyone have any luck getting NL to honor their 4+1 warranty? I have a M673L3with just over 1600 hours on it and am looking at a possible stator failiur as well. But this time from corrosion. From the start I had all sorts of issues with this unit. Factory installed on a brand new Hylas 48, I figured that with all the necessary maintenance suggested done on the hour, Id have a trouble free genset for at least a few thousand hours. Well after the first oil change I arrived in the Galapagos to find the entire generator compartment sprayed with oil. Thinking that maybe i just didnt tighten the oil filter enough and that the oil levels never dropped I moved on. Next an obstruction to the air intake that occured somewhere in the rear panel caused the engine to stall out. Finally a mechanic in NZ found a factory piece of foam was the obstrution. Then last year in Fiji the raw water pump started leaking from the mechanical seal. It wasnt a huge leak but enough to overflow out of the housing and into the engine compartment. Thankfully I had a spare onboard and changed it out immediately. During most of this time I found that the hose from the nipple at the radiator cap to the coolant resevior would regularly crack off. Id check the coolant levels, top off if necessary, cut of the burnt end of the hose with the slack and reattach. By the end of last season the genset was running fine but found that there was some salt crystals on the metal screen covering the flywheel and that the resevoir overflow would dump pink coolant directly into the genset housing and not outside. At the end of the season I put her on the hard and had a local mechanic do a full service on this and my 80HP Yanmar (750hrs only). Due to some drama on the homefront I didnt make it back to the boat for 9 months. I know I know. never leave your baby that long. The Yanmar stars right up and we splash her. So looking forward to firing up the genset so I can run the AC because Its hot as hell here in Fiji right now and no go. First, starter motor is spinning but not catching. Local mechanic removes, cleans up a significant amount of corrosion and bench tests it. All good except the corrosion has seized the flywheel. The boys had to actually separate the engine from the generator in order to free her up which took a few days in ungodly heat but they did. Put her back together and the engine starts right up. Put a load on her after warm up and she puts out 125VAC per the panel. turn on the main AC unit and she trips the AVR 30A breaker which also has happened from time to time over the past 2 years but usually when there is increasing load on her. We reset it, turn on the AC and i am in heaven...for about 2 hours. Engine running fine but no AC output. try reseting all of the breakers and nothing. Time to contact Northern lights. They say it is either AVR,Loss of residual magnetism in the excitation winding or Faulty connections in J-box. We test resistance between J/K and its high. Then inspect the windings in the rear which is hard to access and find that one of the brush assembleys has fully disintegrated. We think we have found the problem. It takes almost 10 days to receive the part using Fedex priority intl. Still no AC output and now the resistance bw J/K is even higher.

I have emailed NL twice, called twice since monday and feel like either they are ghosting me or completely overwhelmed with other service requests. Next step I feel is to remove the generator and do a thorough cleaning/ inspeciton of the Stator. According to their 4=1 warranty a part such as this should be covered, but not labor. Has anyone on here had any positive or negative experiences getting big number parts covered under warranty? The Hylas service rep, who very knowledgeable and responsive has only dealth with smaller part replacements like relays and switches.

Sorry for the long post, but at this point its part of my therapy to keep me from jumping overboard.

[Kennyk]

Is it possible to remove a NL generator from an island packet