Re: Scary Tingling


"Jim" <jiminfl@xxxxxxxxxxxxx> wrote in message
news:%QoLg.6682$xQ1.728@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


OK. I got a little caried away. I guess that some really bodacious filter
caps in the TV power supply could take long enough to charge up to alert
the GFI circuits to a current imbalance. What was causing the Xantrex
problem? The timing of the transfer relays?

The Xantrex problem was in the microprocessor section. The power supply and
transfer switch operation was fine. It just started reporting every possible
fault condition that the unit was programmed for .... high volts, low volts,
low battery volts, high battery volts, high battery temp, low battery temp
(even though the temperature sensor was not even installed). It also
decided to start charging the house batteries at a "custom battery" setting
of 15.5 volts, although it was programmed for the regular lead acid setting.
The problem was that every time it defaulted to a bogus fault condition, we
lost all 120 volt power and the battery charger. I finally by-passed it
completely and used another charger for the batteries. That's the way it
was when we traded it the Chinook in a year later. I never had any power
problems without it, although obviously we had to go without the 2000 watt
12vdc to 120vac inverter section. No big deal because we never used it
anyway. Marty's had it replaced or repaired under warranty.

As to GFIs ...


I don't think linear (the old fashioned transformer, full wave bridge
rectifier and bodacious filter caps) cause a GFI any grief.

It's the switched mode (switching power supply) supplies that can cause a
problem because the line voltage coming into the device is directly
rectified and filtered without benefit of any heavy transformer to isolate
it. Plug in any device that has a switching power supply that was left in
the "on" position and witness the arc it draws from the outlet to the plug
for a brief moment. It looks like a short circuit ... because it is, for
about half a cycle and it generates a transient spike that momentarily
upsets the current relationship between neutral and hot in the GFI.
That's the problem that a GFI doesn't like. There is nothing wrong with the
supply or design of the supply. It's operation is just not always
compatible with the fast reacting and sensitive GFI.

Here's a schematic of a switching power supply design. Check out how the
line voltage (220v in this case) is rectified:

http://ludens.cl/Electron/PS40/Figure1.gif

Theory of operation and circuit description at:

http://ludens.cl/Electron/PS40/PS40.html


Not all, but many modern converters, inverters and battery chargers are now
built with switching power supplies to reduce weight, heat and increase
efficiency. I know from experience that it is the reason some people are
experiencing problems getting powered up when connecting to GFI protected
services. Usually though, if you keep resetting the GFI, the power supply
will charge up enough to stop tripping it .... until the next time you try
to hook up.


Eisboch


.

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