Bill Brooks posted this in 2008. A couple of project-specific sentences were removed to avoid confusion.
"The 6kVA value comes from the California Rule 21 that I worked on. It only applies to split-phase 240V systems (6kVA on 120V). There is no specific limit for imbalance on a 3-phase service. A basic rule for single phase generation on a 3=phase service is to rotate among the phases in a balanced manner... ...The best way to place the imbalanced single-phase generators on the service is to test the current on all three phases and put the inverter(s) on the most heavily loaded phase(s). This reduces the site imbalance by reducing the imbalance on the serving transformer (lowering current on the most heavily loaded phases). It is common for 3-phase services to have imbalances of 10 kVA or more, so single-phase inverters can reduce the problem rather than make it worse." For a brighter energy future, Andrew Truitt NABCEP Certified PV Installer™ (ID# 032407-66)**** Principal Truitt Renewable Energy Consulting**** (202) 486-7507**** http://www.linkedin.com/pub/andrew-truitt/8/622/713 "Don't get me wrong: I love nuclear energy! It's just that I prefer fusion to fission. And it just so happens that there's an enormous fusion reactor safely banked a few million miles from us. It delivers more than we could ever use in just about 8 minutes. And it's wireless!" ~William McDonough On Tue, Nov 27, 2012 at 3:33 PM, Chris Mason <cometenergysyst...@gmail.com>wrote: > I really don't understand what your problem with this arrangement is. > How would this be different from a house on phase A-B installing an > inverter and the next house on Phase B-C installing an inverter? Or, > installing two single phase 240V A/C units in a three phase building? > Electricians have no issue with installing single phase equipment in three > phase buildings so why should small inverters be any more a problem. > While it is always neat to install three inverters n a three phase > configuration, 4,500 watts of imbalance is trivial. > > > On Tue, Nov 27, 2012 at 3:59 PM, <hol...@sbcglobal.net> wrote: > >> ** >> We were asked to inspect a GT system installed by others. Service is 208 >> 3ph with two (?) Fronius IG 4500 208v inverters. The inverter panel is 3ph >> with two 2pole breakers - one each side of the buss bar in a A/B, B/C >> configuration (??). Called Fronius and they said it would work, but they >> "don't recommend it". No other information was given as to why they don't. >> My electrician is very uncomfortable with doing work on this system as is >> (ME TOO!), so I am wondering if I might be able get some ammo to convince >> system owner to add a third inverter to get the system right. What problems >> might/will be encountered in this system if not modified? BTW - inverter >> LCD screens were crapped out, so we couldn't readily see if system was >> functioning properly....from metering, we think not. >> >> >> Holt E. Kelly >> Holtek Fireplace & Solar Products >> 500 Jewell Dr. >> Waco TX. 76712 >> 254-751-9111 >> www.holteksolar.com >> >> _______________________________________________ >> 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 >> >> >> > > > -- > Chris Mason > President, Comet Systems Ltd > www.cometenergysystems.com > Cell: 264.235.5670 > Skype: netconcepts > > > _______________________________________________ > 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 > > >
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