EMI interference
 

Hello all,
I have recently installed my all wind and solar electric power system
and I am off the grid.
Here is the problem. My Trace ( Heart) inverter that supplies my AC creates
a lot of EMI noise on the AM band.
Any ideas of how I can shield the unit to stop this noise? The EMI noise is
present even when I run my Shortwave and AM on pure DC so it is not the AC
quality that is causing this problem. While on DC power if I switch the
inverter on the EMI starts and ceases when in shut the inverter off. Please
email me off list.

Thanks

C.M. Bereznoff wrote:
Hello all,
I have recently installed my all wind and solar electric power system
and I am off the grid.
Here is the problem. My Trace ( Heart) inverter that supplies my AC creates
a lot of EMI noise on the AM band.
Any ideas of how I can shield the unit to stop this noise? The EMI noise is
present even when I run my Shortwave and AM on pure DC so it is not the AC
quality that is causing this problem. While on DC power if I switch the
inverter on the EMI starts and ceases when in shut the inverter off. Please
email me off list.


That's impolite. In all probability, someone else has had the same
problem and could use help. I have the same problem with an inverter
in the garage. It's a 1750 watt (1500 watt in real life) Portawattz
which I've just replaced. It's a lot cheaper than your unit, so my
problems may not be caused by the same reasons as yours.

The modified sine wave is most likely a large part of the problem. It
should be more accurately called a 'modified SQUARE wave inverter'.
The internal switching circuitry makes radio noise.

I found that grounding the case of the unit to the negative side of
the battery helps somewhat. Plugging an extension cord in makes the
noise much more noticeable. The longer the cord, the more noise.

Can you feed the outlets with wiring in conduit?

One problem with SOME inverters is caused by trying to feed existing
wiring. A grounded neutral, like that found in most houses, will cause
inverter unit failure. I don't know if your model of Trace is affected
by that design problem. I'd be leery of connecting anything with a
floating neutral to wiring with a grounded neutral.

Check the complete threads here for possible means of filtering this
stuff. A pure sine wave unit may be your only solution. They cost more.

http://groups.google.ca/groups?q=emi...oogle+Sear ch


http://snipurl.com/ah46




mike

C.M. Bereznoff wrote:

Hello all,
I have recently installed my all wind and solar electric power system
and I am off the grid.
Here is the problem. My Trace ( Heart) inverter that supplies my AC creates
a lot of EMI noise on the AM band.


From a few years ago:

================================================== =
From: Eric F. Richards )
Subject: Does a 2500-watt inverter cause RFI or EMI in a SW radio?

View this article only
Newsgroups: rec.radio.shortwave
Date: 2000/05/25

(Dave) wrote:

Most inverters produce squarewaves, consisting of a fundamental
frequency and an infinite number of harmonics. As I recall.

Not that many anymore. Many produce a "modified sine wave"
which is really a square wave with a "step" at 0 with the lines
shorted -- helps motors run better -- but better choices exist.

Trace makes a "pure sine wave" inverter that really produces
what I call a "Mayan Temple Wave" with something like 38 steps
in it. I don't like it...

Both Statpower and Exeltech make high-efficiency (85%) true
sine-wave inverters. Exeltech is the brand I prefer... have
two... clean... but they also sell an add-on package in case
you still have noise, but I haven't needed it. I've put mine
on an o-scope to look at the waveforms -- perfect!


http://groups.google.ca/groups?hl=en...oogle%2BSearch


http://snipurl.com/ah48


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