Inverter Technology Cautions

10-15-2012, 04:20 PM

Inverter Technology Cautions
If you are a Ham or know one, there is an excellent article in this months issue of QST on some unknown things to be aware of using inverters or inverter generators. I will see if I can get permission to republish here.

**ShrimpBurrito** · 10-17-2012, 04:55 PM

The Nov issue? Which page? I skimmed through the Sept-Nov issues and didn't see anything pop out.

Dave

**ShrimpBurrito** · 10-17-2012, 07:53 PM

Found it!

10-18-2012, 07:41 PM

yup page 64.

countrygirl · 10-18-2012, 08:54 PM

Wow...their website is locked up tight.

I used to have a radio operators license many years ago...I don't think it would help me read the online issue though.

10-19-2012, 11:54 AM

Dying of curiosity here.

**ShrimpBurrito** · 10-19-2012, 02:19 PM

It's a fairly technical article.

My interpretation (and perhaps some EE's can chime in, as I am not): it is basically a letter to the editor that explains in detail why a GFCI outlet often trips using an inverter generator. Basically, GFCIs are intended to be used on a commercial power grid that has a grounded neutral. According to the article, inverters (that being power inverters, inverter generators, UPS's, etc.) output power where the neutral is not grounded -- in fact, there's little difference between the hot and neutral leads.

Apparently, the output of an inverter is less sinusoidal than grid power (I presume they are referring to pure sine wave units) -- due to the design of these units, there is inevitably some leakage current that is not canceled out because the switching of the hot and neutral leads are not in phase. The GFCI sees this as a problem, and trips as it's supposed to.

The article also says:

not to attempt to ground the neutral of an inverter without first consulting with the manufacturer, and it gives a technical explanation as to why.
that the neutral output of the inverter is likely hot
if you want to use a GFCI on an inverter, that you should first place an isolation transformer on the inverter output such that a safe grounded neutral can be established at the transformer output.

Dave

**Bill** · 10-19-2012, 03:51 PM

Bob -

If you would like to send a private copy to me (my email address is in my profile), I would be glad to take a look at it. I am a professional EE, so I would find it interesting, and might be able to prepare some comments in advance of your permission to release.

And Dave, based on what you have said, the author's comments and warnings are largely related to GFCIs. There is a lot of mis-information about GFCIs out there, and it sounds like he has his share. For instance, the coments about grounds and GFCIs is probably incorrect - GFCIs don't care about grounds, or their presence or absence. They care only about hot and neutral - and they care very much about these.

FWIW, I've used a Honda inverter generator on GFCI-protected circuits, with nary a peep. I think many of our members have done the same.

Just a thought.

Bill

10-19-2012, 04:43 PM

I feel better now, thank you.

WARNING: The following is not TM related. It's not even RV related. It may be tangentally related to this thread though.

This last weekend I used my Honda 2000 inverter generator to power a 120VAC to 240VAC transformer to run an inverter driven Mitsubishi 9kbtu split system heat pump.

Talk about a lot of invertin', convertin', and transforming. It worked great!

10-19-2012, 05:58 PM

Quote:

Originally Posted by Bill

Dave -

If you would like to send a privtae copy to me (my email address is in my profile), I would be glad to take a look at it. I am a professional EE, so I would find it interesting, and might be able to prepare some comments in advance of your permission to release.

Based on what you have said, the author's comments and warnings are largely related to GFCIs. There is a lot of mis-information about GFCIs out there, and it sounds like he has his share. For instance, the coments about grounds and GFCIs is probably incorrect - GFCIs don't care about grounds, or their presence or absence. They care only about hot and neutral - and they care very much about these.

FWIW, I've used a Honda inverter generator on GFCI-protected circuits, with nary a peep. I think many of our members have done the same.

Just a thought.

Bill

Thinktwo things are appropriate: A GFCI will work, but will be difficult to reset when connected to an invertor and that the common side of AC from an invertor can have 65VAC on it.