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Anyone ever tried to put a MEP-003a engine on a MEP-002a?

storeman

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I am curious (assuming larger engine frame support can be solved) if anyone has ever tried to put a MEP-003a engine on a MEP-002a?

When does the gen-head max out? Its response to 9kw load is to lug the 002 engine. If a bigger engine, is the head capable of more output?

I have 4 rebuilt 003a engines and was thinking of experimenting.

Jerry :beer:
 

Isaac-1

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The question has came up before either here or on the SmokStak board, and I think the answer was yes they will bolt up. As to how much you can push out of a MEP-002a generator head, this is one of those questions with no real answer. At some point lets call it point Z you will instantly burn out the windings, the problem is before getting there you will have a point Y where you will be quickly doing damage to the winding insulation and a point X where you will slowly be doing damage. The real hard part to factor in is the question of how much has the insulation degraded since the generator end was built 25-35 years ago (meggers / insulation test meters may give you some ballpark idea, but really even they are best used to spot windings that are near their end of life, not to gauge remaining life), and how much can you stand running at point X within your useful life of the generator.

Ike
 

storeman

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Thanks Jim. I figured if anyone had tried, it might be you. Are you sure the max is the limit of the head versus limit of the engine?
Jerry
 

ETN550

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long post

Just my two cents here. And maybe because I'm an engine guy more so than a generator guru. Gen and engine are obviously two separate components each with their limitations. Which ever is the weak link determines the overall limit of the generator set as a whole. Personally, I would rather be limited by the engine not the generator.

The generator limit is determined by how much heat can be removed from the windings, including the exciter windings and main windings. Since only a small part of the winding is on the surface where the air cooling takes place the rest has to happen through conduction to the surface. So it is really hard to tell the core temp and when it is about to go. Cooling air temp plays a big part and altitude a lesser part. I suppose one could test the gen end at a variety of conditions taking it to its limit and recording the time it took to failure. Then slap on another head and do it again with increasing load, different air temp etc. The military tries to give some general guidelines with their derate tables.

The engine is subject to similar conditions with air temp and altitude, but also heating value of the fuel. Altitude is a larger factor for the engine than with the generator. Diesel fuel is very similar no matter where it comes from but if one were to run on kerosene mix or jet fuel reduced power could be noted. When the engine reaches its load limit one or a combination of a few things will happen. It may drop speed, and settle into a lower speed or it may die altogether. It may begin to black smoke (from not enough air being admitted for the given fuel setting) or it may overheat. Dropping speed is obvious, black smoke is visible providing there is daylight, and over temp may be measured. Overtemp is not really evident on the aircooled engines but the watercooled ones have temp gages. Temp gages could be fitted to an air cooled engine though. Most common are head temp gages for the air cooled engines. If fitted, one would have to know what the limit is and then watch it. Oil temperature can also be an indicator of overal temperature but could be misleading in cold weather. More meaningful in hot weather.

The engine gives us warning signs and usually a meltdown is not imminent. Often the engine will trudge along complaining by smoking, low speed, high temp for a long period of time. Certainly enough time to react and shed some load to help it. The generator on the other hand can hit a critical point and burn up very quickly without notice, other than maybe a funny smell that might precede the smoke. Once there is smoke the winding has been compromised. Winding resistance increases with heat so the controls must compensate by driving the excitation voltage higher and higher. As soon as the generator cannot remove as much heat as it is building up it will quickly become critical if load is not dropped.
 
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storeman

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etn550,
Thank you. I am sufficiently deterred from this experiment. Great info on heat buildup in the head. I hadn't considered it. Just thought I might squeeze 2-3 more kw out of the head with increased engine reserve power.
Jerry
 

Speddmon

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Feel free to do the experiment, but just keep the head limited to 5 to 7 KW so you know you won't overload it. You know you'll always have plenty of power so the engine won't bog down when starting a large load :grin:
 

steelypip

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Given that the engine is exactly twice as big as the 002a engine, I think twice the 002a idle fuel consumption is a good initial guess.

If I were serious about getting more surge capacity in the generator, I'd probably look at hanging a heavy flywheel off the blower end instead...
 

storeman

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Given that the engine is exactly twice as big as the 002a engine, I think twice the 002a idle fuel consumption is a good initial guess.
I kinda figured that out. No stats for unloaded consumption on either genny, so maybe load on 002a = half-load on 003a?

If I were serious about getting more surge capacity in the generator, I'd probably look at hanging a heavy flywheel off the blower end instead...



Not sure I understand your logic, except more engine mass added. Wouldn't it make the engine work harder ALL the time?
 

Speddmon

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Not sure I understand your logic, except more engine mass added. Wouldn't it make the engine work harder ALL the time?
More engine mass would allow it to continue to rotate faster during the momentary drag put on it when the large surge hits the generator. But you are correct, the engine would be working harder all the time with something like that done.
 

storeman

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Speddmon,
Tom,
I remember that thread now. I even saw my own awe-struck post there as a complete babe in the woods. Still am, I'm afraid, at least regarding the electricals. Thanks,
Jerry aua
 

steelypip

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The engine would not necessarily be working harder to spin a heavier flywheel at a constant speed. Why not? Simple: objects in motion tend to want to remain in motion. The only reason a heavy flywheel would present more 'drag' to a generator once at 1800 RPM would be because it had more surface area and thus more drag from air resistance.

Given that you could probably double the mass of the flywheel without changing its outside dimensions much, I doubt that this would show up in fuel consumption, especially given the huge amount of (usually) excess cooling air that goes through the blower.

Yes, the engine would have to work harder to get the flywheel up to speed. But once a flywheel is spinning at a constant speed, the only losses it has are bearing friction and aerodynamic friction. Here's an industrial application of the idea. You can think of the earth as a big flywheel that goes around once every 24 hours if it helps...

Basically, the heavier (really greater moment) flywheel would buy the governor more time to goose the injection pump and get the torque output of the engine up to deal with an increased load before shaft speed decreased.
 

storeman

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steelypip,
So, I could do a round lead mold and fasten it balanced within the fan and have the same effect as hanging another flywheel, without affecting clearance between fan and shroud?

Tom, If I upped the breaker to the one on the 10kw, I could possibly run at 7kw, managing load, with still some surge left?

Interesting. Guess worst case is damaging the unit. :?:
Jerry
 
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ETN550

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Not to rain on the parade but working through the physics of it on the flipside when the load is applied and it does speed down then the same amount of power with a larger flywheel will take longer to recover speed.

In essence the flywheel will only increase the time response it will not substantially change the lowest rpm reached during recovery. The governor action, if mechanical, is nearly instant because the mechanical linkage does not flex or stretch much (and we do not have smoke limiters, except turbo engines). The amount of fuel given to respond is proportional to the amount of speed drop. The droop setting can make this more or less. But some is always needed to ensure stability at steady speed. A trade off.

So in this sense the large engine on a small gen head would be much more responsive and have less droop when hit with a step load. Oversizing the engine is a classic solution to get tighter frequency control. In other words the large engine will hold rpm very well when hit with a big load. Not because of flywheel but because of ability to add much more fuel. Figure it this way: A 100% step load would require 100% fuel. Now double the engine with the same gen head and that same load is only 50% of the engine, yet the engine can respond with 100% fuel or twice the fuel as the small engine.

As far as witnessing the effect of extra mass just visit youtube and watch all the listeroid and lister videos on those 750 lb, 650 rpm 1400cc 6 hp engines and their little 3kw generators. Their response to load is pitifully slow and their drop in rpm is very noticable. Search Listeroid on youtube.

I would think that a quick recovery is as important or more so than the actual surge induced drop in voltage or frequency. Most equipment can handle a big drop if the duration is very short.

Another factor is the rpm of the unit. Although low speed is preferred for many reasons it does not lend itself to fast response. 3600 rom machines are inherently faster to respond than 1800rpm or those slow 650 Listers which are pitiful, but love them and would die for one anyway!

Good discussion keep it roling..2cents
 

storeman

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"So in this sense the large engine on a small gen head would be much more responsive and have less droop when hit with a step load."

That aspect is what prompted the idea in the first place. Thanks.
Jerry
 

storeman

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I think so if I can find the time.
Just won 4 more 003 engines today so I'll strip them and experiment with one. Lots of new/good dc vr's, starters, IP's injectors, glow plugs, stators, solenoids, etc coming available since I now have 10 rebuilt engines, Just need time.
Jerry :grd:
 

steelypip

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another long post

Not to rain on the parade but working through the physics of it on the flipside when the load is applied and it does speed down then the same amount of power with a larger flywheel will take longer to recover speed.
Sure - no free lunches. F always equals MA, which means that if you needed 10 KW-seconds to start your well pump, an MEP-002A will be running at full output for twenty seconds to come back up to speed after expending that energy. The good news is that the actual motor start demand for something like a two horsepower well pump is more like 10 KW for 100 milliseconds, which would be 1 KW-second, or full power for 1/2 second to recover.

The point is that you've taken a 100 millisecond load (locked rotor amperage on the motor) and spread it out over a second or two. That gives the governor a lot more time to respond and reduces the total amount of droop you're going to get.
In essence the flywheel will only increase the time response it will not substantially change the lowest rpm reached during recovery.
Um, no. If the instantaneous torque required to put x amount of current through the genhead is greater than the amount being made by the engine at that instant, then RPM drops. How far it drops is determined by a) the response time of the governor, b) the amount of time of the load, and c) the amount of instantaneous torque the engine can make, assuming the governor has noticed what is going on and is calling for maximum power. If we're talking about an MEP-002A engine, it probably makes about 16 HP at full power. If you need 17 HP or more for even a millisecond, the RPM will drop over that time span even if the engine is already making maximum power, which it almost certainly isn't.
The governor action, if mechanical, is nearly instant because the mechanical linkage does not flex or stretch much (and we do not have smoke limiters, except turbo engines).
'nearly' instant in a mechanical feedback control system is usually on the order of 50-100 milliseconds. Given that there are 3 power pulses on an MEP-002A per 100 milliseconds, you don't have a lot of opportunities to make more torque during a 0.1 second event unless your governor is really responsive. For the record: highly responsive mechanical governors tend to have bad oscillation and hunting problems. That's why there was a fancy high-tech version of several of the MEP generators that included electrical or electro-hydraulic governors for applications that needed high frequency stability (reduced surge and droop).
The amount of fuel given to respond is proportional to the amount of speed drop. The droop setting can make this more or less. But some is always needed to ensure stability at steady speed. A trade off.
All true. But you're really talking about two different things - the droop adjustment is used to minimize the amount of frequency (RPM) change from 0% to 100% load. Set it too sensitive and you get hunting. We're not talking about droop under continuous load, though, we're talking about time of response to a sudden load change. That's mostly governed by the friction, slop, and inertia of the linkage itself relative to the amount of energy stored in the governor spring, although the droop adjustment does have some effect on that as well. If it helps, consider that reducing the inertia of the governor linkage should increase the frequency of governor hunting (oscillation around the control value) when the droop adjustment is set sensitive enough that it allows hunting to occur.
So in this sense the large engine on a small gen head would be much more responsive and have less droop when hit with a step load. Oversizing the engine is a classic solution to get tighter frequency control. In other words the large engine will hold rpm very well when hit with a big load. Not because of flywheel but because of ability to add much more fuel. Figure it this way: A 100% step load would require 100% fuel. Now double the engine with the same gen head and that same load is only 50% of the engine, yet the engine can respond with 100% fuel or twice the fuel as the small engine.
Again,all true. Basically, you're making the engine capable of making more instantaneous torque with the same injector linkage position change- changing the slope of the governor response curve. If I'm humping five gallon cans of diesel fuel up the hill like I did in the snowpocalypse a couple years ago I think I'll skip the extra fuel consumption at no load, thanks.
As far as witnessing the effect of extra mass just visit youtube and watch all the listeroid and lister videos on those 750 lb, 650 rpm 1400cc 6 hp engines and their little 3kw generators. Their response to load is pitifully slow and their drop in rpm is very noticable. Search Listeroid on youtube.
I don't have to - I own one (a Metro clone of a 6-1 Lister CS). For the record: everybody with the Indian clones has to rework the governor linkage because of sticking and droop problems Dry lubed Heim joints are your friend. Real Listers are better just because the governor was properly set up to begin with, but Lister didn't sell or recommend this engine as a generator engine - they modified it into the Start-O-Matic, which was the UK version of a Delco-Light, and included much heavier flywheels (350 lb each versus about 100 lb each on my clone) on the engine as well as a massive generator pulley as part of the package. Inertia is pretty much the only way to beat the fact that you have five power pulses per second, more or less.

I would think that a quick recovery is as important or more so than the actual surge induced drop in voltage or frequency. Most equipment can handle a big drop if the duration is very short.
Well, maybe yes, and maybe no. My (fancy, new) heat pump complains if things go too far out of spec, flags the power as unstable, and won't start the compressor until it has been stable for a sufficiently long time (minutes). My battery-inverter UPS systems also complain vociferously at motor-start-induced frequency and/or voltage sags.
Another factor is the rpm of the unit. Although low speed is preferred for many reasons it does not lend itself to fast response. 3600 rom machines are inherently faster to respond than 1800rpm or those slow 650 Listers which are pitiful, but love them and would die for one anyway!
They're pitiful as delivered - the Indians use them for irrigation pumps, and really don't care if they're 20 RPM fast or slow at any given time. When you optimize them as gensets they really do a very good job - we have people who've put many thousands of hours on one as a baseline load machine and yes, they do wear out, but they're very cheap and easy to fix. And because they're water cooled, they're perfect for heating domestic water, too.

The big gotcha is that, at the end of the day, a 6/1 really makes only six horsepower at 650 RPM. It can fake you into believing that it can do a lot more because of the huge flywheels (A 6/1 with a 5 KW ST genhead will happily start a 5 HP air compressor), but continuous load had better not exceed 3 1/2 KW or you get smoke and sag for your trouble.

The neat things about a CS (or clone) are that they're quiet (well, easily made quiet anyway), pretty efficient (evacuated crankcase, so the FHP is pretty good), and omnivorous. They'll eat anything that a multifuel will. I want to put ceramic coating on the piston top, chamber top, and precombustion chamber and see if I can get the BSFC down a little more.
Good discussion keep it roling..2cents
Agreed. Sorry for the delay - this fell off my watch list somehow.

steelypip,
So, I could do a round lead mold and fasten it balanced within the fan and have the same effect as hanging another flywheel, without affecting clearance between fan and shroud?
I'd be worried about restricting cooling air flow. Also remember that energy storage is proportional to distance from the crank, so on the inside of the flywheel where the magnet ring is might work. Of course, there's the concern about structural overload, etc to consider.
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