[RFI] RFI Digest, Vol 241, Issue 21

[Jamie WW3S]

Funny all this talk of variable frequency drives, etc, and this comes in 
today mail......I got a letter from our local electric co-op, 
introducing their new engineering manager, and enclosed was a copy of 
their power quality policy. I've attached the relevant pages about VF 
drives/motors.


------ Original Message ------
>From "Kenneth Wyatt via RFI" <rfi at contesting.com>
To rfi at contesting.com
Date 2/14/2023 3:20:26 PM
Subject Re: [RFI] RFI Digest, Vol 241, Issue 21

>Steve is correct that it’s possible to purchase large appliances that are designed with EMC in mind (mostly for the European market). As an EMC consultant for the past 15 years, I’ve helped several appliance clients with their washing machines, air conditioning systems, etc. achieve EMI compliance. The problems I’ve seen include EMI mains filters located too far inside the works, which allows noise coupling directly into the mains wiring. Also the VS drive electronics is not fully enclosed with shielding. But the biggest problem is that the internal cable routing is haphazard, allowing multiple coupling between noisy circuits and mains wiring, which can lead to both radiated and conducted emissions.
>
>I, and a handful of others, in the world also teach product design for compliance to EMC and product safety, but these topics are largely ignored in college and university. The result is that designers end up learning the hard way about EMC and the end users bear the consequences.
>
>Kenneth Wyatt
>Woodland Park, CO
>Sent from my iPhone.
>
>>  On Feb 14, 2023, at 12:38, rfi-request at contesting.com wrote:
>>
>>  From: Steve Dyer W1SRD <w1srd at yahoo.com>
>>  To: rfi at contesting.com
>>  Subject: Re: [RFI] Fwd: RFI Digest, Vol 241, Issue 20
>>  Message-ID: <ae833fd3-d6fb-7f0e-e8f2-8c7daf065431 at yahoo.com>
>>  Content-Type: text/plain; charset=UTF-8; format=flowed
>>
>>  Steve,
>>  I guess you don't believe and want some evidence.
>>  I have the Bryant Evolution Extreme (equivalent system to the Carrier
>>  Infinity Greenspeed) and it is RF quiet. It was one of the conditions of
>>  purchase I made with the installer. Both the air handler and compressor
>>  are VS.
>>  This is a 2013 vintage system so I have a few thousand hours in front of
>>  the radio with the system on and off.
>>  I live in a rural location so it's not masked by local noise. The beams
>>  are within 100'.
>>  I can stand right next to the outdoor unit with a SW radio and barely
>>  hear anything.
>>  I am extremely pleased with the systems lack of RFI, efficiency and home
>>  comfort.
>>  Variable speed systems can be engineered well for EMC.
>>  73,
>>  Steve
>>  W1SRD
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