Convert MEP-803a to Inverter?

[Thermoguy]

After evaluating my emergency backup power options deep in hurricane country I concluded that diesel is king for my 10KW demand to be split between two existing 5KW manual transfer switches (about 80 ft apart - house & barn) that were originally powered by separate, always problematic portable gasoline generators. My work is cooling diesel and NG fired big iron prime and standby power in the harshest environments, so "robust design" is my specialty. My ideal rig would be diesel inverter versus generator, but diesel inverter pickings are slim and $$$ for only backup/occasional service. Then the Fermen MEK-803a showed up on my radar ... WOW! True, it's not an inverter, but for sure tactical, diesel and Mil-spec design checks some major boxes IMO. I pulled the trigger on one clean (enough), straight (enough) and low (enough) Hobbs and so far all systems are thumbs up for only brief unloaded power-ups to avoid wet-stacking. Just in are the AVR FNQ_R-3 fuse and holder and MOV varistor to upgrade my (older than 2009) Fermen. On the drawing board is to build a 12KW, 55 gal drum +6 x 2KW CB switched heaters hot-water load bank to verify power integrity with particular attention to brushless AVR response. I hope to scope the output and will verify fuel burn, etc. So, that's my pre-ramble.
The title begs the burning question. Yes - No - Maybe So? Mechanical is my world. I'm comfortable enough in the 'sparks and wires' world to troubleshoot and swim in the shallow end and I have all the tools AND there is that sign on my wall that does say "BE CURIOUS", but will inverter conversion require major surgery on the generator or is there a simpler 'work-around'? Also, it remains to be determined about just how good is the existing AVR (with upgrades) and especially resulting wave form factors.

 

[peapvp]

After evaluating my emergency backup power options deep in hurricane country I concluded that diesel is king for my 10KW demand to be split between two existing 5KW manual transfer switches (about 80 ft apart - house & barn) that were originally powered by separate, always problematic portable gasoline generators. My work is cooling diesel and NG fired big iron prime and standby power in the harshest environments, so "robust design" is my specialty. My ideal rig would be diesel inverter versus generator, but diesel inverter pickings are slim and $$$ for only backup/occasional service. Then the Fermen MEK-803a showed up on my radar ... WOW! True, it's not an inverter, but for sure tactical, diesel and Mil-spec design checks some major boxes IMO. I pulled the trigger on one clean (enough), straight (enough) and low (enough) Hobbs and so far all systems are thumbs up for only brief unloaded power-ups to avoid wet-stacking. Just in are the AVR FNQ_R-3 fuse and holder and MOV varistor to upgrade my (older than 2009) Fermen. On the drawing board is to build a 12KW, 55 gal drum +6 x 2KW CB switched heaters hot-water load bank to verify power integrity with particular attention to brushless AVR response. I hope to scope the output and will verify fuel burn, etc. So, that's my pre-ramble.
The title begs the burning question. Yes - No - Maybe So? Mechanical is my world. I'm comfortable enough in the 'sparks and wires' world to troubleshoot and swim in the shallow end and I have all the tools AND there is that sign on my wall that does say "BE CURIOUS", but will inverter conversion require major surgery on the generator or is there a simpler 'work-around'? Also, it remains to be determined about just how good is the existing AVR (with upgrades) and especially resulting wave form factors.

Question, why would you go through an inverter if you got already a generator head installed which will do single 120, single 240 and 3P 230 at 60Hz?
Are you trying to operate a data center or your house?

 

[Mullaney]

After evaluating my emergency backup power options deep in hurricane country I concluded that diesel is king for my 10KW demand to be split between two existing 5KW manual transfer switches (about 80 ft apart - house & barn) that were originally powered by separate, always problematic portable gasoline generators. My work is cooling diesel and NG fired big iron prime and standby power in the harshest environments, so "robust design" is my specialty. My ideal rig would be diesel inverter versus generator, but diesel inverter pickings are slim and $$$ for only backup/occasional service. Then the Fermen MEK-803a showed up on my radar ... WOW! True, it's not an inverter, but for sure tactical, diesel and Mil-spec design checks some major boxes IMO. I pulled the trigger on one clean (enough), straight (enough) and low (enough) Hobbs and so far all systems are thumbs up for only brief unloaded power-ups to avoid wet-stacking. Just in are the AVR FNQ_R-3 fuse and holder and MOV varistor to upgrade my (older than 2009) Fermen. On the drawing board is to build a 12KW, 55 gal drum +6 x 2KW CB switched heaters hot-water load bank to verify power integrity with particular attention to brushless AVR response. I hope to scope the output and will verify fuel burn, etc. So, that's my pre-ramble.
The title begs the burning question. Yes - No - Maybe So? Mechanical is my world. I'm comfortable enough in the 'sparks and wires' world to troubleshoot and swim in the shallow end and I have all the tools AND there is that sign on my wall that does say "BE CURIOUS", but will inverter conversion require major surgery on the generator or is there a simpler 'work-around'? Also, it remains to be determined about just how good is the existing AVR (with upgrades) and especially resulting wave form factors.

.
I can't really talk to the wave form, but a MEP803 was built to drive electronics in a weapons system. Of course that too was built mil-spec, but always on Mobile power.

Sounds to me like you might want to download the TM's (Technical Manuals) for the machine. Reading through that might answer some questions. And, if you want to run it at 100% it will be happy...

 

[kloppk]

The AC output is pretty clean on a MEP. Here are a few oscilloscope waveforms for comparison.

Ideal 60 Hz power waveform





Typical utility power waveform (at my house)





MEP-802A power waveform at 50% Load

 

[Thermoguy]

Question, why would you go through an inverter if you got already a generator head installed which will do single 120, single 240 and 3P 230 at 60Hz?
Are you trying to operate a data center or your house?

That is very true and, of course, I am counting on 1 phase @ 120 & 240 VAC / 60 hz only. The only animals in my barn are my hunting dog and myself, because the top 900 sq ft is my office and down below are where the toys live that maintain this spread and are maintained by me in my shop. So, no data center, but for sure telephonics, telecom and computers and such that support my occupation do require clean power which, admittedly, are perfectly protected by UPS technology. Comments by you and others streaming in response providing actual sine wave of the ARV are greatly appreciated as proof of integrity of power to be expected. In my deep dive of internet including this forum this is the first time seeing exactly what I needed to see and all I had to do was ask, so thank you for that, sir.

 

[WWRD99]

After evaluating my emergency backup power options deep in hurricane country I concluded that diesel is king for my 10KW demand to be split between two existing 5KW manual transfer switches (about 80 ft apart - house & barn) that were originally powered by separate, always problematic portable gasoline generators. My work is cooling diesel and NG fired big iron prime and standby power in the harshest environments, so "robust design" is my specialty. My ideal rig would be diesel inverter versus generator, but diesel inverter pickings are slim and $$$ for only backup/occasional service. Then the Fermen MEK-803a showed up on my radar ... WOW! True, it's not an inverter, but for sure tactical, diesel and Mil-spec design checks some major boxes IMO. I pulled the trigger on one clean (enough), straight (enough) and low (enough) Hobbs and so far all systems are thumbs up for only brief unloaded power-ups to avoid wet-stacking. Just in are the AVR FNQ_R-3 fuse and holder and MOV varistor to upgrade my (older than 2009) Fermen. On the drawing board is to build a 12KW, 55 gal drum +6 x 2KW CB switched heaters hot-water load bank to verify power integrity with particular attention to brushless AVR response. I hope to scope the output and will verify fuel burn, etc. So, that's my pre-ramble.
The title begs the burning question. Yes - No - Maybe So? Mechanical is my world. I'm comfortable enough in the 'sparks and wires' world to troubleshoot and swim in the shallow end and I have all the tools AND there is that sign on my wall that does say "BE CURIOUS", but will inverter conversion require major surgery on the generator or is there a simpler 'work-around'? Also, it remains to be determined about just how good is the existing AVR (with upgrades) and especially resulting wave form factors.

I have a question...how do you plan to split the power to 2 different places...barn and home? Run 240 to a splitter and do 120 to each from there? How are you going to keep the legs balanced..ish amp wise?

 

[Thermoguy]

.
I can't really talk to the wave form, but a MEP803 was built to drive electronics in a weapons system. Of course that too was built mil-spec, but always on Mobile power.

Sounds to me like you might want to download the TM's (Technical Manuals) for the machine. Reading through that might answer some questions. And, if you want to run it at 100% it will be happy...

You are spot on about the TM's. In fact, I downloaded the TM for my 803a before I ponied up at the auction site. It is certainly a detailed

That is very true and, of course, I am counting on 1 phase @ 120 & 240 VAC / 60 hz only. The only animals in my barn are my hunting dog and myself, because the top 900 sq ft is my office and down below are where the toys live that maintain this spread and are maintained by me in my shop. So, no data center, but for sure telephonics, telecom and computers and such that support my occupation do require clean power which, admittedly, are perfectly protected by UPS technology. Comments by you and others streaming in response providing actual sine wave of the ARV are greatly appreciated as proof of integrity of power to be expected. In my deep dive of internet including this forum this is the first time seeing exactly what I needed to see and all I had to do was ask, so thank you for that, sir.

Addressing your question about why the interest in the inverter ... aside from the (now assuaged) concern about wave form quality, it is a matter of fuel consumption/economy of power production which ostensibly the inverter has an advantage over the brushless AVR approach. Actually, it begs the question: Does an inverter more effectively manage engine power output (i.e. fuel consumption) as a function of load than does the MEP's AVR? Admittedly, I do recall seeing one YouTube video where fuel consumption of an MEP- 802a was very comparable to that of a particular inverter. However, both machines were being operated at a constant, higher-than-mid-load range which is typically a sweet spot so fluctuations in power/rpm did not factor in. Regardless, and I must admit that my application is by no means 'prime power' or even designated for huge number of hours of service (hopefully) annually since it would be more emergency backup unless another H. Katrina or H. Ida shows up.

read, but your first comment about driving critical electronics makes perfect sense and is music to my virtual ears confirming my intuitive sense that the mil-spec would have so demanded. Only vets like yourself would be able to certify that to be the case. Maybe what you've stated is somewhere buried in that TM, but thank you for enlightening me about that.

 

[Ray70]

Is the barn fed from the main panel in the house or are you talking about 2 separate service entrance panels?
If the barn is a sub panel off the main house I'd assume its 240V sub, if you were feeding it 5Kw before.
If the barn is a 240 sub off the main and you were using the 2 separate transfer switches simply to be able to run the 2 5Kw generators simultaneously, but not paralleled, feeding the 803A into a single panel then through the existing breaker to the other panel will solve all your problems including balancing the generator legs.

 

[2Pbfeet]

After evaluating my emergency backup power options deep in hurricane country I concluded that diesel is king for my 10KW demand to be split between two existing 5KW manual transfer switches (about 80 ft apart - house & barn) that were originally powered by separate, always problematic portable gasoline generators. My work is cooling diesel and NG fired big iron prime and standby power in the harshest environments, so "robust design" is my specialty. My ideal rig would be diesel inverter versus generator, but diesel inverter pickings are slim and $$$ for only backup/occasional service. Then the Fermen MEK-803a showed up on my radar ... WOW! True, it's not an inverter, but for sure tactical, diesel and Mil-spec design checks some major boxes IMO. I pulled the trigger on one clean (enough), straight (enough) and low (enough) Hobbs and so far all systems are thumbs up for only brief unloaded power-ups to avoid wet-stacking. Just in are the AVR FNQ_R-3 fuse and holder and MOV varistor to upgrade my (older than 2009) Fermen. On the drawing board is to build a 12KW, 55 gal drum +6 x 2KW CB switched heaters hot-water load bank to verify power integrity with particular attention to brushless AVR response. I hope to scope the output and will verify fuel burn, etc. So, that's my pre-ramble.
The title begs the burning question. Yes - No - Maybe So? Mechanical is my world. I'm comfortable enough in the 'sparks and wires' world to troubleshoot and swim in the shallow end and I have all the tools AND there is that sign on my wall that does say "BE CURIOUS", but will inverter conversion require major surgery on the generator or is there a simpler 'work-around'? Also, it remains to be determined about just how good is the existing AVR (with upgrades) and especially resulting wave form factors.

Offshore oil rigs?

What are your anticipated loads at home? Peak kW? kWh/day? Are you thinking this is post hurricane, or off-grid?

I think that the existing '803A waveforms are about as good as it gets in my opinion.

One thing I would point out that I am sure that you know is that diesel engines do best when kept loaded, i.e. warm enough for complete combustion, generally 50% load and up. Inverter generators tend to run along at low speed for much of time before spooling up to meet a load. That leaves them cold, and prone to wet stacking and carbon build up.Some diesels, e.g. certain CAT engines have factory recommendations not to be at high idle for very long. Bottom line, your Lister Petter will need to be periodically load heavily to keep it from developing carbon deposits and the resulting issues.

So, unless you have 5-10kW loads for at least some, or much, of the time, you might be better served, and your diesel healthier, if you ran the output of the '803 into a 10kW battery charger, with enough batteries to take in 20-30kWh of load in a couple of hours, and then ran your barn and house off of the battery bank. There are off the shelf solutions from Panasonic, Enphase, and others, as well as lots of DIY versions from lead acid batteries or used EV automotive battery packs.

So, while anything is doable, no, I would not go down the inverter conversion route on an '803A. If you really want a diesel inverter, I'd build it from scratch.

All the best,

2Pbfeet

 

[Guyfang]

The 400 hertz model of this machine drives Radar and Missile Systems. The 60 hertz model drives ANYTHING. From a skill saw to satellite commo systems. Not too shabby for a little diesel driven gen set.

 

[Thermoguy]

I have a question...how do you plan to split the power to 2 different places...barn and home? Run 240 to a splitter and do 120 to each from there? How are you going to keep the legs balanced..ish amp wise?

Good question. My plan is to wire a 'double take off' 6/3 AWG from L1 and L3 plus neutrals.
The run to the barn transfer switch is only about 6 feet which will terminate at the 30A twist male plug (L1a - L3a - Na).
The barn transfer switch has:
2 @ 120 VAC circuits (L1) for dedicated outlets
2 @ 120 VAC circuits (L3) for dedicated lights
1 (2 combined circuits) @ 240 VAC combined L1+L3 for 240 VAC submerged well pump controlled by Variable Frequency Drive controller
NOTE: The 'Freq Drive' always provides 'soft start' on the well pump AND constant line pressure target is the control criteria, all mitigates power surges.

The run to the house transfer switch is about 80 feet which will terminate at the 30A twist male plug (L1b - L3b - Nb).
The residence transfer switch has:
3 @ 120 VAC circuits (L1) for dedicated outlets for dedicated outlets, lights + 1 refrigerator
3 @ 120 VAC circuits (L3) for dedicated lights for dedicated outlets, lights + 1 refrigerator

 

[Thermoguy]

Offshore oil rigs?

What are your anticipated loads at home? Peak kW? kWh/day? Are you thinking this is post hurricane, or off-grid?

I think that the existing '803A waveforms are about as good as it gets in my opinion.

One thing I would point out that I am sure that you know is that diesel engines do best when kept loaded, i.e. warm enough for complete combustion, generally 50% load and up. Inverter generators tend to run along at low speed for much of time before spooling up to meet a load. That leaves them cold, and prone to wet stacking and carbon build up. Some diesels, e.g. certain CAT engines have factory recommendations not to be at high idle for very long. Bottom line, your Lister Petter will need to be periodically load heavily to keep it from developing carbon deposits and the resulting issues.

So, unless you have 5-10kW loads for at least some, or much, of the time, you might be better served, and your diesel healthier, if you ran the output of the '803 into a 10kW battery charger, with enough batteries to take in 20-30kWh of load in a couple of hours, and then ran your barn and house off of the battery bank. There are off the shelf solutions from Panasonic, Enphase, and others, as well as lots of DIY versions from lead acid batteries or used EV automotive battery packs.

So, while anything is doable, no, I would not go down the inverter conversion route on an '803A. If you really want a diesel inverter, I'd build it from scratch.

All the best,

2Pbfeet

Jack-up rigs GOM, North Sea, Aramco and production mostly GOM - Absolutely the best of the best to work with - an honor and privilege. Also, land-based prime power, etc. including waste heat recovery - tropical and sub-tropical - all time zones. Who needs sleep?

New information: Barn and residence have separate 200 amp services. Of course that will have no bearing on what MEP-803a sees. I detailed each transfer switch in previous response which likely combine to distribute loads, although I have never had luxury of doing a load profile study. The well pump is always doing something as directed by the freq-drive along with all the other very distributed loads over outlets, lighting and refrigerators.

I am considering purchasing just such a monitoring/recording device for this installation. Any recommendations would be greatly appreciated by me and the newest addition to our family - Genny.

 

[2Pbfeet]

Jack-up rigs GOM, North Sea, Aramco and production mostly GOM - Absolutely the best of the best to work with - an honor and privilege. Also, land-based prime power, etc. including waste heat recovery - tropical and sub-tropical - all time zones. Who needs sleep?

New information: Barn and residence have separate 200 amp services. Of course that will have no bearing on what MEP-803a sees. I detailed each transfer switch in previous response which likely combine to distribute loads, although I have never had luxury of doing a load profile study. The well pump is always doing something as directed by the freq-drive along with all the other very distributed loads over outlets, lighting and refrigerators.

I am considering purchasing just such a monitoring/recording device for this installation. Any recommendations would be greatly appreciated by me and the newest addition to our family - Genny.

Sounds like fun.

The VFD pump controller will make life easier for your generator. As a general rule, I would suggest line reactors on the 3 phase side (if it is 3 phase), and some extra toroids or an EMI snubber on the input side. (E.g. something like this one 20A@240V)

https://www.amazon.com/Uxcell-CW4L2-20A-S-Noise-Suppressor-Filter/dp/B016EJ5DU2

The VFD controllers are great, but they can put a fair amount of electrical noise on the system. I once saw a square toroid made out of black iron pipe elbows, nipples and unions. Apparently it worked a treat.

I think a pair of ammeters to cover each leg, or combined amp+volt meters might do everything you need. If you really want recording, they do make data loggers. Personally, I have not found inexpensive ones, especially not loggers that capture enough data to find sub Hz transients, but I don't know why you want the logging and thus what data rate you want. @kloppk makes a remote start kit that I believe has some data logging (Every 10seconds?).

All the best,

2Pbfeet

 

[DieselAddict]

I don’t think converting it to an inverter style generator is practical. You can add an external hybrid inverter into the mix to give you more flexibility and fuel efficiency.

Since I put in my system which has Solar with battery storage, I run the generator far less for outages than I used to.

 

[Ray70]

It sounds like you are essentially only trying to power a small number of dedicated outlets, fridge, some lights and the well pump.
This is almost no load at all for that 803!
Even the well pump is nothing. The 803 will run your entire house and barn, and it will be much happier over time if you run it at a moderate load.
Long runs at very light loads will eventually lead to wet stacking, a buildup of carbon in the muffler.