rewiring MEP004 for single phase

[retiredtoy]

I'm only 4 weeks old as far as being an SS member, but I really enjoy reading about all the experiences that I have already been there and done that. Guess I'm too old.
About the 15 KW gen. One thing to think of it that the 15kw rating is with using all three legs. When you use two legs, it knocks down your power output a third. And honestly, when I went through Missile Electronics (Guidance and Controls system mechanic on the Bomarc Missile) I think you multiplied the output times .707 for the actual RMS value. I'ts been a while since 1960 and I might not have that right. I do have one thing right though: There are inverters that are getting very cheap nodays that are designed to take the 3-phase power, rectify it to DC. then change it back to any voltage, frequency, or phase you would want. By using the inverter, you don't have to worry about changing the generator. Well I hate to waste all that I wrote, but I just thought of one other thing you would need with an inverter. A transformer so you could get the common for the two 120 volt circuits. The main advantage of the inverter is to obtain the full 15KW power out of your generator.

 

[Isaac-1]

Fred, one more thing to remember, depending on your loads, how you plan to connect your generator, etc. You might be able to get that 1/3 output back as an separate 120V only line. Perhaps you have a well pump that could run off 5KW's of 120V AC, or maybe an RV with a 30-50 amp 120V only connection, Or get creative on your transfer switch wiring (insert words of caution, consult a professional that KNOWS what they are doing, etc). Or just run extension cords from this spare line connection.

Ike

 

[FREDS]

I plan to. I have some ideas on some stuff I can run off of the extra leg.

And I can probably use that 5 kw somewhere.

Whatever I do, this will be a step up.

Right now, my backup generator is the auxiliary coil on a Miller stick welder. Runs a couple of lights, and keeps the heat on.

Well pump pretty much kills it. Big time brownout, and not too good for the well pump either.

Good welder, not so good as a generator.

 

[Isaac-1]

Fred, that sounds like the diesel powered Miller Big-D2 out at my families farm, 200A 100% duty cycle for welding, but only 2.5 KVA on the AC generator side at 120V (could be rewired for 240).

Ike

 

[FREDS]

Similar. The MEP 004 will be a touch better.

 

[MidnightDuramax]

I am looking for a manual for my mep 004 and would also like some more info on rewiring. If anyone could supply some kind of diagram that would be great.

 

[panzerjunky]

MEP400A 3 phase to single conversion

good point m16, but I'm also willing to bet that you don't use your tractors like that every single time you get them out too. The problem crops up a lot more because of prolonged usage like that...if you have a 60 KW generator that is running your 1200 sq/ft home, it's NEVER going to see enough load at any time to ever burn off the build-up that is present from the previous lightly loaded run. Whereas your tractors will get a good work-out, whether it be plowing or mowing or whatever, probably the next time you fire them up, if not the next time, very shortly after you had run them that lightly loaded.

Hey Speddmon and fellas
Thanks for the informative thread on genys I must state that i am absolutly no expert on gen sets and only am operating off what i have learned here and from gen dealers.
On wet stacking
I talked to a cat rep who is installing a Backup gen at a hospital that is being built in town here I explained the use to him and he said that with the limited intermittent use the wet stacking most likely won't be an issue. i called a mfg / Distributor of load banks ready to buy one they talked me out of it said that with the low again intermittent use just once a year when you do maint have a gen shop put a load bank on her and just blow her out Now that was based on intermittent use .
My MEP400A was conv to single phase ( not by me ) by removing the copper bar from the back of the board cutting off one of the holes (shortened it by one hole) then bolted the bar back on the top on the neg 10 and 11 lug and then jumper either with a newly made piece of copper with 2 holes or a jumper wire ( this is how mine was done) between lug 8 and 6 now you have single phase power to go to 3 phase move the jumper to lug 11 and 12 that simple. For higher voltage move the whole board up I think it is one set of lugs until the arrows line up with the high voltage I think 240 480 and move the copper bar down one row so it is on lugs 4 5 6 then use the jumper wire to complete the row.
This is how my MEP400A is set up and it works we tested with a multi meter through all HZ and voltages and they read correctly. The fella who did this has the same geny but with the sound jacket he powers his house with this and solar he has ran it this way for the last 3 to 4 years with abbsolutly no problems. He did say that there is 2 ways the MEP 400A is wired depending on Mfg so if there are other changes to the wiring from the gen head I am not sure but i was told usually not
My question to you gents who know a lot more about this than i ever will does this sound like a viable solution. as it is a lot better than replacing the board if some of you more knowledgeable fellas want I can get a wiring Dia. and complete instructions from him and e-mail them to you for review to see if this works or we made a bomb I would just take photos but for some reason i cant post pic on this site thats for another forum.
Any thoughts
Jerry

 

[FREDS]

Hey
This was my thread initilly.

I have scoured the internet for any informtion about this conversion. It doesn't exist.

So if you can post or send instructions and pictures I will get them posetd here.

Great post, thanks

 

[panzerjunky]

I will do what I can as I have to go see the guy who I got my genny from for other business maybe I can get him to write up a step by step and I will post some of the pics of mine then the guys here on the site who are in the know ( you know who you are) can review the info see if it is sound and not dangerous in any way and we will be good to go. I do know the guy i got this from sells a ton of the 004 and 005 gen sets in this area as he buys them 3 and 4 at a time and he does them all this way so I am looking forward to a review myself to see if my little genny is good to go.
Take care
Jerry

 

[joshgar8]

Panzerjunky, I am in the same boat with many other guys needing the info you are trying to get. If you could get a detailed step by step to convert to 120v-240v single phase, that would be great. My generator is currently at a major gen shop right now getting some things worked out on the voltage regulator. After he gets that taken care of, and if we get a set of instructions I will run those by him to get his opinion. He does have a load bank to test so we could see exactly what it puts out after the conversion.

 

[Speddmon]

Hey Speddmon and fellas
Thanks for the informative thread on genys I must state that i am absolutly no expert on gen sets and only am operating off what i have learned here and from gen dealers.
On wet stacking
I talked to a cat rep who is installing a Backup gen at a hospital that is being built in town here I explained the use to him and he said that with the limited intermittent use the wet stacking most likely won't be an issue. i called a mfg / Distributor of load banks ready to buy one they talked me out of it said that with the low again intermittent use just once a year when you do maint have a gen shop put a load bank on her and just blow her out Now that was based on intermittent use .
My MEP400A was conv to single phase ( not by me ) by removing the copper bar from the back of the board cutting off one of the holes (shortened it by one hole) then bolted the bar back on the top on the neg 10 and 11 lug and then jumper either with a newly made piece of copper with 2 holes or a jumper wire ( this is how mine was done) between lug 8 and 6 now you have single phase power to go to 3 phase move the jumper to lug 11 and 12 that simple. For higher voltage move the whole board up I think it is one set of lugs until the arrows line up with the high voltage I think 240 480 and move the copper bar down one row so it is on lugs 4 5 6 then use the jumper wire to complete the row.
This is how my MEP400A is set up and it works we tested with a multi meter through all HZ and voltages and they read correctly. The fella who did this has the same geny but with the sound jacket he powers his house with this and solar he has ran it this way for the last 3 to 4 years with abbsolutly no problems. He did say that there is 2 ways the MEP 400A is wired depending on Mfg so if there are other changes to the wiring from the gen head I am not sure but i was told usually not
My question to you gents who know a lot more about this than i ever will does this sound like a viable solution. as it is a lot better than replacing the board if some of you more knowledgeable fellas want I can get a wiring Dia. and complete instructions from him and e-mail them to you for review to see if this works or we made a bomb I would just take photos but for some reason i cant post pic on this site thats for another forum.
Any thoughts
Jerry

Jerry,

First off, the load bank manufacturer/distributor you talked to pretty much hit the nail on the head about wetstacking. If you at least run the generator at load every now and then to get it to operating temperature and allow it to burn off the deposits left behind it will be fine. The CAT rep doesn't have a clue, as it's the intermittent operating over an extended period that causes the problem. It needs to be brought up to temp occasionally to keep it cleaned out.

I have read and re-read the the post about the connections you have in your generator. I can see what is going on when you have it set for low voltage, you are basically creating an open delta set-up, but you have a third leg out there floating around not tied to anything. I do have a few questions for you though, I would like to look at this a little more in depth. When you have it set for low voltage and you have the jumpers installed for the 120/240 single phase operation. Which output lugs are you getting the 240 volts from? L1 & L2, or L1 & L3, or L2 & L3?

Also, the explanation you gave for switching it to high voltage does not make any sense to me. If you are putting a bar across terminals 4, 5 and 6...that is strictly for a low voltage connection, as with them tied together you are basically putting the coils of the generator in a parallel connection. For high voltage you have to have them hooked up in series with each other so the generated voltage is additive. Also, there would be no advantage to having the set hooked up to high voltage, unless you intended to use it for 3 phase WYE which will only give you 416 volts and not 480. If you reconnected the output for high voltage single phase, you "should" get single phase 480 volts, but to the average homeowner, what is the good in that? Even in industry, we don't use 480 volts single phase very often.

As to the metering and regulation side of it, by re-connecting it for low voltage single phase as you described, I can see only one potential problem, and that is with the load metering. Your % load meter will probably not be reading accurately, and you will have a severely unbalanced load on the generator due to that one phase just floating around in space and not being used. Doing it this way will drastically de-rate your capacity as well. I'm guessing at least 1/3 or even closer to 1/2 the rated output. That being the case, it will be even more important to hook the set up to a load bank at least once a year and reconfiqure it for 3 phase again and fully load it to get it up to temp and burn off any deposits. Because you are never going to be able to put enough load on it in single phase operation to get the engine hot enough without damaging something in the generator.

 

[panzerjunky]

Jerry,

First off, the load bank manufacturer/distributor you talked to pretty much hit the nail on the head about wetstacking. If you at least run the generator at load every now and then to get it to operating temperature and allow it to burn off the deposits left behind it will be fine. The CAT rep doesn't have a clue, as it's the intermittent operating over an extended period that causes the problem. It needs to be brought up to temp occasionally to keep it cleaned out.

I have read and re-read the the post about the connections you have in your generator. I can see what is going on when you have it set for low voltage, you are basically creating an open delta set-up, but you have a third leg out there floating around not tied to anything. I do have a few questions for you though, I would like to look at this a little more in depth. When you have it set for low voltage and you have the jumpers installed for the 120/240 single phase operation. Which output lugs are you getting the 240 volts from? L1 & L2, or L1 & L3, or L2 & L3?

Also, the explanation you gave for switching it to high voltage does not make any sense to me. If you are putting a bar across terminals 4, 5 and 6...that is strictly for a low voltage connection, as with them tied together you are basically putting the coils of the generator in a parallel connection. For high voltage you have to have them hooked up in series with each other so the generated voltage is additive. Also, there would be no advantage to having the set hooked up to high voltage, unless you intended to use it for 3 phase WYE which will only give you 416 volts and not 480. If you reconnected the output for high voltage single phase, you "should" get single phase 480 volts, but to the average homeowner, what is the good in that? Even in industry, we don't use 480 volts single phase very often.

As to the metering and regulation side of it, by re-connecting it for low voltage single phase as you described, I can see only one potential problem, and that is with the load metering. Your % load meter will probably not be reading accurately, and you will have a severely unbalanced load on the generator due to that one phase just floating around in space and not being used. Doing it this way will drastically de-rate your capacity as well. I'm guessing at least 1/3 or even closer to 1/2 the rated output. That being the case, it will be even more important to hook the set up to a load bank at least once a year and reconfiqure it for 3 phase again and fully load it to get it up to temp and burn off any deposits. Because you are never going to be able to put enough load on it in single phase operation to get the engine hot enough without damaging something in the generator.

Great sppeddmon
This is what I wanted Now I have a laundry list so to speak of potential issues for said conversion now I have an appointment with the guys at Hawthorne equipment this coming Tue providing I have the cash available for a couple hours at $110 per they will check out the conv as well as load bank it to check output ect. I will show them all the Posts from this thread If that is ok with you guys.
That way we will have a diffinitive hopefully set of instructions to reconfigure these genny's without making a grenade out of them. The conv may not be 100% efficient but it will be safe that is my goal. This will take a week or so .
Thanks Jerry

 

[Isaac-1]

Jerry, I see your in the San Diego area, you might want to try calling Hardy Diesel, they sell mostly small to mid size import generators, as well as solar power equipment for off grid use. I have bought a couple of accessory items from them and they seem good to deal with, a small operation, but that is not always a bad thing. Check out there web page
hardydiesel.com, I know they also dealt in used generators, but don't seem to do that much anymore.

Ike

 

[papercu]

There is a power unit being sold on MV list that includes a 7.5KVA transformer, I'm assuming this is would be in-between the generator and the load. You might get a used transformer to match your input/output load easier/cheaper than rewiring the generator. Wayne

 

[PeterD]

Here is the diagram to do the conversion. However, the MEP-004A has a ten lead head, where the three common wires are connected together. Where they are connected is something I don't know, it may be at the stator itself, or the patch board, I'm not sure.

Zig-Zag connection generally will not allow full power, but IMHO the MEP-004A is so over engineered I suspect you can get full power from it.

 

[Speddmon]

Here is the diagram to do the conversion. However, the MEP-004A has a ten lead head, where the three common wires are connected together. Where they are connected is something I don't know, it may be at the stator itself, or the patch board, I'm not sure.

Zig-Zag connection generally will not allow full power, but IMHO the MEP-004A is so over engineered I suspect you can get full power from it.

The TM shows it as being a 12 lead head. Generator heads like motors are pretty standard, and I've never seen a 10 lead motor. 3, 6, 9 or 12 lead is what you usually get. Not to say that they are not out there, but just not very common.

 

[panzerjunky]

The TM shows it as being a 12 lead head. Generator heads like motors are pretty standard, and I've never seen a 10 lead motor. 3, 6, 9 or 12 lead is what you usually get. Not to say that they are not out there, but just not very common.

Yes I am by No means an expert but I am sure the MEP004A is a 12 lead head
Thanks Jerry

 

[PeterD]

Absolutely correct, I don't know where I got the ten lead reference. And that being the case, a conversion to single phase may well be much easier. IIRC there are several other references to the conversions on the Internet.

The 'magic' place to connect to is TB6, where all 12 leads go. This is after the current transformers for the power meter, which may affect its accuracy, but that's a minor point in the scope of things...

 

[MidnightDuramax]

This may sound a little crazy but I have been working in my generator and have a few problems. Hopefully they are simple ones I am just over looking. As of right now I don't seem to be getting any electric out of it. Is there a few things to check first or common things that cause this? The other thing is that the start switch activates the fuel pump but not the starter motor. I am guessing it could be the starter relay. Any other suggestions would be great and if anyone knows where the starter relay is located?

Thanks

 

[MidnightDuramax]

This may sound a little crazy but I have been working in my generator and have a few problems. Hopefully they are simple ones I am just over looking. As of right now I don't seem to be getting any electric out of it. Is there a few things to check first or common things that cause this? The other thing is that the start switch activates the fuel pump but not the starter motor. I am guessing it could be the starter relay. Any other suggestions would be great and if anyone knows where the starter relay is located?

Thanks