Nice job guys ! Taming RFI is often a tedious and difficult job.
Here is a good reference piece from Jim, K9YC for anyone interested :
Here is a good reference piece from Jim, K9YC for anyone interested :
RFI issue
- Thread starter Cagire
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You can add Victron MPPT’s to that list. I’ve not used their inverters.
The RFI can be tamed but it’s a DIY thing despite them being aware of the problem.
From the link above. Looks like 14 turns on 1 core is optimal for attenuation between 2 - 10 Mhz. In my experience trying to attenuate RFI from Victron MPPT, stacking more cores made things better. But it's clear how winding capacitive coupling takes over > 10 Mhz with too many turns. Would be interesting to measure it with 30 turns. Would probably have around 10Kohm impedance but at narrow freq. range around 2MHz and steep roll off at freqs above.
Very interesting document with real measurements. thank you. I will haveto print it at read it because it's quite a piece.
I think I will read the document for my own comprehension. If I decide to modify my toroids, I could measure them. I have a nanoVNA and I've been successfully measuring impedances and inductances so far.
I don't think it would matter at RF. C5 is there to couple neutral to ground when bond is open.
wpns
Solar Joules are catch and release
Only if you've tuned your array to be resonant on a particular band and are using it for an antenna. 8*)
I found a link and I noticed the guy put the LC filter before the toroids (he ie using type 31 and type 43). I wonder if that matters.
gm3sek.com
I have a type 43 on hand and could add it to the AC-out filter. I could also switch the order between the LC filter and the toroids. For now, it's a bit misterious to me all that RFI stuff. Since I don't understand (yet) fundamentally how it works, I have to work a bit randomly and experimentally ^^
Clean Up Your Shack – 2019
The online follow-up to my talk for the 2019 RSGB Convention. What’s new since 2015 Choke Chart and RadCom Plus article by Steve Hunt G3TXQ (SK) – see separate blog entry below Revised …
gm3sek.com
I have a type 43 on hand and could add it to the AC-out filter. I could also switch the order between the LC filter and the toroids. For now, it's a bit misterious to me all that RFI stuff. Since I don't understand (yet) fundamentally how it works, I have to work a bit randomly and experimentally ^^
Good luck for 160 m haha
wpns
Solar Joules are catch and release
And of course the RFI environment is getting worse all the time, add a weather station, a Smart Plug, a different inverter, a Raspberry Pi running Solar Assistant, a switching golf cart charger, and suddenly you are off on another Snark Hunt.
wpns
Solar Joules are catch and release
Just need a big array. Win/Win!
That line filter most likely cleans up differential mode RFI followed by ferrite to choke common mode.
wpns
Solar Joules are catch and release
And of course, if you have RSD make sure you don't block the enable frequency, though I think that's in the 150KHz range...
My RFI issues came from the SCC and a Mix31 on each wire dropped from S9 to barely perceptible. The higher the frequency, the worse it was from me. Someone mentioned cheap getting rid of cheap inverters and chargers but my Victron 250/100 is much worse than a BougeRV 60a SCC, virtually silent with no filtering.
Additionally, paralleling the Mix31 cores physically from each wire together, further reduced it.
Additionally, paralleling the Mix31 cores physically from each wire together, further reduced it.
wpns
Solar Joules are catch and release
Ah, now that I think about it, the MPPT is going to be differential mode, so common mode chokes aren’t going to help a lot.
Hedges
I See Electromagnetic Fields!
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Separate choke around ground, and isolating inverter chassis, don't feel right from an EMI point of view (and isolating from safety point of view.)
L/N/G all through a choke seeks to keep sum of those currents equal to zero.
Inverter may have LC filters in power line, with noise injected into chassis. I think that should have hard connection back to earth, so nothing is driven common-mode relative to earth. (going through same choke as L & N should be good.)
Common-mode chokes are what is typically added as band-aid for EMI. LC filters could help, more difficult to size properly and install, of course.
Hedges
I See Electromagnetic Fields!
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I hadn't thought of MOV to protect cap. Cap for AC line ought to withstand kV transients typically seen on lines.
LC filter as you describe matches what I was thinking of.
For PV, some inverters spec max capacitance to ground for panels because they do a leakage check and superimpose AC. I think the leakage check is brief grounding of PV- and of PV+, so capacitance would be a momentary current flow. The inverters I have, looks to me like feeding 208V of 3-phase drives 60 Hz 60Vrms common mode, 240V single phase drives 120V, 120/240V split-phase doesn't drive AC.
The square wave you mention, is that MPPT or is it due to non-isolated from AC?
RSD keep-alive or communications would be differential mode current. If using external keep-alive transmitter, just put these filter components between that transmitter and the inverter. If internal, don't want to kill the signal with capacitance between the two lines. What bandwidth? filter could have band pass, in this case "band not stop" since it is a shunt.
You may be able to put capacitance from a single wire PV- to ground but not PV+ to ground, so keep-alive isn't absorbed. Of course, that asymmetry would convert common-mode noise to differential. Basic problem is passing desired signal and blocking the rest. Chokes before and after the shunt capacitance, band pass filter to jumper around it?
Just a bulk capacitor which passes (shunts or shorts) MPPT frequency ought to work. Needs to not affect keep-alive frequency. An inductor in series with cap could tune to be high frequency for that. Does low impedance to 15kHz MPPT, high impedance to 150kHz keep-alive sound right? one decade, about 20 dB. Not huge, but something.
I'm a bit lost to be honest, I'm not so advanced in electronics sadly ...
If I recap, you suggest twisting N + L + G and wind them in the same toroid on AC-output, right ? Same for DC-panels-input or not ?
No I don't, I have a little oscilloscope though, if it can be any usefull.
Do you mean something like this ?
I could build one I guess.
If I recap, you suggest twisting N + L + G and wind them in the same toroid on AC-output, right ? Same for DC-panels-input or not ?
No I don't, I have a little oscilloscope though, if it can be any usefull.
Do you mean something like this ?
I could build one I guess.
Non-isolated from AC. Low frequency 50Hz commutating half-bridge of DC-AC inverter stage connects N wire to positive internal HVDC rail and on alternate half cycle to negative rail. When it connects positive to neutral it causes PV- to become negatively biased in relation to ground by HVDC voltage typically -450V.
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