<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:12pt"><div><span>jm7 y first thought is a bad neutral connection, it could be heavy neutral current do to harmonics, The grow lights put a load on the neutral by third harmonic. I have seen a switch gear burn up after we put the school on electronic balasts. </span></div><div><span>Darryl</span></div><div><br></div><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt;"><div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"><font size="2" face="Arial"><div style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); height: 0px; line-height: 0; font-size: 0px;" class="hr" contentEditable="false" readonly="true"></div><b><span style="font-weight: bold;">From:</span></b> Nathan Jones <solardude97@yahoo.com><br><b><span style="font-weight: bold;">To:</span></b>
re-wrenches@lists.re-wrenches.org<br><b><span style="font-weight: bold;">Sent:</span></b> Sunday, November 13, 2011 3:12 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [RE-wrenches] Strange voltage readings, power quality<br></font><br>
Mac,<br>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.<br>Nathan Jones<br>Power Source Solar<br>417-827-0738<br>On Sun, Nov 13, 2011 10:55 AM CST mac Lewis wrote:<br><br>>Hello wrenches,<br>><br>>I am having an interesting grid-tied issue and would love to get some input.<br>><br>>The installation is 3 Fronius IG Plus inverters all single phase, two 7.5s<br>>and one 10.0. The service is 120/208. We have the two 7.5s feeding a<br>>dedicated 3 phase sub and tied back into the main panel after production<br>>meter. The first 7.5 is tied across Va to Vb, the
second is tied in across<br>>Vb to Vc. The 10.0 feeds directly back to the main panel after production<br>>meter and is tied in across Va to Vb.<br>>It should be noted that this facility has very large capacitive load, about<br>>25 kW of grow lights. According to an egauge on site, the power factor<br>>ranges from 0.5 to 0.75 on all phases.<br>>The system worked flawlessly for 3 months, suddenly the two 7.5s dropped<br>>out and gave a myriad of grid errors, everything from islanding errors, to<br>>high grid voltage, and low grid voltage etc.<br>><br>>I went over there and found the phase B voltage to neutral, was way out of<br>>wack, anywhere from 120-170. Oddly, the Line to line voltage was fine,<br>>right around 208 for all phases. I called the power company and had them<br>>install a monitor at the transformer. After 5 days they came back and said<br>>that their end was within
spec. I decided to put both of the 7.5s between<br>>Va to Vc. They would not boot up. I then went to the main panel and<br>>changed the physical location of the breaker for the subpanels of the 7.5s.<br>> This seemed to make the difference. They booted up and are exporting<br>>power. I tried switching one of the 7.5s back Va to Vb, but it still would<br>>not boot up unless it is connected from Va to Vc.<br>><br>>My working theory right now is that we are getting harmonics traveling back<br>>to the inverters from the ballasts on the grow light across line B. As far<br>>as explaining why it suddenly happening, my guess is that he has started<br>>turning off inductive loads such as fan motors and compressors as we are<br>>entering the winter. There may have been a filtering effect going on with<br>>the motors absorbing some of these harmonics and attenuating them. I
am<br>>going to try to verify this with an oscilloscope this week.<br>><br>>Does anyone have any other theories to explain this type of behavior?<br>> Anyone seen this before? Should I look for anything else?<br>><br>>Thanks<br>><br>>Mac Lewis<br>><br>><br>>-- <br>><br>><br>><br>>Mac Lewis<br>><br>>*<br>><br>>"Yo solo sé que no sé nada." -Sócrates<br>>*<br><br>_______________________________________________<br>List sponsored by Home Power magazine<br><br>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org" ymailto="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a><br><br>Options & settings:<br>http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org<br><br>List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org<br><br>List rules & etiquette:<br><a href="http://www.re-wrenches.org/etiquette.htm"
target="_blank">www.re-wrenches.org/etiquette.htm</a><br><br>Check out participant bios:<br><a href="http://www.members.re-wrenches.org" target="_blank">www.members.re-wrenches.org</a><br><br><br><br></div></div></div></body></html>