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Re: [RFI] RFI & Washing Machines

To: Dale Svetanoff <svetanoff@earthlink.net>
Subject: Re: [RFI] RFI & Washing Machines
From: "Christopher E. Brown" <cbrown@woods.net>
Date: Sun, 6 Sep 2009 16:09:28 -0500 (CDT)
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On Sun, 6 Sep 2009, Dale Svetanoff wrote:

> Great job!  Thanks for posting both your efforts and results -  very
> useful.  One question:  where did you buy the Corcom filter and can you
> give us the model or part number?  I was unaware that Corcom was now making
> a filter specifically for VFDs.
> 73, Dale

First note:  This will void the warranty, more more important, this is a 
home appliance...  It may only be 120Vac, but is likely sitting in a 
general use area w/ family/kids/etc.  If there is any doubt that you are 
fully qualified to do the work, grab an expert...

Also, these filters go at the AC *input* _NOT_ in between the motor drive 
and the motor.  Putting it in front of the motor can damage the controller 
and/or iverheat the filter (as well as generally breaking the washer).

In my case, the controller to motor cabling is short (< 12 inches) with 
an all steel case, while I could hear the washer on all HF bands it was 
not nearly as bad as some of the other I sampled with partially plastic 
cases and/or long motor cable runs.

I didn't see a "this is for VFD" class of filter, but some of the filter 
lines are noted for use in motor drives, and digging through app notes 
mentiones it.

I used an EMC series filter, the brag sheet says

The EMC series is the most compact dual stage filter available from Tyco 
Electronics. This cost effective design has a maximum current rating of 30 
amps; higher than any similar catalog product. The EMC series was designed 
to address the need for more differential mode attenuation in the lower 
frequency range while still maintaining high common mode performance. This 
type of performance is typically needed for motor drives and switch mode 
power supplies with increased operating frequencies. The EMC series is 
ideal for applications that require a high level of performance in a 
compact, cost effective package.

I picked up 10 10EMC3 from Mouser (Mouser P/N 592-10EMC3) for about 18$ 
each last year.

I picked them because of the motor note and the listed LISN 50ohm atten 

Line to gnd at 1,2,10,20,30mhz as 72,72,56,50,48db

Line to line at 1,2,10,20,30mhz as 54,58,47,34,36db

The 10EMC3 is a tab mount with leads.

I also used a pair of 30EMC6 filters (tab mount screw-post), on a 3000VA 
UPS (one on input and one on output) to good effect.

I would suggest spending time looking through the corcom site, they 
publish loss tables per the LISN spec for all units.  I went through the 
site, and then went searching for the better looking parts at 
mouser/digi-key/etc for pricing.

The 10EMC3 looked like the best bang/buck for general use at 10amp, the 3 
and 6 amp versions have better line to line, but worse line to gnd.

I was going to pickup a batch of 3EMC3 units as well (59db or better 
common mode 1-30Mhz), for general lighting/etc use but they were still 
about $14 each at Mouser so I decided to wait untill I needed them.
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