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Mr. Luddite

On 11/19/2014 3:33 PM, wrote:
On Wed, 19 Nov 2014 14:52:17 -0500, "Mr. Luddite"
wrote:

On 11/19/2014 2:17 PM, wrote:
On Wed, 19 Nov 2014 06:33:38 -0500, "Mr. Luddite"
wrote:

I agree with all you said but switching power supplies have an
additional issue with ground fault detectors, due to their design and
how they function. Not so much with smaller battery chargers but
anything that draws significant current (like an RV or Boat
inverter/charger system) usually trips it. I've had problems with
three different RV's. Works fine on a non-GFI circuit.

I know of nothing in a switcher that should trip a GFCI and I have a
couple of PCs that run just fine on the GFCIs. Current may lag voltage
but Dr Kirchoff says the current in will equal the current out at any
given instant and that is what a GFCI compares.
AFCIs are different, they actually look at current "signatures" and
those spiky switching power supplies can trick one.
I bet your charger has regrounded the neutral, probably through an RF
filter. That is usually the culprit.
Wayne has the answer, A transformer. If the noise is not an issue to
you, disconnecting the filter is always an option or just couple it to
ground through a capacitor..

Low current devices like a PC usually are not a problem although
nuisance tripping has been reported. Higher current draw devices (like
an RV inverter/charger have more issues.

There's nothing wrong with the inverter/charger or the GFI. It's a
reflected component of the high frequency power supply induced into the
power source line that confuses the GFI. Not an issue unique to my
experience. You can find discussions on it elsewhere.

Wayne's transformer recommendation works just fine. I ended up having
to use a Hughes Autoformer for the RV's in Florida because the voltage
where we were often drooped significantly during parts of the day. I
measured as low as 105 vac at times. As an experiment, I tried using
the Autoformer back up in MA on the GFI circuit and everything worked fine.

You are not getting much isolation with an autotransformer. The
primary and secondary are tied together.
It still might solve the problem thought because the connection is on
one if the circuit conductors so the differential toroid in the GFCI
sees the current as being balanced
I still say if you are tripping a GFCI, it is because there is a
circuit from the line conductors and ground, usually a RF suppressor.
It will be designed to pass more if you have a higher current
switcher.
I know there is plenty of "discussion" and plenty of theories but the
guys who actually design them have the opinion I trust.

Isolation transformers are effective in quenching noise (and in some
cases arcs) that can be induced either in the supply side or by the item
being powered. Basically acts as a big choke.

Ever notice what's missing in high frequency switching power supplies?
Big, heavy, iron core transformers.

Switchers are great but they can be noisy.