[RE-wrenches] THD problem solved

[William Miller]

Friends:



I was whining on this forum recently about an off-grid system
<https://millersolar.com/MillerSolar/Portfolio/Inverters/battery_iinverters/JP_Radian/JP_Radian.html>
that was tripping GFI and AFCI breakers and devices.



The problem seemed to be related to high THD on the voltage waveform
experienced when the generator was charging the batteries.  We first
discovered this THD problem when inexpensive AC voltmeters disagreed with
True-RMS AC voltmeters.  Subsequent testing with Power Quality Monitors
indicated 28% THD of the voltage waveform.



Well it turns out that when these three-stack Radian inverters were set for
Generator AC input mode, the charger circuits generated a lot of THD (28%f
in our case).  However, when we selected Backup, Support or UPS mode the
THD went down to 3.5%f.



For those of you that have had various appliances that perform poorly with
a given inverter, you might check to see if the failures coincide with
generator run.  It could be that it is the charging circuit that is the
culprit and not the inverting circuit.  Knowing this could be helpful.

I hope this information may prevent one or more of you from tearing out
hair.  For a full report of our travails, see this link
<https://millersolar.com/MillerSolar/case_studies/25_GFI%20Tripping/GFI_Tripping.html>
.



William



PS:  It has only been a few days since we adjusted the settings, but so far
no more tripping.



WM



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985
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