I have -15- sets of 4/0 cable (1 per 32 kwh stack) into the combiner. They are paired and within .25 " of one another in wire cable tray for 80% of their respective distance.
The inverter to combiner sets are 2/0 for each respective inverter. They are paired (not twisted) in cable tray, anywhere from 10 -20' in length. Maybe I can send some photos, but can't at present due to computer issues. I used cable tray because the CT-rated cable is in free air, no derating of current required. But merely pairing the leads may be the issue. I could rearrange the inverter cables and twist the sets, but doing it from combiner to battery cabinets is impossible. And I'm wondering if this is really necessary if the customer is willing to live with the issue. What are the ramifications down the road? Loosening of connections I suppose would be one. On Fri, Jun 30, 2023 at 12:40 AM Jerry Shafer via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > Kirk > As the batteries come up to charge does the vibration subside. Are the > battery cables spun together "corkscrew like" l have seen this correct DC > noise. I have an 8 on 8 just like your 10 and l have no noise at all, mine > come in from each side of the battery combiner, how is your install > configured, how is the cable length same close or very short to very long > some length is better on FLA's due to resistance under load and charge. > More information may help with a solution. > Fun times solar > NABCEP PV Inspector > > On Thu, Jun 29, 2023, 8:19 AM Kirk Herander via RE-wrenches < > re-wrenches@lists.re-wrenches.org> wrote: > >> All, >> >> I am in the middle of commissioning a 480kwh BP LFP battery bank, >> connected to -10- OB Radian 8kw inverter/chargers. >> >> For the DC combiner I am using midnite 2000 amp combiner boxes, modified >> to mount class T fuses on the positive bus, for both battery inputs and >> inverter outputs. >> >> For starters, I set the master inverter at a max charge rate of 20 AC >> amps, which equates to a DC charge of about 74 A. All the other inverters >> are automatically set to this charge rate as well. >> >> Turning the chargers on one by one, I started to get quite an audible >> vibration from the combiner box at a combined charge of about 400 to 500 A. >> >> So I took the cover off of the combiner, which was vibrating noticabllly >> by feel. Most of the noise was from the cover not fitting tight. But the >> The box itself is also vibrating by feel. >> >> I took the combined charge up to 640A dc. This level of vibration >> definitely increases with an increased charge rate. And I am surprised >> because after all, we’re not talking AC here we’re talking DC. It almost >> reminds me of a large AC transformer in its behavior. The vibration did not >> seem to be originating at the inverters, then resonating to the combiner. >> >> I can dampen the vibration by adding a few things, but I’m surprised that >> this is happening. All connections in the combiner are tightened properly. >> Ideas? >> >> >> >> >> >> >> >> >> >> >> -- >> >> *Kirk Herander / **kirkh@vermont.solar <kirkh@vermont.solar>* >> >> *Owner|Principal, VT Solar, LLC* >> >> *Celebrating our 32st Anniversary 1991-2023!!* >> >> dba Vermont Solar Engineering >> >> 802.863.1202 >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> 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 >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> >> _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > 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 > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > > -- *Kirk Herander / **kirkh@vermont.solar <kirkh@vermont.solar>* *Owner|Principal, VT Solar, LLC* *Celebrating our 32st Anniversary 1991-2023!!* dba Vermont Solar Engineering 802.863.1202
_______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org 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 There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
