I have not twisted them. It is a lot of Cable as you might imagine and they aren’t paired close together individual inverter to combiner or combiner to battery cabinets, not 100% of the cable lengths anyway, maybe on average 80%
On Thu, Jun 29, 2023 at 12:25 PM Starlight <la...@starlightsolar.com> wrote: > You may already know but… Are your DC cables bonded together and twisted > where possible to reduce magnetic fields? Higher the current and greater > the loop area, the stronger the fields are. More parallel loops, the > greater the combined flux = loud Hums. > > Larry Crutcher > Starlight Solar Power Systems > > > > > On Jun 29, 2023, at 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 > > > -- *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
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