split a phase ??? combine a phase ???

[t1mower]

i have a 66 amp/ 8000 watt 1 phase 120 volt  onan variable speed diesel in my rv.  i believe i can but figured id check with you guys 1st.
  1st when the rv is  plugged into a 50 amp outlet ( trailer park) we actually get a true 240 volt power ( 2-120's).  but when plugged into a 30 amp service our pigtail adapter that connects our 4 wire plug into a 3 wire plus ( 1-120).  so i believe that our genny ( 3 wire ) is actually somewhere wired inside to do exactly what this pigtail is doing !   i want it to do the same but just not to power the rv but power my house .


after pulling main breaker at grid. for use as emergency standby  can i connect my one phase from the genny to the 2 hot lines as a split or more exactly as a combiner as long as i disable anything i have that runs 220 as ex. air compressor, stove, etc.  .

i believe that as long as i only run lighter 120 loads like lights,fridges,tv etc it could work. my main power panel  i installed is very balanced when i have it on my 20 kw 240 volt genny now. volt difference between each leg is 1.0 to 1.5 volts difference.

  i'am  doing this simply because  my  30 kw/ 3 phase ( 12 wire head)  rewired to 20 kw/ 1 phase  4 cyl diesel cummins  rated at 125 amp/ 3ph   isn't working hard enough when i do a off grid test.  when fully loaded i pull 60 amp at 240  if i only run the bare loads i pull about 20 to 30 amps.  so im not loading the genny heavy enough to make it efficient for the load i'am useing.

i figure the rv genny will be more closely matched to the load which is better for the engine and also more fuel efficient
the big plus its a 3 cly diesel with the new load system.  its max load rpm is 3600 but as the load gets lower the rpms follow going down with the load until it gets to a idle.  that within itself is big fuel saver as when going to bed.
 
and yes i wish i had a slow speed lister petter with a 240 volt 1 ph head about 10kw  ( i'm searching ) looking for a barn find !   then i can get really going for it to run on my wmo as like all my other off road equipment.
possible to sell my 30kw and use the money for the lister ?  and also to the wmo guys a industrial centrifuge is the way to go for oil cleaning. i will be posting in another topic my procedure for good clean oil.
  side note i heat my house and garage ( both big) with a wmo boiler.  total cost mostly elect for a whole season is about $150.  that part i got down.

  id like to thank any replies in advance  as this is my 1st post on this forum with hopefully more to come.   very close to off grid now hopefully all the way some day.   
                   t1mower
   
   

[TimSR2]

I believe your RV air conditioners run on 240v, RV gensets are 240v center tapped for 2 legs of 120v just like your house. This should be no problem.

You could actually do this whole thing to code.  Install  a proper transfer switch and generator feed plug  on the house, and add  an output plug or cable to the RV (twistlock).  A 10 gauge cab tire cable to connect the RV to the house and you are all set.

[t1mower]

rv a/c's run on 120 ,  when plugged into a 30 amp there is only black,white,green

[TimSR2]

Hmm.  Now you have me thinking.  In the RV park you can often get a 15 amp hookup or a 30 amp hookup.  The 15 amp  feeds only one leg, and your a/c won't work. But the 30 a hookup has 2 'hots' and will feed your ac. I think we both assumed this meant 230v.
  I just had a look on the Onan site and I see that  the hots  are in phase, so  I stand corrected.  Still, you could set it up to feed the house, but no 230 volt loads  could be supported. 

So from what I gather the 30 amp hookups in the trailer park  are in phase 120volt, and and not 230 volt . see here. 

http://www.myrv.us/Imgs/PDF/30-amp%20Service.pdf

[t1mower]

yes you got it  15,20,30 amp are all 1 hot leg.  50 amp is 2 hots.   heres the trick they do! when you have a 4 wire ( 2 hot legs) 50 amp plug as i do on the rv.  there is a adapter pigtail you plug into then it comes out with the 30 amp plug  and inside the adapter it actually takes the one leg from the 30 and combines the 2 legs on the rv plug.
  its done this way as many parks dont have 50 amp service. 

i'm going to try and get my  onan 8000 hdkak schematic to see whats actually up.  i looked yesterday real quick and it says 2 pole 33 amp.  something is amiss here.
also noticed it said (spec k) so maybe it got the  why,delta, cross thing going  ( like a 12 wire head ) .     
   but when i looked at the wire hookup inside panel  it had black,white,green.   maybe the rv manufacturer actually used the green as a hot since this whole unit is mounted in the frame and would be considered grounded.  not safe but  these guys will sometimes do cheap things to save a buck or 2 on wire    will get the volt meter out tomorrow maybe.

[t1mower]

heres something quick i found .  http://www.cumminsonan.com/www/html/Common/pdf/specsheets/a-1408.pdf..

dont think mines a qd but close   think this is just a newer model

[t1mower]

found another   its a dogbone !


50 Amp to 30 Amp Dogbone Adaptor

At times it becomes necessary to power an RV with a 50 amp service when there is no 50 amp receptacle available. The standard 50 amp receptacle is a NEMA #1450R. Unlike the 30 amp NEMA TT-30R, this isn't an RV-only receptacle and can be found in industrial applications as well. It's a 4 prong outlet that has two hot wires - L1 and L2, as well as a neutral and ground wire. Any RV dealer or RV accessory store will offer an adaptor, that is commonly referred to as a dogbone adaptor, which is illustrated above. This adaptor will let you adapt your 50 amp plug to a 30 amp so that you can plug your 50 amp RV into a 30 amp RV receptacle if that's all that is available. When you do this you'll be limited to 30 amps of power though. The dogbone adaptor will connect the single 120 volt hot pole to both the L1 and L2 inputs of your RV's 50 amp breaker panel. When you do this you will have the same phase across L1 and L2 so there will be no 240 volts available. But, seeing as how 99.9% of the RVs made don't use anything with 240 volts that's not a problem. In this situation all of the power will be going down the neutral wire. But, you are only sending 30 amps to the panel and your neutral wire is rated to handle 50 amps so you'll be fine. You will have to be careful to manage your loads when running on 30 amps. If you fire up all of your air conditioners and water heater you are going to blow that 30 amp pedestal breaker so you have to watch what you turn on. You can also add a second adaptor to change the 30 amp down to a 20 amp plug if you have to but then all you're going to be able to do is keep the batteries charged and maybe run a few lights

In the next section we'll talk about transfer switches and how they switch between shore power and a generator set.

[TimSR2]

Note that on the cummins/onan site the diesel 10 kw genset is described as 115/230v, consistent with what you describe as 50a service. 

Your generator head could be rewired internally for 230/115v...  We do it all the time with the st heads.  Just reverse the polarity of U1/U2, or U3, and U4.  Your neutrals will be tied together at the generator, and bonded to ground. Reverse one of the windings and you have a 115/230v generator.  As there are no 230 volt loads in the RV it's no use,  and no harm  to it,   but it would sure make it useful as a home backup system. 

Any generator head that provides   2 sets of 115 volt outputs is a possible  candidate for easy 115/230 volt conversion.  A little more research perhaps.

But if you make this conversion you must be aware that if you plug into a 30a plug in the rv park while your generator is running there are going to be some breakers tripped..

[t1mower]

well figured it out !  they are running two 120's ( 30 amp) same phase out of the genny combining them at the genny to run a total of 60 amps to the transfer switch.   when on shore power they are letting in 220 ( out of phase) in ,  but when on genny they combine the 120 to feed the 2 legs . since nothing is 220 in the rv all is fine.

  i ran my garage yesterday on the rv genny with all my 220 stuff breakers off i just crossed or combined the 2 panel bars and all was fine.  so i guess it can be done.

[t1mower]

the transfer switch cuts the genny power 100% to coach  as soon as the shore power is plugged in.  so should be ok if i go that direction .