HF inverters & interference [RE-wrenches]

[William Miller]

I have an off grid client with a recording studio:

-Started with a Heart Interface inverter. Lots of noise.

-Moved to an SW4024.  Less noise.

-Tried a temporary connection to an Exletech 500.  No noise (we had to shut
off the Heart even though nothing was connected to it--noise was radiating
from the interior wiring).

-Client purchased a StatPower 1800, no noise.

Noise proclivity varied from electronic device to electronic device.  Most
susceptible were electric guitar pickups (passive devices, but effective
antennas).

William Miller


At 06:42 PM 7/16/02 -0700, you wrote:
>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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__________________________________________________________________
William Miller
Miller Power and Communications
PO Box 50, Santa Margarita, CA 93453
Voice :805-438-5600		Fax: 805-438-4607	VMail: 805-546-4875
email: wrmiller at slonet.org
http://millerpowerandcomm.com
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