Thanks for your suggestions. I wanted to get ideas before heading out the site since it is 4 hours away and in the middle of nowhere with no local resources!
I'll followup once I go visit. thanks, Troy Harvey --------------------- Principal Engineer Heliocentric 801-453-9434 tahar...@heliocentric.org On Feb 12, 2014, at 11:43 AM, Ray Walters <r...@solarray.com> wrote: > I just had an idea on this situation from August's comment. I'm sure you've > checked already, but are you sure that ground and neutral aren't bonded in > both locations, causing current to flow through the ground system? I've seen > many multiple building properties inadvertently send both a ground wire and > neutral to a separate structure with neutral bonded to ground in both > locations. > If the separate structure has its own grounding system and bond, then > disconnect the ground wire connection back to the other building, as it will > still be bonded through the neutral. The other option is to set a separate > ground buss in the load center at the separate structure, and unbond neutral > from ground, since it would bonded back at the other building. > Just an idea, I've seen all sorts of weird things happen with current flow > on the ground. If you have uneven current flow on that long a run, it could > definitely cause some issues. > > R.Ray Walters > CTO, Solarray, Inc > Nabcep Certified PV Installer, > Licensed Master Electrician > Solar Design Engineer > 303 505-8760 > > On 2/12/2014 9:14 AM, Exeltech wrote: >> Troy, >> Elsewhere in this thread, boB (Midnite) suggested connecting one of the >> problematic lights and dimmers directly at the inverter output. >> This is a very sound recommendation, and would immediately rule in .. or >> rule out the conductors (and related circuits) as an issue. >> Another Wrench suggested using an oscilloscope to check the waveform at the >> load end. This too is excellent advice, and would be even more telling than >> connecting the lamps and dimmer directly at the inverter. The ‘scope will >> reveal the AC voltage AND a visual indication of any waveform distortion, >> either aspect of which could potentially cause the flicker you describe. >> If you don’t have access to a ‘scope, boB’s comment about connecting at the >> inverter won’t require any test equipment. >> At a minimum, set your DVM to record the voltage minimum; connect it the >> lamp circuit, and turn on the 1 kW load you described. If the voltage is >> dropping notably, this too would introduce visible flicker. The DVM method >> is less accurate than an oscilloscope, but better than nothing, and depends >> greatly on the quality (or not) of your DVM. >> The above aside, anything else would be strictly conjecture .. which we can >> do all day, and never be correct. >> Dan >> -------------------------------------------- >> On Wed, 2/12/14, August Goers <aug...@luminalt.com> wrote: >> >> Subject: Re: [RE-wrenches] Long transmission line inductance and LED light >> flicker >> To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> >> Date: Wednesday, February 12, 2014, 9:01 AM >> Hi Troy, >> >> Have you double checked that your grounding systems both in the house and at >> the inverters/array are all up to snuff? >> >> Sorry I can’t offer any help with the inductance issue. >> >> Best, >> >> August >> >> >> From: re-wrenches-boun...@lists.re-wrenches.org >> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Troy Harvey >> Sent: Tuesday, February 11, 2014 5:45 PM >> To: RE-wrenches >> Subject: Re: [RE-wrenches] Long transmission line inductance and LED light >> flicker >> >> >> Richard, >> >> >> The system configuration is: >> Approx 24.7kW of modules connected to: >> 2 x 9kW Sunnyboys >> 1 x 5kW Sunnyboys >> >> Plus >> 4 x 6kW sunnyislands, with 2 Parallel 48V Strings of (12 x 4V Surrettes ) >> using 350MCM cable >> >> >> >> Wire >> >> The wire is about 1000 feet long 350 MCM in a "twisted" bundle to this >> outbuilding >> >> Conditions >> >> The conditions were during the day with full sun, so during the test there >> is approx. 47kW of available inverter pointed at only >15 amps (120V) of >> load(!). >> >> The steady state conditions was a few LED lights, maybe 60 watts worth, plus >> a handful of vampire loads, maybe 100-200 watts total. When a pure >> resistance load, like a 1000W curling iron was turned on the lights would >> flicker. >> Since the lights flickered from a resistive load, but didn't stay dim, I >> assumed it was from a reactive-phase issues due to the transient turn-on - >> screwing with the LED dimmer circuits which are already doing a bit of magic >> to turn TRIAC waveforms into a DC constant current. >> >> thanks, >> >> Troy Harvey >> --------------------- >> Principal Engineer >> Heliocentric >> 801-453-9434 >> tahar...@heliocentric.org >> >> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change email address & 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 >> > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & 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 >
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