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<p><i>"</i><i>Is there any inherent advantage or disadvantage to non
transformer inverters? </i></p>
<i>
</i>
<div dir="ltr"><i> </i><i>Jay"</i></div>
<div dir="ltr"><br>
</div>
<p>Well, non-isolated transformer-less inverters have their own
problems that can make common-mode EMI worse actually than
isolated.</p>
<p>There are special (and patented) design techniques to reduce this
and some non-patented ones that work similarly. I think SMA is one</p>
<p>with a patent on it. It has to do with how the output stage of
the inverter does its shorting of the full-bridge in-between high
and low</p>
<p>PWM pulses. Interesting stuff.</p>
<p>But engineering is always a compromise. Audio electronic
engineering was MUCH easier than power electronics IMO.<br>
</p>
<p>boB<br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 10/3/2020 8:01 AM, Dave Angelini
Offgrid Solar wrote:<br>
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cite="mid:20f1a92913b969100736d2d4b6fcb838@127.0.0.1">
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<p>I would think if the devices meet the tested Class B spec then
no advantage. Engineers can design filters for the Class B
requirement. The radiated RF may be different between two
identical specced inverters of different topology. Even that can
be designed in, if there is a requirement and it is tested for.</p>
<p>The basic test anyone can do is with a 10 dollar analog AM
radio tuned to a weak station. If you can't get 5 feet back from
the inverter and hear the station, then you have work to do to
suppress the radiated garbage. An XW is about 3 feet if it is
installed correctly. My truck inverter which is transformerless,
will kill AM for about 50 feet.</p>
<p>See what Bob says, my component level engineering is from the
1980's and dated.</p>
<div>
<pre> </pre>
<pre><strong><span style="font-size: small;">Dave Angelini Offgrid Solar
"we go where powerlines don't"
<a href="http://members.sti.net/offgridsolar/" target="_blank" moz-do-not-send="true">http://members.sti.net/offgridsolar/</a>
e-mail <a href="mailto:offgridsolar@sti.net" moz-do-not-send="true">offgridsolar@sti.net</a>
text 209 813 0060</span></strong></pre>
</div>
<p>On Fri, 2 Oct 2020 11:58:15 -0600, Jay
<a class="moz-txt-link-rfc2396E" href="mailto:jay.peltz@gmail.com"><jay.peltz@gmail.com></a> wrote:</p>
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<div dir="ltr">Hi Bob</div>
<div dir="ltr"> </div>
<div dir="ltr">Is there any inherent advantage or disadvantage
to non transformer inverters? </div>
<div dir="ltr"> </div>
<div dir="ltr">Jay</div>
<div dir="ltr"><br>
<blockquote type="cite" style="padding-left:5px;
border-left:#1010ff 2px solid; margin-left:5px; width:100%">On
Oct 2, 2020, at 11:27 AM, <a class="moz-txt-link-rfc2396E" href="mailto:bob@midnitesolar.com">"bob@midnitesolar.com"</a>
<a class="moz-txt-link-rfc2396E" href="mailto:bob@midnitesolar.com"><bob@midnitesolar.com></a> wrote:<br>
<br>
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border-left:#1010ff 2px solid; margin-left:5px; width:100%">
<div dir="ltr">
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<p> </p>
<p>This is all great advice.</p>
<p>Remember that long wires can radiate RF. PV lines and
the array can make a good antenna for RFI as well as the
battery lines.</p>
<p>I agree with Dave that both of those inverters are more
than likely similar. I know that the XW has a good filter
on the battery line</p>
<p>right where it should be, at the exit point.</p>
<p>An additional ferrite toroid core used in common-mode
filter hookup (BOTH hot and cold wires run through the
center) as close to</p>
<p>the unit as possible on AC and DC wires as well as
possibly, communications lines exiting the units. Battery
temperature sense also,</p>
<p>possibly.</p>
<p>As for resources, Palomar link that Roy gave is a good
resource. Digikey or Mouser might also be a good place to
look for both the</p>
<p>parts themselves and possibly information.</p>
<p>boB<br>
K7IQ</p>
<p> </p>
<div class="moz-cite-prefix">On 10/2/2020 8:57 AM, Dave
Angelini Offgrid Solar wrote:</div>
<blockquote type="cite" style="padding-left:5px;
border-left:#1010ff 2px solid; margin-left:5px;
width:100%"><!-- meta ignored -->
<p>My advice is it is more about the installation and the
distance from the inverter, and it's devices from the
station location, than the make of equipment. There are
other things also that I do to fix noise and
interference. My wife is an extra class operator and
several clients have visited to get ideas. Most any
noise issue can be fixed later, unless you are too close
to the source.</p>
<p>That said I mainly use XW and I would assume Radian is
similar. Below is the spec that XW is test for and has
been since 2005.</p>
<p>" EMC directive FCC and Industry Canada Class B " Below
are 2 of the ways that the issue is defined and
measured.</p>
<p><span>So-called "</span><strong>radiated emissions</strong><span>"
are picked-up </span><strong>with a</strong><span> test-antenna
and can come from all parts of the product INCLUDING
the cables it uses (power and module interconnects). </span><strong>Conducted
emissions</strong><span> are measured directly as
voltages or currents on the cables used by the
product.</span></p>
<div>
<pre> </pre>
<pre><strong><span style="font-size: small;">Dave Angelini Offgrid Solar
"we go where powerlines don't"
<a href="http://members.sti.net/offgridsolar/" moz-do-not-send="true">http://members.sti.net/offgridsolar/</a>
e-mail <a href="mailto:offgridsolar@sti.net" moz-do-not-send="true">offgridsolar@sti.net</a>
text 209 813 0060</span></strong></pre>
</div>
<p>On Fri, 2 Oct 2020 09:35:34 -0600, Mac Lewis <a
class="moz-txt-link-rfc2396E"
href="mailto:maclewis1@gmail.com"
moz-do-not-send="true"><maclewis1@gmail.com></a>
wrote:</p>
<blockquote style="padding-left: 5px; border-left: #1010ff
2px solid; margin-left: 5px; width: 100%;">
<div dir="ltr">Hi Wrenches,
<div> </div>
<div>I have a HAM radio enthusiast that needs to
replace their off-grid inverter. He would like the
inverter that puts off the least interference. I
don't know a whole lot about evaluating an inverter
for this, but I am reaching out for
recommendations. Needing ~8kVa at 48V.</div>
<div> </div>
<div>Thanks!</div>
<div> </div>
<div><br clear="all">
<div> </div>
-- <br>
<div class="gmail_signature" dir="ltr">
<div> </div>
<div><span style="color: #305a78; font-family:
'times new roman', serif;"> </span></div>
<div> </div>
Mac Lewis<br>
<br>
<p align="left"><span style="color: #000000;
font-family: Verdana, Arial, Helvetica,
sans-serif;"><span style="font-size: small;"><span
style="font-family: arial; font-weight:
normal; color: #305a78;"><span
style="font-family: 'times new roman',
serif;">"Yo solo sé que no sé nada." </span><span
style="font-weight: bold; color:
#686868;"><span style="font-family:
'times new roman', serif;">-Sócrates</span></span></span></span></span></p>
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