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<p>My understanding is anything over 5% THD is getting to be a
problem. I've measured that high on grid here before. Do you
have any idea what harmonics this distortion is at? Have you
looked at it on an O scope? What generator is this? I've seen
portable generators with terrible wave forms under load. They
have a front end spike on the waveform, and then they flatten out
under load. Anything that isn't a pure sine wave is distortion.
<br>
</p>
<p>Have you checked the peak of the wave form? I've seen generators
under load, flatten to 135 v peak, which is really not even a sine
wave anymore. Very poor performance, most AC electronics do not
like a DCish wave form. <br>
</p>
<p>Also, I have a Seaward meter that does THD, its a little clunky
to navigate, but it gives real time readings, is battery powered,
and can break out the separate harmonics too. The harmonics just
give you an idea at what frequency the distortion is at, which
"might" let you figure out what is causing problems. I don't know
enough about AC GFI electronics to know what effect THD would
have, but 19% THD is total trash, and all bets are off; it could
damage all sorts of other equipment too. <br>
</p>
<p>I think you've already done all that needs to be done: They need
a better generator.<br>
</p>
<pre class="moz-signature" cols="72">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="moz-cite-prefix">On 1/23/20 1:16 PM, William Miller
wrote:<br>
</div>
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<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Colleagues:</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">In
a recent post about some AC GFI tripping problems, I
mentioned I am measuring some high THD readings in certain
scenarios\u2014the highest being when the generator is charging
at high percentages:</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Inverter
only: 2.5% THD</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Gen
Max: 19% THD</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Gen
5 Amps: 8% THD</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">I
measured the THD using a Fluke <a href="TJ3fTpspG2DGCzC"
moz-do-not-send="true">VR1710</a>. This is a handy little
gizmo and pretty expensive considering its size. The device
has limitations:</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">1.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">It
is cord connected.</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">2.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Results
cannot be viewed in real-time.</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">3.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">It
measures voltage parameters only.</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Here
are my questions:</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">1.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Has
anyone here had to consider problems with high THD in any
off-grid scenarios?</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">2.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">What
readings are normal?</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">3.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">What
is the significance of voltage harmonics versus current
harmonics?</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">4.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">What
instruments are you using to measure THD?</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">5.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Has
anyone seen high THD causing AC GFI tripping?</span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""><span
style="mso-list:Ignore">6.<span style="font:7.0pt
"Times New Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">What
other symptoms might occur with high THD?</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Tip:
The reason we first started suspecting high THD is that
cheap voltmeters registered abnormally high (including the
onboard Radian metering) during periods of high THD, while
true RMS meters (Fluke 87) continued to measure normal AC
voltages. If you experience this situation, high THD is
suspect.</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Answers
are always gratefully appreciated.</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">William
Miller</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">PS:
If you are receiving a BCC of this email, it is because you
are part of the team working on this problem. The message
is directed to an industry forum in hopes of gleaning
additional knowledge. I will share any results I receive.</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Wm</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif"">Miller
Solar</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif"">17395
Oak Road, Atascadero, CA 93422</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif"">805-438-5600</span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif""><a
href="http://www.millersolar.com/" moz-do-not-send="true">www.millersolar.com</a></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif"">CA
Lic. 773985</span></p>
<p class="MsoNormal"> </p>
</div>
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