Mac, I have encountered two battery based inverters that were affected by the feedback frequency of CF bulbs. One would trip and show overload from a single 15 watt bulb with no other loads connected every time. The other one was an intermittant situation. Had I not encountered this problem before I might still be trying to figure that one out. I think it would be worth ruling out as a possibility at this point. Nathan Jones Power Source Solar 417-827-0738 On Sun, Nov 13, 2011 10:55 AM CST mac Lewis wrote:
>Hello wrenches, > >I am having an interesting grid-tied issue and would love to get some input. > >The installation is 3 Fronius IG Plus inverters all single phase, two 7.5s >and one 10.0. The service is 120/208. We have the two 7.5s feeding a >dedicated 3 phase sub and tied back into the main panel after production >meter. The first 7.5 is tied across Va to Vb, the second is tied in across >Vb to Vc. The 10.0 feeds directly back to the main panel after production >meter and is tied in across Va to Vb. >It should be noted that this facility has very large capacitive load, about >25 kW of grow lights. According to an egauge on site, the power factor >ranges from 0.5 to 0.75 on all phases. >The system worked flawlessly for 3 months, suddenly the two 7.5s dropped >out and gave a myriad of grid errors, everything from islanding errors, to >high grid voltage, and low grid voltage etc. > >I went over there and found the phase B voltage to neutral, was way out of >wack, anywhere from 120-170. Oddly, the Line to line voltage was fine, >right around 208 for all phases. I called the power company and had them >install a monitor at the transformer. After 5 days they came back and said >that their end was within spec. I decided to put both of the 7.5s between >Va to Vc. They would not boot up. I then went to the main panel and >changed the physical location of the breaker for the subpanels of the 7.5s. > This seemed to make the difference. They booted up and are exporting >power. I tried switching one of the 7.5s back Va to Vb, but it still would >not boot up unless it is connected from Va to Vc. > >My working theory right now is that we are getting harmonics traveling back >to the inverters from the ballasts on the grow light across line B. As far >as explaining why it suddenly happening, my guess is that he has started >turning off inductive loads such as fan motors and compressors as we are >entering the winter. There may have been a filtering effect going on with >the motors absorbing some of these harmonics and attenuating them. I am >going to try to verify this with an oscilloscope this week. > >Does anyone have any other theories to explain this type of behavior? > Anyone seen this before? Should I look for anything else? > >Thanks > >Mac Lewis > > >-- > > > >Mac Lewis > >* > >"Yo solo sé que no sé nada." -Sócrates >* _______________________________________________ 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
