HF inverters & interference [RE-wrenches]

[Doug Pratt]

Don't be in hurry to blame the HF inverter. How much interference you
see is greatly influenced by the quality of the filters on the
particular audio/video device. With the same HF inverter and different
TVs you may or may not get interference.
  I've got an Exeltech XP1100 that I use for emergency power backup. It
plugs into my EV battery pack, and the funky City of Ukiah power grid
has given me ample opportunities to try it out. (10 hours on
Thanksgiving afternoon/evening a couple years ago) It doesn't affect my
Sony TV at all.

Cheers,
Doug Pratt


-----Original Message-----
From: Todd Cory, Mt. Shasta Energy Services [mailto:toddcory at jps.net] 
Sent: Tuesday, July 16, 2002 4:16 PM
To: RE-wrenches at topica.com
Subject: Re: [RE-wrenches]

I have heard of similar problems with other Exeltech HF switching
inverters... I guess that is one big advantage of the trace boat anchor
approach using huge transformers. I am surprised that the tech did not
mention this interference is a common problem with their style of
inverter design.

I believe the only way to 'fix" it is to get another inverter. Live and
learn...

Todd



"David Palumbo, Independent Power & Light" wrote:

> We recently installed a small off grid 24v PV system utilizing an
Exeltech
> XP1100 sine wave inverter and an Iota DLS 24v 25 amp battery charger.
The
> system also has an Iota automatic generator transfer switch. The
system has
> 245 ahrs of battery storage and is grounded according to our standard
> procedures.
> It is installed in a small home that previously operated on gas lights
and a
> small generator (Honda 3k inverter gen) for TV, microwave etc.
>
> The television is picking up interference from our system. With the TV
> powered by the inverter it has some audible static and visual snow,
and
> diagonal lines that were not there when the Honda ran the TV all
alone. When
> the generator is run (without battery charger for now), and the
autotransfer
> switch loads the gen with the TV, the TV picture and sound are no
better
> until the inverter is actually shut off. At this point we are back to
the
> original TV picture and sound before our system was installed. When
the Iota
> battery charger is on the TV is at its worse state of picture and
> interference.
>
> The tech help at Exceltech suggested that the 6 foot run to the
inverter
> using #6 AWG cable (1% voltage drop at 1,000 watts)is too far, that
placing
> the inverter directly on top of the batteries would clear up the
problem.
> This we just can't do although we did twist the cables around each
other as
> also suggested. No relief. The inverter is seperated from the TV by a
wall
> and by a distance of 16'. The batteries are located in a battery box
in the
> same large room as the TV and are 14' away.
>
> The tech help at Iota offered that earlier models of the charger had
> interference issues but that these had been addressed in the newer
versions
> (we are told that we have a newer version as indicated by the blue
line
> under the Iota model number). It was suggested that a jumper wire be
added
> between the DC negative input to the charger and the ground terminal
> (creating a ground loop). Again, no relief.
>
> Any thoughts?
>
> Barry Shaw
> Independent Power & Light

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