re-wiring my MEP-004a for different voltages, including single phase

[1800 Diesel]

The wattage rating should be 10 watts or more. The resistance rating of 38 ohm will provide 100% accurate meter readings and trip setpoints. A slightly higher resistance value will result in slightly higher meter readings, and slightly lower trip setpoint. The 50 ohm resistors I used resulted in the meters reading a few percent too high, and a trip setpoint of 18kw (slightly too low). Any resistance between 38-50 ohm will be fine...we're only talking about a few percent, and the meters usually are less accurate than that anyway. I would choose the cheapest 10+ watt resistor between 37-50 ohm and go with that.

Copy--I'll go with the 39 ohm/25 watt, unless I can locate one in the 15-20 watt range. Thanks for the reply & looking forward to finishing the job....now if I can just get moving on our 38 KW load cell...

Thanks again & don't forget to let us know if you make it to the FL panhandle or anywhere close to New Orleans...steak or cajun seafood dinner on me...

 

[towrecker]

Copy--I'll go with the 39 ohm/25 watt, unless I can locate one in the 15-20 watt range. Thanks for the reply & looking forward to finishing the job....now if I can just get moving on our 38 KW load cell...

Thanks again & don't forget to let us know if you make it to the FL panhandle or anywhere close to New Orleans...steak or cajun seafood dinner on me...

I bet he could take a road trip from coast to coast , and get 3 free meals a day from the ones of us he has helped , he is like me , would help anyone that appreciates it , I can fix about anything , but the mep-004a was foreign to me , and if not for sewerzuk , I would have never had anything more than a yard ornament I also found some 38.3 ohms , 50 watt resistors that have a design that will be not only bullet proof , but so easy to install , I know this was months ago , and you have , I am sure already completed yours , but here is a linky to them @ $5.59 each through mouser http://www.mouser.com/Search/Produc...0FC02virtualkey61300000virtualkey71-RH50-38.3 Have Great Day

 

[sewerzuk]

Just completed a single phase conversion on an -006a, and I shot some video of the process.
The conversion is similar to the -004/-005 one, but quicker and less difficult due to better access to the voltage reconnection board.
I will edit and upload the video soon; sometime in the coming few weeks.

 

[Hammer]

Have you thought about doing a LARGE selector switch to switch between single and three phase, like the -002 does?
I would really like to have a 15k for the house setup (I already have the -002a that works great, but have to watch the loads), and also use it for three phase stuff in the shop without having a huge rewiring hassle.

Btw, thanks for you efforts and not so trivial adventures Sewerzuk!

 

[Harleyd315]

I have an 005 that a friend wants to use at his shop. He has 120/240 3 phase Delta service. Has a 120/240 Delta configuration ever been done on one of these generators? Thanks

 

[sewerzuk]

I have an 005 that a friend wants to use at his shop. He has 120/240 3 phase Delta service. Has a 120/240 Delta configuration ever been done on one of these generators? Thanks

I have never done a 120/240 delta re-wire on one of these...but I know it is possible! It would require removal of the voltage reconnection board (or customization of the plate). The rest of the generator systems should have no problem with this configuration, as it is still 120v per phase.

 

[PeterD]

If that 120/240 delta is using a tap on one of the delta phases to get a neutral (for the 120) you will have problems balancing the load on the generator set. The reason the power company can do this is because they can tap one phase for one customer, another phase for a second customer and the third phase for a third customer, and so on. In the end things balance out. But if you have one customer then balance will be difficult if the 120/240 single phase loads are significant.

As Sewerzuk says, there is no reason the generator won't do this, as long as you are willing to go to the trouble of creating a new reconnection board.

 

[dependable]

Have you thought about doing a LARGE selector switch to switch between single and three phase, like the -002 does?
I would really like to have a 15k for the house setup (I already have the -002a that works great, but have to watch the loads), and also use it for three phase stuff in the shop without having a huge rewiring hassle.

Btw, thanks for you efforts and not so trivial adventures Sewerzuk!

I converted a MEP-018 reconnection switch to switch phases on my 1031. It would work on any similar sized 12 lead generator, I think. link below shows project so far.
#15

Editing to note that the 120/240 off the MEP-018 switch is in Delta configuration.

 

[CarboneroHokie]

Has anyone had any issues with the frequency on one leg being different than on the second leg after the 3 phase to single phase conversion? I can't say for sure if this was a pre-existing issue before the conversion, because I don't recall taking frequency measurements before the conversion. My Hertz meter doesn't work, so all my measurements are taken via a digital multi-meter. I was able to make the conversion earlier this summer thanks to sewerzuk and his detailed instructions, a big thank you for the information you provided!!!!

Right now, when I crank up the generator I get aprox. 45 hz on one leg, and about 360 hz on the other leg with the generator at idle. Once I have adjusted the RPMs up to where I read 120 volts and 60 hz on one leg, the other leg reads 120 volts and 180 hz. If I remember correctly when we used it at the beginning of summer, once the generator was under load, this issue resolved itself, with both legs reading 60 hz. However this concerns me and was wondering if anyone had run into this issue, knows what I could check, or what the problem might be.

Thanks!

 

[steelypip]

Your Hz meter is overly sensitive and is picking up harmonics from the gen head. If RPM is constant, then frequency is constant, and will be the same for all the windings.

 

[Isaac-1]

Like he says many cheaper multimeters (and some expensive ones) have this problem, My suggestion is to either get a good Fluke meter, or a cheap sub $20 Kill-a-Watt P4400 as they seem to do good on reading generator frequency without distortion.

 

[aczlan]

steelypip and Isaac-1 nailed it. Hertz on the output is a function of how fast the generator head is spinning and it will be the same on all legs of the same genset (unless someone did something REALLY weird with the windings when they made the generator head). Converting from 3 phase to single phase will have no effect on how many hertz the genset is putting out.

Aaron Z

 

[CarboneroHokie]

Thanks guys! That makes me feel a lot better! And now that you pointed it out, I have been taking the measurements with the same multi-meter, a cheap one.

 

[sewerzuk]

x4 what those guys said!

Frequency physically cannot differ from phase to phase (with your generator head, anyway).

My "cheap" frequency meter will bounce all over the place if the generator is not producing power (detecting noise) but locks into a steady reading once the field is flashed. Was your generator producing 120/240 when you were taking those readings?

 

[CarboneroHokie]

Yes, I had adjusted the voltage, and was getting a steady 120/240 while I was seeing 60 hz on one leg and 360 hz on the other. Field was flashed, but no load on the generator.

 

[hamrepairguy]

The conversion for the -005 should be exactly the same as the -004; the schematics I used for the -004 cover both models.

This de-rating thing can be a complicated question. We have a few things to worry about:
1. The current through individual generator windings. I have not yet taken current readings and compared them at full load 3 phase vs single phase on each winding. I do intend to do this. I don't think this is an issue, as the zigzag configuration is considered "balanced" (although it looks a little strange on paper).
Edit: I have tested all 12 leads under full load, and the current was balanced to less than 1A between all leads
2. The cable size from the reconnection board to the breaker, the breaker itself, and the cable going to the load terminals. The breaker is not an issue. It can handle the extra current. The cable size is too small for the higher single phase current through L1 and L3. It should be up-sized. If you don't upsize it, I seriously doubt anything bad will happen...but you may experience a slight voltage drop across those lines at full load and/or some warming. I intend to put some 4 AWG cable on my -004.
3. The overload trip setpoint on the generator. I have not yet tried to raise the trip setpoints for the overloads (planned for this Sunday night). They still trip at their 3 phase setpoints. This is roughly 55A for the -004 (mine trip at about 60A), and 110A for the -005. At the new higher voltage, this gets you 14kW for the -004, and 27kW for the -005. This means that, at the new higher 120/240 voltage, the sets trip at just below their full rating. However...the set won't trip for a full 8 minutes of overload. That means that, on your -005, you can pull 27kW all day long and for a few minutes at a time put even more (40kW is possible on a good-running -005, 23kW on on -004).

The bottom line is, you can do the single phase mode I show in my video, move the leads on the reconnection board as I describe in post # 40, and put your generator to work single phase. It will work just fine this way, especially if you intend to load it to 50-80% of its capacity with only occasional 100% transients.

I'll have another video up 2 weeks from now describing/detailing the ENTIRE conversion, not just the zigzag mod shown in the first video. Should be fairly easy for the average wrench-turner to accomplish.
Edit: New video is at the end of post #1

are these mods the same for a 60hz mep 006a

 

[sewerzuk]

are these mods the same for a 60hz mep 006a

It is very similar, but not exactly the same.
The actual job of re-wiring the reconnection board is quite a bit easier, as there is more room to work. I am working on a video from an -006 conversion that I did...just haven't had the time to edit and upload it yet.

 

[hamrepairguy]

It is very similar, but not exactly the same.
The actual job of re-wiring the reconnection board is quite a bit easier, as there is more room to work. I am working on a video from an -006 conversion that I did...just haven't had the time to edit and upload it yet.

Thank you for the response. I look forward to seeing the video so I can convert mine over.

 

[hamrepairguy]

Thank you for the response. I look forward to seeing the video so I can convert mine over.

A kraus and naimer rotary switch would work well for the high current switching. And ohmite rotary switches for the low current switching

 

[smurph]

sewerzuk,

I picked up 3 mobile (M200A) MEP-005As at auction and I'm in the process of getting them all running. 2 are up and running at this point. I did the single phase mod to one of them and I'm tickled pink! Thanks for the videos and the posts!

I really liked your videos on prepping these things to bring them back to life. All common sense stuff that is easily forgotten in haste. So it was really nice to have a one stop place to get all of the info needed.

So far, one needs a Hz. gauge and/or transducer, the other one needs a power percent meter (leaked and corroded inside). Other than that, these two fired up in short order. Then there is #3... fuel problems. It is the one that looks the newest, has 17 hrs on the meter, shiny fittings, engine paint that you could eat off of, battery box that looks to have NEVER had batteries in it with shiny new cables and connectors. So looks are not everything!

Steve