[RE-wrenches] AM noise on batteryless inverters - Part 2

[Exeltech]

Part 2:

For greatest effectiveness, ferrite cores must be
installed on the DC and AC conductors as close to
the inverter as possible.

Capacitors installed across the AC conductors must
be of appropriate capacitance, voltage, and ratings
for this application, and must be UL-recognized for
such service.


RFI filtering is a bit like filtering of internal
combustion vehicle exhaust.  You can reduce the
unwanted/undesired aspects - but not eliminate them.



Dan



--- On Thu, 6/24/10, Exeltech <exeltech at yahoo.com> wrote:

> From: Exeltech <exeltech at yahoo.com>
> Subject: Re: [RE-wrenches] AM noise on batteryless inverters
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Thursday, June 24, 2010, 11:34 AM
> RFI (radio frequency interference)
> from inverters
> is a fact of life.  This is especially true at
> lower frequencies, such as for AM radio.
> 
> There isn't a cure-all.  Each make and model of
> inverter will differ in the amount of interference
> it generates.  Steps to reduce the problem also
> differ.
> 
> Ferrite cores (mentioned below) may help.  These
> need to be installed around DC and AC leads.
> Multiple cores on each DC leg are almost always
> required due to the very low impedance presented
> by the DC input side of the inverters.  Looping
> AC conductors multiple times through a large
> ferrite core will also be helpful.
>  
> Bypass capacitors are also often beneficial when
> they're connected to the conductors on the battery
> and load side of the ferrite cores.
> 
> Ensure all chassis screws are clean and tight.
> Earth grounding the inverter chassis may help.
> Experimenting will be needed with and w/o this
> ground to see which works better.
> 
> Separate the radio receiver from the inverter as
> far as possible.  Distance is your friend here.
> 
> Ham radio equipment tends to be less affected by
> inverter RFI because the receivers are fed with
> coaxial cable, which is self-shielding.  The coax
> is connected to antennas that are commonly 50-100'
> or more from the inverter.
> 
> There are some common steps you can try .. but in
> the end .. steps unique to the particular site
> may also be needed.
> 
> 
> Dan
> 
> 
> 
> --- On Thu, 6/17/10, Darryl Thayer <daryl_solar at yahoo.com>
> wrote:
> 
> > From: Darryl Thayer <daryl_solar at yahoo.com>
> > Subject: Re: [RE-wrenches] AM noise on batteryless
> inverters
> > To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> > Date: Thursday, June 17, 2010, 11:30 PM
> > I have heard that putting small ferrite donuts
> > around the AC and DC wires will reduce this
> > noise.  Place them inside the inverter.  they are
> > avaiable from DigiKey
> > Darryl
> > 
> > --- On Thu, 6/17/10, jay peltz wrote:
> > 
> > > From: jay peltz <jay at asis.com>
> > > Subject: AM noise on batteryless inverters
> > > To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> > > Date: Thursday, June 17, 2010, 8:35 PM
> > > HI All,
> > > 
> > > Say I've had a question from a client about AM
> radio
> > > noise from his battery-less inverter.
> > > 
> > > I'm wondering if there is any other folks out
> there
> > > who have found this to be problem?
> > >
> > > Now I realize that most people listen to AM in
> the
> > > evening when the  inverters are non-op so this
> > > might not be a problem for most people.
> > > 
> > > Thanks in advance,
> > > 
> > > jay
> > > peltz power
> 
> 
> 
>       
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