On 5 Oct 2006 22:00:52 -0700, "gaffcat" wrote:

I use a Honda 2000 watt inverter generator on my boat to occaisionally
charge batteries. The boat stays on a mooring so I have no access to
shore power.The generator hooks up to the boats shore power plug and AC
panel then to an AC charger. The panel has a reverse polarity light and
it lights up indicationg reverse polarity when I run the generator.
With no load on the AC panel I can reverse the positive and neutral
wires and still get the reverse polarity light. When I test the output
of the generator, at the generator, I get 120 volts with the positive
and negative but I also get 40 to 70 volts when I test the neutral and
ground. I called the Honda dealer where I bought the generator and they
said they had no idea why that would be happening. The generator powers
tools or any other load without a problem. Does anyone have any idea
what might be going on? When I was building the boat in my yard there
was never any problem connecting to regular AC through the same system.

fritz

Many small inverters (perhaps some big ones, too) have a "floating
neutral" - during one half-cycle, the neutral will be about +170 V,
and line will be 0. During the other half-cycle, line will be +170,
and neutral 0. This simplifies the inverter output circuit as it
means that a -170V source is not needed to produce the negative
half-cycle. (170 V is the peak voltage of a 120V sine wave.)

Since the Honda generator uses an inverter technology, I wouldn't be
surprised to find that it does the same.

This should not cause any problems (other than confusing your polarity
indicator), as power is always taken between line and neutral, without
reference to ground.


--
Peter Bennett, VE7CEI
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