help using all 3 phases of 804b

[LEOK]

My friend wants to use all three legs to get his 15k out of his 804b. Setup is he is in mobile home power feed from a pole with his main 200amp and trailer feed through the lug bars [see pic]. His AC two double 60amp breakers, well 20amp double, barn 20 amp single.

So what I've found is 100amp main breaker 3 phase outdoor square D box with bolt in breakers. Bring all three legs of 804 in then feed the AC's off l1, l2, then back feed trailer off l2 l3. then feed barn and pump off lightest loaded legs. I back feed the trailer by replacing trailer lugs with double tap lugs

Seems I can buy used 3 phase bolt in breakers fairly cheap. Makes it easy select legs.

Now here is the trick, when on street power the back feed won't feed l1, so put in 60amp 3phase breaker and short l3 to l1 buy turning on the breaker with jumper across l3 l1

What do you think

 

[Zed254]

When confronted with this sort of a question I call a qualified Electrician. He will know what is up to NEC standards and can keep everyone safe and secure during an outage. But that is me: I know I have a lot to learn about power generation.

 

[Farmitall]

I'll second the "call an electrician" motion.

Electricity acts in a split second and when things are wired wrong, it can cause major catastrophic damage.

 

[LEOK]

I'm really surprised, you guys jump right in fixing your units which is much more complicated than this project. I was hoping somebody else had thought of some thing I hadn't.

 

[Zed254]

You can find info if you search the SS site. This popped up when I punched in a search: https://www.steelsoldiers.com/showt...o-uses-a-MEP-804b-as-a-backup-generator/page2

 

[FloridaAKM]

I third the motion of "Call an electrician". Mobile homes & houses use single phase power, you are trying to get all the power out of a three phase generator by combining the phases, it won't end pretty. You can use three phase in your shop if your equipment is three phase & your wiring is three phase. You can wire the generator to utilize each phase separately & balance the load on each leg, but you must know what you are doing & your panel is not wired for that. Again, call an electrician; I don't want to read in the paper where a local guy had an accident with a military generator.

 

[Farmitall]

I'm really surprised, you guys jump right in fixing your units which is much more complicated than this project. I was hoping somebody else had thought of some thing I hadn't.

Not to be too controvercial but fixing/repairing a "source" of power to accomplish its published and designed output capability within its specified parameters is completely different from applying that same source of power to a circuit.

 

[Keith_J]

Don't do it that way. Phase imbalance will cause frequency issues, making the governor hunt excessively. Plus running 240 service at 208 with less current compounds the problem. This is a standard 12 lead stator brushless design. It can be reconnected in either low zig zag or double delta, netting 120/240 volt split. Plenty current for all your needs.

 

[Sephirothq]

you do know that the voltage between two legs of a 3 phase power source is 208 volts compared to the voltage between two legs of the single phase is 240 volts???

 

[uniquify]

This is a standard 12 lead stator brushless design. It can be reconnected in either low zig zag or double delta, netting 120/240 volt split.

Pretty sure the 804 has a 10-lead generator head, which is 3 phase only.

 

[microjeep]

re read first post never mind

 

[LEOK]

The AC was the one we were most concerned about. With the well I think it can the unit handle startup rushes without letting the voltage drop. I think motor speed control on the 804b is superior to the A model and will keep the frequency drop in line better.
My understanding of the dual alternator style on these unit is that it can handle different loads on each leg. What we were concerned about was if we just used two legs the AC and hot water tank was eating a significant percentage of the total available by using three legs we another 3 to 4 k to work with. What will interesting is how balanced will house load be per leg, may move some breakers around there.

I have some experience with data center building, we were using fero resonant transformer UPS's and had to balance our load so the 3 phase Cummins 12 cylinder genset didn't swing the frequency too much and keep making the UPS'S keep cutting over to battery. We open the tolerance on the UPS's moved some circuits but had one elevator of the three that had just such a hard start that you watch that Cummins jump on its spring mounts and all UPS's would go to battery. So when we lost power that elevator was shut down. It was an emergency television and radio station with roof covered with old style uplink. We really had to work on grounding we took so many lightening strikes. The EMF would fry data acquisition boards on some of dishes and we kept a pile of spares. On strike all the UPS's would shutdown but within 10 minutes we were back online. All my network gear had a dedicated separate grounding down to our 4 inch water main right as it came out of the ground. The lighting rods had there own driven rods around the building and we regular check for voltage across the grounds. I didn't like being on the roof in the storms so much steel .​

 

[LEOK]

found an 100amp main breaker 3 phase exterior box and a way mount the back feed breaker across from it with slide panel that will keep from turning both on same time only $200.00 for box

 

[LEOK]

here the panel

 

[LEOK]

Update owners doesn't like the complexity of rewiring to 3phase, looking at a 15kva transformer ~$2k

 

[DieselAddict]

What is the reason to try and shove this square peg into the round hole?

Isn't it better to buy a single phase 15kw machine if that is what they need?

Is it for sure they need 15kw in an emergency situation (assuming this is going to be used for emergency backup only)?

I'm not being a smart ass here. I'm seriously asking the questions.

 

[LEOK]

What it came down to was a combo, he really likes the mep line, quiet and diesel. He had 9000 watt screamer that didn't meet his needs. He doesn't want to manage his load on backup. The guy that sold him the machine told him was a 15k and didn't mention you can only get 10k out of it. So he looked at Kubota quiet diesel series and said mep is still cheaper even with the transformer. LP required a huge tank and during our last big one, they let people run out. So he figures 55 gallon drums will give good storage, and at sign of a storm won't be in shortage as gasoline was by the people fleeing the area. So we are both buying spare drums and running AG diesel as the most btu's per dollar. ​

 

[DieselAddict]

I recommend selling the MEP804 and looking for a MEP004. Those are 12 wire heads and can be converted to single phase. That might be your low cost and low complexity option.

 

[LEOK]

If mep were a consumer product yes, however the units are not readily available and the customer will not buy unit at an auction. He got serviced unit with a warranty, saw it run and pass a load test. He also can't stand to wait for deal, he will pay more to have it now. He went with me to pick up my unit, and the next day bought his. Tonite he said order the transformer, said you will have wait till I see the unit spec's arrive.

 

[LEOK]

More research has revealed that delta v to delta v transformer has very limit load capacity using the neutral to get 120v. Plus it does not evenly load the 3phase side either. So the story ends badly the unit will be returned with a restock fee, I don't think he should have pay it because the unit limitations were not explained but that is the deal he cut. Too bad.