S788 shortened shelter meets MEP 017a

[04mustang]

Hi everyone,
I recently purchased a S-788 shortened shelter from GL. When I got it it was missing the MEP-903 generator that it should have had in the tunnel.
My plans are to mount this shelter on a M105 frame I have and repower it with a smaller MEP-017a generator to be able to run the A/C unit, heater, and lights, and maybe a few other small things.
I am aware of the issues with the old gas generators being loud and fuel consumption being bad. This is just my short term plan to be able to power everything up and make sure it all works like it should.
My issues are that I want to be able to make sure I wont blow something up in connecting it the way I think I can. I am planning to just wire the generator to the shelter using the same L0, L1, L2, L3 wires that the original MEP-903 would have been connected to. Does anyone see anything wrong in that logic?
The A/C / Heater unit in this shelter is listed as 3.9 Kw, the MEP-017a is rated at 5kW. The original MEP-903 would have been 10kW.

Thoughts?

 

[Guyfang]

Oh no!!!!!!!!!! An Ordnance guy!!!!!!!!!!!!! Lord save us. No, not everyone can be born lucky, and be an Engineer. You got to start thinking about a branch transfer. Just kidding partner. Well, mostly anyway.

I don't see a problem. The shelter originally held many other things that ate lots of power. You need to add up the requirements that you now have in the shelter, lights, heater, air con and the like. If they do not exceed 5 KW, then you should be good to go.

Take care and don't forget to ground the thing!
Oh, do you still have the engine cover? Its not good for old betsey, (MEP-017A) to run without the cover. She will/could over heat without it. Do you have the TM's for her?

 

[04mustang]

Hi! Oddly enough I was a combat engineer prior to being commissioned as an ordnance officer. And I have an engineering degree. Just not electrical, lol.
I do still have the cover. And I keep it covered when not in use. I'm still going through the generator and getting it ready for use. I just bought it yesterday.

 

[jamboly]

You should be okay using the same L0, L1 etc connections. As others mentioned, make sure you ground the thing and check the total amount of power you plan to draw in the shelter to make sure the MEP-017A will handle the load, especially with the heater on. I have several MEP-017As and can attest to the fact that they are noisey.

 

[04mustang]

Thanks for the info!
I went back and looked over the wires on the shelter end last night briefly. I have 5 wires actually, Lo, L1, L2, L3 and another with a green tape on it (I would assume the ground). I also have 2 black wires heavy gauge wires that were connected to the MEP903 for remote operation, I think. That would make sense being it was housed in a tunnel and you have the control panel for it on the other side of the shelter in that tunnel.
My thoughts are to not connect those 2 wires to the MEP017a just because from what I gather with how you have to start the thing with the governor that remote operation probably isn't a good idea.

Is it same to assume that I would wire the ground from the shelter to the ground post on the generator frame?

 

[Guyfang]

Thanks for the info!
I went back and looked over the wires on the shelter end last night briefly. I have 5 wires actually, Lo, L1, L2, L3 and another with a green tape on it (I would assume the ground). I also have 2 black wires heavy gauge wires that were connected to the MEP903 for remote operation, I think. That would make sense being it was housed in a tunnel and you have the control panel for it on the other side of the shelter in that tunnel.
My thoughts are to not connect those 2 wires to the MEP017a just because from what I gather with how you have to start the thing with the governor that remote operation probably isn't a good idea.

Is it same to assume that I would wire the ground from the shelter to the ground post on the generator frame?

Morning!

So, the truth comes out!! Its good that you were a Combat Engineer before. Now we can use words with more letters then three! Just kidding. Ord. guys made my life tough when I was in a Maintenance unit. I wore a flack vest every day at work.

Yes, attach the van ground, to the gen set ground wire/terminal/ground rod. Reason being, if there was a short on the shelter, and it was not bonded to the same ground as the sen set, and you had your hands on both of them, you would become the ground path.

Do not connect the two black wires. You can rig up a remote gen start circuit, but its a tad more complicated as the 017A is not compatible to the van at this time. You could change that later if you wanted to.

 

[04mustang]

Well.........I really should read more before I jump.
The MEP-903C that would have come in this shelter is a single phase 3 wire generator.

Which means that using my MEP-017a that I bought just got more complicated.

 

[04mustang]

Can someone explain to me how the mep 903 is a single phase 3 wire generator but has connections for L1, L2, L3, neutural and a ground?
And how would I set any other generator up to work instead of the 903 since I can't find one below $3000

 

[quickfarms]

Can someone explain to me how the mep 903 is a single phase 3 wire generator but has connections for L1, L2, L3, neutural and a ground?
And how would I set any other generator up to work instead of the 903 since I can't find one below $3000

I will sell mine for less than that

 

[04mustang]

I have attached labels for the wiring of this shelter to the generator that it had at one point.
They are:
L0(neutral)-white
L1-Black
L2-Red
L3-Blue
Ground-Green

Now I understand that the MEP-903 is a single phase 3 wire generator, which means that there should not be a L3.
Combine this information with the fact that A/C and heater unit data plate clearly reads that it is 3 phase 120/208.
I am very confident that the generator should be wired as a 3 phase 120/208. Does this make sense?

 

[04mustang]

So after a little more research I think I have it figured out. But this how the original MEP-903 was wired into the shelter.
L3-Blue wire to L3 post but bridged to connect with L0 post
L2-Red wire to L2 post
L1-Black wire to L1 post
L0 (neutral) to L0 post but bridged to connect to L3 post
Green Ground Wire to ground post


So now is the trick how to do this with the MEP-017a if it can be done?

 

[quickfarms]

This shows the posts on the back of the Mep 903



This is the unit with my homemade control

 

[jamboly]

From what I could find in a quick search, the MEP903 output is 120/240 three (four if you count ground) wire single phase (I could not tell the labeling on the photos that were posted). That is the same type of power you have going to your house. There used to be some postings on the internet on how to get 120/240 single phase out of an MEP017A, but if I remember, it involved tearing into the generator to find a neutral winding. Do a search for MEP017a and house power, you might find it.
The MEP002/3 were designed to provide switch selectable 120/240 single phase three wire, the extra terminal posts on them are because they are also switch selectable for three phase.
From reading some of your posts, you need to be careful not to start confusing the number of phases and wires. There are such things as single phase four wire, etc.
I would highly recommend you keep looking for a cheap MEP903. A lot of them are starting to be auctioned off.

 

[quickfarms]

I would highly recommend you keep looking for a cheap MEP903. A lot of them are starting to be auctioned off.

I have not seen one auctioned off in a few years

 

[04mustang]

Thank you all for the information.
I have added photos of part of the wiring schematic for the MEP-903 as well as how the wires are labeled in the shelter.
I also have photos of the power entrance/distribution box (bolted to the front/roof of the tunnel) and the inverter? box (bolted to the floor of the tunnel)

Based on what I am seeing, and please tell me if you see something I don't, ....
I could use a standard household generator with a 4 pin twist lock plug to test the power out in the shelter. I just need to connect the currently lugged wires from the shelter to a 4 pin twist lock male plug. I do not see a need to connect any batteries to this setup.
Originally This shelter used the battery power from the hmmwv and the fuel tank from the hmmwv to power the MEP-903. Which is why all the ones that were surplused do not have fuel tank or battery setup.

 

[jamboly]

Yes, that should work. The trick is to make sure you get the right wires from the twist lock plug to the right lugs (L0,L1 etc) on the shelter. You might PM quickfarms to tell you which lugs on his generator provide which voltages. Normally in a single phase set up, you will have 240v across two of the terminals and 120v from each of those two terminals to the other. Once you have that I would recommend that you consult with a local electrician (preferable one that does a lot of home standby generators) to make sure you wire it up right.

 

[quickfarms]

Here is what the MEP903 lugs look like



The shelter may be doing the bridging in the power control panel.

 

[quickfarms]

What is the electrical box on the floor of the tunnel, the one with cooling fans on the back of it?

 

[jamboly]

The MEP903 lug diagram makes this even more confusing. The way I read the diagram is that you can strap it for 120v OR 240v, but not both at the same time. It's back to what does the shelter need.

 

[04mustang]

So here is a little update on the project. I mounted the shelter to the trailer frame (with straps for the moment), and wired the shelter to connect to a 4 lug 30 amp twist lock civilian generator. I had planned to use my brother-in-laws 5kw generator for this to just test it out. But I found bad news and good news in doing that. His generator wasn't a 5kw, it was 6.5kw so that's good. But it only had a 4 lug 20 amp twist lock connection port and a 30 amp 4 lug will not connect to a 20 amp 4 lug port.
So...it will be a few more days before I check it all out.

Attached are several photos of the shelter on the frame and 1 of the way I wired everything together. The 4 wires on the left side of the board in that photo are for connecting batteries, I just didn't want them laying loose on the floor of the tunnel.
There was also a 1000w inverter in the shelter! so that's nice.
And the large box on the floor of the tunnel, I think, is a larger inverter and part of the power distribution system. It shows inputs of Phase A, B, and C of 208 Vac WYE, and outputs of 28 Vac @200 amp phase A, B, and C