Wrenches, Is it a "special" transformer that will give you the 180 deg phase shift from the original 120 deg shift?
Thanks On Fri, Oct 21, 2011 at 5:52 PM, William Miller <will...@millersolar.com>wrote: > Friends: > > I posted a question here about three weeks ago on the subject of connecting > a dual SW inverter stack to a three phase generator. I have learned a lot > since then. Here are the most important points: > > Most large, three phase generators are allegedly field convertible to be > either 208 or 240 three phase. The 208 version is probably wye configured > and the phase angle between any two phases is 120 degrees. If you connect a > 120/240 inverter system (even numbers of Outbacks, two SW's or XWs > configured single phase, and maybe other models) across two of the phases, > the 120 degree phasing will cause the inverters to puke. If you purchase > and connect the correct transformer across two of these phases and you will > provide the 180 degree phase angle you need but you will imbalance the > generator. For a large (30KVA or larger) generator, the 10 KVA of imbalance > is not a big issue. Your transformer will cost about $1,000 delivered and > will weigh about 200 pounds. > > You can swap some connectors and have a 240 configuration which will > probably have a "stinger" leg. If it does, the windings are probably a > delta with one winding center tapped. If so, the phase angle between the > two phases on either side of the neutral is 180 degrees. You can connect > your Outbacks (or others) across these two phases and neutral without a > transformer. You'e saved your client $1,000 and yourself a hernia. > > If the customer can live with a stinger then you have your cake and eat it > too: Three phase for 240 VAC loads and a 120/240 single phase inverter > system for 120 or 240 VAC loads. > > This realization was huge to me. Think about it... > > William Miller > > PS: Just replacing a 3 phase panel with a single phase panel does not give > you 120/240 with 180 degree phase angle. > > Wm > > > > > At 08:23 AM 10/21/2011, you wrote: > > Do they actually have 208v loads? If not, replace with 120/240 panel. Just > a thought... Although a transformer would be required to use an existing > 208v generator. > > Jason Szumlanski > > On Oct 21, 2011, at 11:17 AM, "Allan Sindelar" < > al...@positiveenergysolar.com> wrote: > > Wrenches, > We have been asked for a design for an off-grid system to reduce generator > runtime for a mountain resort. Initial projections (consumption measurement > results not yet available) suggest 15-20 kW of PV and around 30 kW of > inverter capacity. However, the generators and existing wiring are > three-phase 120/208. > > My assumption is that our only options are a set of six Sunny Islands, or > 9-12 Outback GVFX3648s. Are there any other options or approaches that I'm > missing? > > Thank you, Allan > -- > > *A* > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > > -- Mac Lewis * "Yo solo sé que no sé nada." -Sócrates *
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