Ferrite cores can be used for the battery cables to pass through to reduce common mode current
On Fri, Jun 30, 2023 at 3:59 AM Kirk Herander via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > 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 > >
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