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Generator wet stacking discussion

glcaines

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Changing the crankcase oil on a frequent basis will eliminate problems with fuel diluting the oil. I have an MEP003A, which is a 10 KW unit that serves as a whole-house backup and is used on a fairly frequent basis. I have never had issues concerning wet-stacking but I still change the oil every six months. I also don't get conservative when running the generator. I turn on lights, dryer, washer, HVAC, ovens, etc., whatever is needed. I can tell what the load on the generator is just by listening to it and not even looking at the load meter. When it's working hard, all is good. Knock on wood, I have never had any problems with this genset after years of use.
 

snowtrac nome

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So how much different is the genset engine compared to a diesel in a truck especially those that make short local trips? People put cardboard in front of the radiator to increase
the engine temperature. Is that more to increase the heat in the truck or to help the engine a little. Granted it doesn't help the exhaust gas temperatures but I would
think having the engine run at proper temperatures would help keep the valves (maybe), rings, etc seated properly.

I am referring to this SS thread: http://www.steelsoldiers.com/showthread.php?162826-M1008-Not-Reaching-Running-Temp

its very different first your truck doesn't have safety circuits to shut down if the engine gets too hot. automotive engines also run at a variety of rpm's from idle to wide open throttle the gen set sits there and purrs at 1800 rpm and the cardboard is for heat. I object to this redneck engineering especially with an air to air after cooler. on the larger class 8 trucks you can feel the horse power difference with a winter front on. in my mind there is no substitute for a good thermostat which it sounds like his is good he just needs more load so the engine is fed more fuel creating a higher combustion chamber temp.
 

Daybreak

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So how much different is the genset engine compared to a diesel in a truck especially those that make short local trips? People put cardboard in front of the radiator to increase
the engine temperature. Is that more to increase the heat in the truck or to help the engine a little. Granted it doesn't help the exhaust gas temperatures but I would
think having the engine run at proper temperatures would help keep the valves (maybe), rings, etc seated properly.

I am referring to this SS thread: http://www.steelsoldiers.com/showthread.php?162826-M1008-Not-Reaching-Running-Temp

Howdy,

A lot of things. A diesel generator is / was made to run at 1800rpm loaded or not. A vehicle starts and idles. You go from a stop to 50 miles an hour and you have loaded the pistons and rings. The fuel delivery is different. It is not so much as the scavenged heat, as it is the explosion of fuel in the chamber. Under load, you have a complete fuel combustion. When there is no load, or small load, the fuel pumps in, with a simplistic fuel delivery system. You do not have a complete combustion process, and the extra fuel starts to glaze the piston walls, loading carbon goo and unspent fuel in the exhaust manifold and muffler. Even if you have the system wrapped up tight, and the ambient temp around the engine was 220 degrees would not make it not wet stack.

The only true similar diesel truck engine would be like v92 detroit screamer.

Brand new designed diesel engines in todays generators use a more advanced fuel delivery and other advanced technology to lessen the problems of wet stacking.
 

Dwnorton1

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Thanks to everyone for a very good discussion on wet stacking, very informative and much appreciated. Only thing missing is Guyfang's input on the subject. Love the stories.
 

rustystud

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its very different first your truck doesn't have safety circuits to shut down if the engine gets too hot. automotive engines also run at a variety of rpm's from idle to wide open throttle the gen set sits there and purrs at 1800 rpm and the cardboard is for heat. I object to this redneck engineering especially with an air to air after cooler. on the larger class 8 trucks you can feel the horse power difference with a winter front on. in my mind there is no substitute for a good thermostat which it sounds like his is good he just needs more load so the engine is fed more fuel creating a higher combustion chamber temp.
Actually closing off the radiator to outside air flow is not really redneck engineering. Manufacturers have installed "louvered" radiator fronts for over 70 years. My old 1941 IHC had one. So it just depends on the weather conditions. You cannot expect a truck running up to the oil fields in sub-zero weather to keep warm with all that cold air flowing around it. I used that example as your from Alaska. The opposite is also true. When it's hot, trucks have a fan to help air flow through the radiator. The thermostat cannot handle all the heat and cooling requirements of the engine, nor was it designed to. It is as they say a "joint effort" . The whole object of any cooling system is to keep the engine at the optimum operating temperature, where fuel consummation and power are at it's best. If that takes a cardboard in front of the radiator, so be it.
 
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craigc

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The controllers some of us are using can do Load switching (load shedding and dummy load outputs) this would work to automatically keep your genset loaded at 60% or whatever you program it too.
 

flydude92

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rustystud

If you can maintain the engine temperature of a diesel engine if it is in a generator or truck
will help the engine last longer since it is running at its designed temperature even if it is running at light loads?

Providing of course you run at full power once in a while to burn off excess fuel buildup in the exhaust system?
 

Guyfang

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I was a 52d wet stacking is caused by incomplete combustion raising the t stat temp wont help a lot. the other problem is the tqg series gen sets had a highly restrictive exhaust muffler which added to the problems caused by wet stacking your generator will run at max efficiency at 60 percent load. my suggestion would be to create a variable load bank a simple way to do this would be with an electric heater and depending on the load you have you can selectively turn on coils in the heater. I would not restrict cooling as you will still have still have the same fuel charge that isn't burning all the way across the top of the piston.
We had this problem in HAWK and PATRIOT. The gen sets were simply too big for the job, 98% of the time. Its that 2% that was the killer. But I am getting the cart before the horse.

Some smart TROSCOM guy, thought that what was needed to combat this wet stacking problem, was a parasitic load bank. The operator would turn on the load bank, after the gen set had been put on line, to "help" the engine stay clean. The 15 and 30 KW gen sets had a heater/load bank contraption mounted to the front of the set. The air being drawn through the gen set, from the rear louvers, past the main AC to cool it and then past the engine, through the radiator, to cool the engine, and at last through the load bank, to cool it. Man, that was a run on sentence. Anyway, that was the way it worked. Or was suposed to. By the time the cooling air made it the whole way through the whole rig a ma roll, the cooling air wasn't so cool. The load banks tended to overheat, causing the components to become brittle and break. That was problem number one.

Number two, was the contraption was parasitic, so it was in addition to the load the gen set was pulling. I will use Patriot here as an example. The launchers each had a gen set on it. Each gen set was a 15 kw set. The launcher HAD to be powered up at all times. It pulled about 7-8 KW, if I remember right. It ran like that 24/7. Maybe 50% load. So on goes the load bank. You could step it up in 2.5 KW steps, to about 7-8 KW, ( cant remember the correct KW readings and am to lazy to look right now) so you could give the set a full load.

Sounds good in theory. But what happens when you are chugging along, with 80-90% load, (launcher and load bank) and the missile launcher gets a firing command. All kinds of electric gear starts sucking up power! And then the crowning step. The launcher goes into Super Elevation, (this is where the launcher jumps up, and slews to the right or left, to "lead" the the target, like shooting quail) so the bird can leave the launcher. The gen set then hits 130-140% load, and shuts off in the middle of the firing run.

And to make it even worse, in the winter, heaters in the launcher raised the load even higher. So to compensate, you had to lower the load banks setting, or turn it off. So who needs it? No one. The darn things were never turned on. Or only when people were sure you might not need to shoot someone down. All well and good, but when we were protecting the skies, who was to say you could or could not take time out to run it? When a Patriot battery was non mission capable, phones rang in the Pentagon. So no one was going to make such a decision. HAWK was the same way. As soon as the system went into high gear, the load back caused the set to overload and shut off.

Now lets substitute your house with a missile system. The set is running, house is 3 KW, you put 1.5 KW on with your load bank and everyone is happy! The old lady pushes the toaster down, Daughter #1 turns on the dryer, Son # one turns on the dishwasher, and you're all standing in the dark.

The only way to beat this circle, is to have a load measuring system, that senses the up swing of an increased load, and kicks out your load bank. And what happens when the hot water heater kicks off, the dryer kicks off and your back to 2.5 KW? Either you have to manually reset your load bank, or your "smart" load sensing circuit turns the load bank back on. This might be expensive. And it would have to work super fast! I am sure its doable, and the new computer systems do this, or something like this now, but like I said, expensive. Much easier, and less expensive to every once in a while hook the gen set up, run it an hour or two and clean it up. Diesel Addict and post #10 says it all.
 

Guyfang

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My reading suggests that it becomes a problem fairly fast (a few hours?), but that periodically loading it will clean it out.

http://m.csemag.com/index.php?id=95...=36382&cHash=e0b399904af236d9f863742ca8f03440
Not that fast. I have often said, you all are never going to run your sets like the military. 24/7 for weeks and months at a time. How many hours do you run a year? Not anywhere enough. And if you need backup for a few weeks, well, when its over, burn it out in ahour or three with a load bank. Look again at message #10.
 

Guyfang

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Howdy,
You say it runs at 180 degrees now. In the middle of summer, or ambient temp 80 or higher, it will be around 200.

Wet stacking is not so much a temperature issue. The simple method of a 1800rpm engine without advanced fuel delivery. Because the fuel delivery is simplistic, a load considered to be...er.. its listed somewhere, like 60% or higher will make a more complete fuel burn. 50% or less can lead to wet stacking

Wet stacking is caused by unburned fuel. The combustion process is not complete. That is also why it can be cleaned up with a good hard load. Diesel engines like to work.

MEP-8xx wet stack info

working some TQG on a load bank. I also made some logs with temps and conditions

Acquired a Military surplus load bank

Best case is 75-85% load. You can run it higher, as long as no unexpected load pops up
.
 

Another Ahab

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The only way to beat this circle, is to have a load measuring system, that senses the up swing of an increased load, and kicks out your load bank. And what happens when the hot water heater kicks off, the dryer kicks off and your back to 2.5 KW? Either you have to manually reset your load bank, or your "smart" load sensing circuit turns the load bank back on. This might be expensive. And it would have to work super fast! I am sure its doable, and the new computer systems do this, or something like this now, but like I said, expensive. Much easier, and less expensive to every once in a while hook the gen set up, run it an hour or two and clean it up. Diesel Addict and post #10 says it all.
You'd think something as simple as like a reverse-capacitor (if there even IS such a thing) could handle this problem handily and inexpensively.

The problem (on the surface of it) seems simple:

- A device that promptly/ instantly recognizes a surge load, and then by predetermined hierarchy sheds less-than-critical loads to level the demand.

I'm not an electrical engineer, or an IT programmer, but is there anybody on here who can address this thinking; am I speaking totally out-of-school about all this?
 

Guyfang

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These things exist. Craig could program it I am sure, into his remote start setup. We use something like this here in the photo electric world. I for the life of me dont kno the english name of it, as I have only installed/used it here and its called an SPS. Its for all intents and purposes, a small computer.
 

Dwnorton1

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Craig and I were discussing load shed earlier. His controllers are capable. Some programming and a 24vdc control powered contactor. Probably a two pole 25-30amp contacts. I think it should be fast enough. Our control system offshore has multiple layers of load shedding capabilities, should be adaptable to his controllers and fast enough to dump your scavenger load as it sees new load.
Do we need to go to the trouble when you can just exercise machine, probably not. Is it cool that we can. Absolutely. Are we going to try. You know it!!!!
 

craigc

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The controllers we are using can easily do that, setup 4 or so 1.5kw dump loads. Have the controller monitor amp draw and when there is no load on the genset switch all 4 loads on for a 6 kw load. Then as actual demand increases start disconnecting 1.5kw at at time based on actual load with a target of say 6kw. Also there is a actual PLC functionality in the PC software to write ladder logic and the controller is basically a PLC. You can write your own logic if the controller doesn't already have the functions you want.

Hope these screen shots are readable.

DSE7310-2.jpg

DSE7310-1.jpg

Sent from my STV100-1 using Tapatalk
 
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Guyfang

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That's what I like! Do it cause you can. Not because you have to.

When I was in trade school here, the SPS was brand new. Programing was like voodoo. I could make things work in the lab after about 100 tries. We had a kid in class with me, a dud. His name was Mirko. The boy could not do ANYTHING right. Nothing. He was at the same construction company as I, and I was his guardian angel. Our master electrician told me to be this kids boss, keep him straight, get him through school without killing himself, or someone else. Then after 6 months, the company could send him away. My plate was full with him. Then we went into the lab for the first day of programing. Naturally none of us could find our butt with a hunting dog and a flashlight. Except Mirko. By the second week, the teachers could not keep up with him. Unreal. He didnt even have to try. Sadly, he was so dam* lazy that he works as a roadie for a heavy metal band, instead of programing. What a waste.
 

Another Ahab

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Our master electrician told me to be this kids boss, keep him straight, get him through school without killing himself, or someone else. Then after 6 months, the company could send him away. My plate was full with him. Then we went into the lab for the first day of programing. Naturally none of us could find our butt with a hunting dog and a flashlight. Except Mirko. By the second week, the teachers could not keep up with him. Unreal. He didnt even have to try. Sadly, he was so dam* lazy that he works as a roadie for a heavy metal band, instead of programing. What a waste.

:naner::funny:
 

Another Ahab

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You'd think something as simple as like a reverse-capacitor (if there even IS such a thing) could handle this problem handily and inexpensively.

The problem (on the surface of it) seems simple:
The controllers we are using can easily do that, setup 4 or so 1.5kw dump loads. Have the controller monitor amp draw and when there is no load on the genset switch all 4 loads on for a 6 kw load. Then as actual demand increases start disconnecting 1.5kw at at time based on actual load with a target of say 6kw. Also there is a actual PLC functionality in the PC software to write ladder logic and the controller is basically a PLC. You can write your own logic if the controller doesn't already have the functions you want.
So the problem isn't really THAT hard or expensive to solve, right?
 

DieselAddict

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Here are my thoughts on wetstacking.. Strictly my opinions based on a reasonable amount of experience running/fixing MEPs and being system owner of 2MW of diesel generators at work for more than 15yrs.

Without a doubt if you idle your generator for long periods you are going to cause problems. It is basic physics. Diesel engines are very heat efficient and without load they don't make a lot of it (heat). Low heat means incomplete combustion. Low heat in the presence of condensable gases (unburned fuel and water vapor) is a recipe for bad things to happen.

There are conditions that will make this worse. Bad injectors, incorrect timing, low cylinder compression, **** even a partially clogged air filter are all things that will make the engine not burn fuel efficiently which will increase wetstacking potential. My point here is that a correctly running engine with good fuel delivery will not wetstack as quickly as one with problems. This is why (in my opinion) everyone should KNOW the condition of their set. One of the best ways to get a lot of info with low effort is oil analysis. You'll want to do more than one on a single oil change. You need at least 25 hours for the first sample and at least 50 hours on the second. Look for trends in your fuel accumulation. If you are quickly accumulating fuel, your set has an issue that will increase your wetstacking potential. If your fuel accumulation is low your wetstacking potential is lower.

Wetstacking potential management: Knowing the condition of your set will tell you how to mange its wetstacking potential. If you have a set that accumulates fuel quickly in the oil you may have to go after some kind of constant load mechanism as is being discussed here (assuming you can't resolve the issue causing the problem). If you have a set that accumulates very little fuel in the oil you may be wasting resources in the form of extra fuel or in the cost of building an automatic dummy load. Regardless of the condition of your set you can minimize the potential of the exhaust condensing gases by simply insulating everything. You'll reduce temperatures inside the cabinet and overall do only good for the set in the long run. Why don't they already come that way? Money, Plain and simple. Insulating the exhaust will not change the cylinder conditions much. I think the issues with cylinder washing in diesel engines is not as severe as it is in gas engines.

If you have a good running set with low fuel accumulation in the oil its likely you need to do NOTHING about its wetstacking potential. And by nothing I mean nothing extraordinary. You still need to load test your set on some a basis that gives you confidence it will work when called upon. For me that means yearly. I'll accumulate between 30 and 50 hours MAX a year on my main set (weather depending). The more lengthy outages for me come in the winter (another factor that increases my wetstacking potential). Until recently my main set was a MEP-003. The base load for my house is 600w. I have to try to get it over 8kw. The vast majority of the time its under 1kw. I acknowledge that the 003 has a lower wetstacking potential due to its design versus the 80x machines, but just for conversation sake I can say that running it for hours on end with under 1kw of load on it didn't hurt it at all. I load tested the crap out of it before delivering it to my neighbor to use on his farm and I can say that it showed virtually no signs of wetstacking. It handled a 10kw being dropped on it without missing a beat. It smoked a little but it cleared up in a few short minutes to a steady light haze.


On the flip side I've bought several MEP-802s at auction that were so severely wetstacked that they wouldn't support more than 50% load without falling on their collective faces. Even the worst one I've encountered cleared up and would pull 6.5kw resistive load with less than 4 hours work. These things were smoking so badly that I was concerned they would catch fire. We are talking about really severe wetstacking on the scale I expect a member of this forum to NEVER cause in a unit under their care. To get these units cleaned up took a few gallons of diesel and some of my time. None of them have failed to run for their new owners. The one that was the worst is now at my brothers house and works great for him. I shake my head at him because he has an electric string trimmer and he runs it off the generator for fun. He adores that thing. When I load tested it in the fall it was fine.


Unless you idle your set for a couple hundred hours or you have one of the mechanical problems I mention above I really don't think you are going to encounter this condition on a scale that a 30-45 min run on a load bank doesn't clean up. If you run a load of clothes through an (electric) dryer or bake a ham while you are on generator power my money is on NEVER seeing the problem.


From a pure fun standpoint building an auto-load bank is awesome. I totally support the spirit of the endeavor. I can't wait to see what you come up with. I doubt there is a lot of need for it but its very cool.
 

DieselAddict

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The controllers we are using can easily do that, setup 4 or so 1.5kw dump loads. Have the controller monitor amp draw and when there is no load on the genset switch all 4 loads on for a 6 kw load. Then as actual demand increases start disconnecting 1.5kw at at time based on actual load with a target of say 6kw. Also there is a actual PLC functionality in the PC software to write ladder logic and the controller is basically a PLC. You can write your own logic if the controller doesn't already have the functions you want.

Hope these screen shots are readable.

View attachment 669448

View attachment 669449

Sent from my STV100-1 using Tapatalk
I am going to have to snag one of these to play with. :)
 

craigc

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how about 3 or so of these in a nice aluminum enclosure with insulation and 220VAC fan and a partition on one end to keep the contactors/relays away from the heat. I bet between all the smart people on this site we could make a Dummy load bank for a reasonable price AND we'd have a load bank for testing any new gensets we buy :)

http://www.globalindustrial.com/p/h...strip-heater-osf15211900b-1900w-240v-21-x-112

The controllers are here and the software is free, you can register for free to download the software or documents. They have many different types with different function. I had 2 left over from a job about 4 years ago so thats how I learned about them, I have nothing to do with the company or sales of these.

Beware there are chinese copies of these controllers and I think they cost about the same as authentic DSE, but they don't have a serial number so you won't get any support from DSE or be able to connect to their free remote monitoring web site called dsewebnet.
https://www.deepseaplc.com/
 
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