James:
Jim (K9YC) gave TJ recommendations on the type of chokes that were to be
installed on my neighbors installation. However, I'm not sure how much
of Jim's design was actually used.
Have you had the time to evaluate the RFI since the chokes were
installed? Can you give us a before and after evaluation on the noise?
Tony -K2MO
On 9/25/2020 8:33 PM, WW3S wrote:
Tom, aka TJ, is pretty good.....you are correct, he doesnt like Tonys
article from Arpil 2020, not sure why, but the retrofit they did at my
neighbors was very similar except they used clamp on ferrites, big son
of a guns.....Paul is probably monitoring, he can chime in if he
wants, but the engineer I had was Mike, and was very familiar with the
work done at Pauls....I didnt get a good look at the ferrites, they
were already on the roof when I saw them, but they twisted the heck
out of the wiring, and replaced all the optimizers.....Paul thought
they used type 31 ferrite, but in an email from TJ, he said the used a
type 75, ECM-IN-66OHM (maybe their part #)...he also said they
eliminated a ground fault pitch point ?!?!?!?
------ Original Message ------
From: "Tony" <73guddx@gmail.com>
To: "Rfi List" <rfi@contesting.com>
Sent: 9/25/2020 8:03:23 PM
Subject: Re: [RFI] Question Regarding Variations In Solar Panel RFI?
Jim:
Tom Simpson (Solar Edge Engineer) will be visiting the site sometime
in the near future so I'm hoping he'll address the potential problems
you mentioned.
The issues you describe may also explain why the suppression hasn't
been very effective. The noise was 15db over S-9 prior to the
suppression being installed and it's now S-9 plus a tad for a
reduction of roughly 10db.
This installation may require the methods used by Tony Brock-Fisher
which includes chokes between the inverter and mains which is
something Solar Edge frowns upon. Not sure if it's a cost or a code
issue.
Thanks Jim.
Tony -K2MO
On 9/25/2020 6:49 PM, Jim Brown wrote:
Tony,
There are MANY variables and wiring errors and system layout errors
that can contribute to how much RFI is radiated. One issue that Teff
communicated to me was that the framing holding the panels was
bonded to ground on the other side of the building from the power
entry. If this is true, it creates a current loop that could be
causing or contributing to your problem.
Wiring can be prevented from radiating by shielding, IF, AND ONLY
IF, the shielding is continuous. In the real world that I'm aware
of, the only shielded AC wiring is that which is enclosed in steel
conduit, that is continuously bonded together. That's quite rare in
residences, except in cities like Chicago, where the Electricians
Union has it written into the city's Electrical Code as a means of
providing more work to Electricians.
Running twisted pair for power can prevent radiation from the
current-carrying conductors (phase and neutral), but won't help with
common mode RF current, which is nearly always on the green wire.
And the common mode current is there because of bonding failures,
either in the construction of the equipment itself, or in the
installation, or both.
The wiring inside the home could be hot with RF as a result of
wiring errors at outlets, at panels (double-bonded neutral), even
bonding at equipment. At the home I bought in California, I found an
outlet wired with neutral and ground reversed, and I found outlets
in the kitchen of a "mother-in-law" garage apartment fed between
phase and green rather than phase and neutral. I also found no
ground at all at the service entrance -- it was bonded to a hose
outlet that was fed by PVC pipe!
73, Jim K9YC
On 9/25/2020 3:22 PM, Tony wrote:
All:
The reports I've read suggest that the strength of interference
caused by solar panel systems can vary from one installation to the
next EVEN when the distance to the source is similar. That
variation could be attributed to radiating conductors tied to the
system such as the house wiring.
We found high levels of RFI on the A/C lines throughout my
neighbors home and that's likely the case with all Solar Edge
installations since there are no chokes between the mains and
inverter.
Given those facts, would a large home with long runs of un-shielded
Romex produce higher levels of interference compared to a smaller
home with shorter runs? Or does the resonance of the wiring play
more of a role than length and number of runs?
It's an oversimplification, but it seems logical to consider what's
connected to system and not just the system itself.
Tony -K2MO
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