HI Allan, The only reason to frequency shift is for “softer” charging. VRLA are not as sensitive to the pulse type charging that a relay type charging would do. And regardless if you have frequency shift or not, you will still need ( especially with VRLA) a high voltage relay. I recommend a SS relay, but a regular mechanical contactor will do as well.
jay Peltz Power. > On Apr 4, 2016, at 12:34 PM, Allan Sindelar <al...@sindelarsolar.com> wrote: > > Wrenches, > Core question first: Will a ~2010 Fronius IG-4000 respond properly to the > frequency shift regulation supplied by a new Schneider XW+5548 or XW+6848? > > Situation: I haven't seen the Colorado site; I'm working as a consultant to > produce an upgrade component list and will later serve as a resource during > local installation of the upgrade equipment. Customer has hired me to turn a > hodgepodge system into a GTBB system. The system has two key parts: an > existing SW5548 with batteries, never properly installed (only AC1 in was > ever connected to a main load center!) with 3.1 kW of tracker-mounted PV > through an Outback FM60; and a roof-mounted 4kW array feeding the grid panel > via the IG-4000. As currently installed, nothing will operate as wired during > a grid outage, and a 240V AC well pump isn't supported. > > The simple plan is to replace the SW5548 with an XW+5548 or 6848 with Midnite > E-Panel; replace batteries with Surrette FLAs; keep existing arrays > unchanged; use existing FM60 for smaller tracked array; use existing Fronius > IG-4000 but AC couple it to the output of the XW. The customer understands > that sell amperage is limited by the inverter (to 20A @ 240V for the 5548, or > 4,800W, or 27A @ 240V for the 6848, or 6,480W) when the grid is up, but the > full array can charge the battery bank when the grid is down. > > Schneider tech support assures me that the XW+ is good in this application, > but I need to get an OK from Fronius about frequency-shift compatibility. > Fronius tech support tells me that it may or may not work: the 0.4 hz shift > is within the the normal frequency tolerance for this model. While the > tolerance window may be tightened up in the field, such tightening may cause > nuisance tripping, especially with reactive loads like a well pump or A/C. > The tech suggested that we first test the frequency-shift approach, and add a > DC-coil contactor between the output of the Fronius and the XW+ if it doesn't. > > Has anyone AC coupled these two units? Did it work? Any unexpected problems? > Did you add a voltage-controlled contactor? What should I advise my client? > Thank you, > Allan > -- > Allan Sindelar > <mailto:al...@sindelarsolar.com>al...@sindelarsolar.com > <mailto:al...@sindelarsolar.com> > NABCEP Certified PV Installation Professional > NABCEP Certified Technical Sales Professional > New Mexico EE98J Journeyman Electrician > Founder (Retired), Positive Energy, Inc. > 505 780-2738 cell > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > <mailto:RE-wrenches@lists.re-wrenches.org> > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > <http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html> > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm <http://www.re-wrenches.org/etiquette.htm> > > Check out or update participant bios: > www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >
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