August: I read the referenced report. It does not address the concern I raised— that is the breaker specified unbonds a system that I believe is supposed to be bonded.
William > On Jul 23, 2019, at 8:38 AM, August Goers <aug...@luminalt.com> wrote: > > Hi William - > > This article is a few years old, but I think describes ground fault detection > issues well: > http://www.solarabcs.org/about/publications/reports/blindspot/pdfs/inverter_groundfault-2013.pdf > > > I don't have experience (at least since the late 90s) with the type of GFD > breaker you describe on the DC-side PV circuit. We switched to AC coupled > systems with standard grid tied inverters (transformerless non-isolated) > years ago. What kind of setup are you referring to? > > Best, > > August > > Luminalt > > > >> On Mon, Jul 22, 2019 at 1:42 PM William Miller <will...@millersolar.com> >> wrote: >> Wrenches: >> >> >> >> Here is a question that has bothered me for some time: If one is using a >> GFD (ground fault detection) breaker on a PV feeder(s) to a battery inverter >> system, the state of the industry is to use a breaker with an extra 0.5 or 1 >> amp pole. This section of the breaker connects, or bonds the DC negative, >> or grounded conductor, to the grounding system. >> >> >> >> In order for the GFD breaker to work one needs to isolate the grounded bus >> bar (negative). If there is a ground fault the breaker opens and breaks the >> bond. >> >> >> >> This goes very much against my conceptualization of how a bonding system >> should work. The bond should never be broken, particularly when there is a >> fault in the system. When this breaker opens, either manually or by an >> overcurrent condition on any pole, the DC bond is removed for all portions >> of the DC system. >> >> >> >> There is a prominent personality in the industry that often presents >> academic opinions on solar related electrical issues in articles and in >> seminars. This person claimed to have invented this GFD system, but when >> pressed to comment on the concerns mentioned above, changed the subject. >> >> >> >> I believe ground fault protection is important. I just don’t believe the >> method the industry has offered is really effective in solving the issues >> presented in a ground fault scenario. >> >> >> >> I believe similar issues present on non-battery PV systems with the simple >> fuse in the ground system found on many inverters. I know some >> troubleshooting guides warn of energized parts in ground fault conditions. >> >> >> >> Have any of you thought about these concerns? Are my concerns valid? What >> are your policies on this subject? >> >> >> >> Thanks in advance for any insight. >> >> >> >> William Miller >> >> >> >> Miller Solar >> >> 17395 Oak Road, Atascadero, CA 93422 >> >> 805-438-5600 >> >> www.millersolar.com >> >> CA Lic. 773985 >> >> >> >> Quote of the month: “As they age, batteries transition from energy >> >> storage devices to energy consuming devices.“ W. Miller >> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> 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 >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >>
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