[RE-wrenches] Inverter causing migraine?

[boB Gudgel]

Dan Fink said:

"That's a tricky situation. There are only two possibilities for what's 
causing the problem; sound or electromagnetic radiation"

I'm betting that it's sound.  Remember how you could hear televisions 
singing
away at 15 kHz ??  That still gives some people headaches.

How old is this customer ??   I'm guessing he's young because it's most 
likely because he
can hear the inverter switching.    We just can't normally hear 
them....  The FX/VFX
inverters switch at around 20 kHz which some people can still hear.  
Especially younger ones
with better hearing.

It's probably the transformer windings and iron acting as a 
speaker/transducer.

High frequencies are very directional so will usually respond well to a 
thin wall  of
padding between inverter and the rest of the inside of the house or cabin.
That should help reduce the acoustical output.

boB






Dan Fink wrote:
> Joel --
> Good points. In a recent newspaper article in Boulder, CO about a 
> really bad PV install, the direct grid tie inverter was mounted right 
> on the outside of the wall from the homeowner's bed. They finally had 
> to have it moved--mostly because of buzzing, but EMF was a concern 
> too. It was basically less than a foot from the guy's pillow.
>
> Also, I forgot to mention that there are fairly inexpensive EMF meters 
> available from the same places that sell DIY shielding materials.
>
> The biggest source of EMF at *my* house is actually the E-Meter 
> measuring amp-hours. It even interferes with my handheld ham and fire 
> department radio FM communications on 2 meter.
>
> DAN FINK
> Renewable Energy Consultant
>
>
>
>
> Joel Davidson wrote:
>> Ron,
>>
>> Electromagnetic fields are produced any time you have current flowing 
>> through wire. They are low frequency waves that drop off rapidly 
>> proportional to the distance from the source. Inverters, 
>> transformers, fluorescent light ballasts, motors, clock radios, power 
>> blocks, microwave ovens, kilowatt hour meters, service panels all 
>> emit EMF. There is no
>> practical way to block EMF.  It passes through almost everything 
>> including walls and even lead. There is no U.S. safety standard for 
>> EMF. Some say 8 milligauss or more is dangerous and 2.5 milligauss or 
>> less is safe.
>>
>> I went through our home about 10 years ago using a borrowed 
>> milligauss meter (thanks David Katz). Our utility meter service had 
>> significant EMF, but that was not a problem since it is mounted on an 
>> outside wall and there is a closet between the living space and the 
>> meter. The EMF had fallen to below 2 milligauss between the wall and 
>> the closet door. The bedroom clock radio was the second largest EMF 
>> source in our home. Moving the clock 1 foot away from the bed to the 
>> other side of the night stand brought the EMF levels under 2 
>> milligauss. Our SW4048 inverter emitted a field that fell to a safe 
>> level 2 feet from the inverter.
>>
>> I tell people not to put their bed against the wall where their 
>> utility service panel or inverter is mounted. I also tell them that 
>> the Japanese did a 2 year study of school children riding the Tokyo 
>> subway (big EMF emitter) and found that there was no danger.
>>
>> Some sounds that most of us take for granted can cause physical 
>> discomfort and even pain. SW4048 and other transformer and electrical 
>> and electronic buzzing can be annoying. Also certain wavelengths and 
>> intensities of light can cause pain and injury.
>>
>> Joel Davidson
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