I spotted the close proximity of the input 3-phase power and power to the
compressor right off the bat as did you. Your other approaches are
certainly good, excellent, with the possible exception of composition of
the ferrite (or powdered iron) cores.
All these cores are common mode chokes. I can not judge on the
effectiveness as such based on the (few) number of turns through each
toroid. Here is the color coding for cores from Amidon:
http://www.qrz.lt/ly1gp/amidon.html
The tan core is phenolic and offers nothing in terms of inductance
enhancement (µr) due to the presence of the toroid. These are all powdered
iron of one form or another and are not intended to do much as a common
mode choke or EMI suppression. If that was the reason for their choice by
Rheem, they chose the wrong core materials for the cores. Good
intentions.......bad execution. They are more suited for hi-Q inductors
over their target frequency ranges. I'd advise you leave those alone as
they may be doing something "unknown" to the casual observer regarding
performance of the unit. However, I'd also advise augmenting each winding
with common mode chokes (all three wires through a common core for each
with nominally three passes through the each core) wound on 31 material
which is excellent for the CMC application. Those included chokes do
little for EMI suppression. CMCs would on 31 material should be much
better at suppressing EMI than the included toroidal chokes.
Current rating of the proposed Corcom 3-phase filter: Be sure the filter
will take the starting current draw on the compressor.
Dave - WØLEV
On Sun, Oct 3, 2021 at 5:00 PM Karin Johnson <karinann@tampabay.rr.com>
wrote:
> Hello fellow RFI'ers:
> Some time ago (probably over a year ago)I posted about RFI/EMI from a Rheem
> HVAC unit, Model RP1748AJVCA. I've been very busy with other projects.
> Life
> gets in the way sometimes.
> Anyway, I've recently decided to tackle this issue again. And am doing some
> more investigation. I can't definitively say that the RFI/EMI is coming
> from the 240 volt power wiring but in my investigation I've come across a
> couple of clues that this may be the main source of the issue. I'll
> describe some more comments after the below links.
>
> The first link is JPG of area around the 240 volt line input to the outside
> condenser unit.
>
>
> https://drive.google.com/file/d/1LulAakSfuktJbvGiRrQwPHTWSCRSziJK/view?usp=s
> haring
>
> The second link is a annotated Power Point of the same JPG, showing 240
> line
> input and 3 phase wiring to the Copeland 3 phase compressor.
>
>
> https://docs.google.com/presentation/d/1Dp5RemNEcXDJrCTd94i9J5FkX-a--3-l/edi
> t?usp=sharing&ouid=101983102297392238928&rtpof=true&sd=true
> <https://docs.google.com/presentation/d/1Dp5RemNEcXDJrCTd94i9J5FkX-a--3-l/edit?usp=sharing&ouid=101983102297392238928&rtpof=true&sd=true>
>
> I would like to get some comments from the group about how the 240 line
> input is routed very close to the 3 phase output from the inverter.
> Notice that there are two toroids, one colored tan(3 phase inverter
> output),
> the other colored green(240 volt line input) that are very close to each
> other. I am thinking that because of the closeness of the two toroids
> there
> is probably some coupling of 3 phase power signals to the 240 line input.
> Also I've been looking at some of the documentation from Rheem about the
> design and operation of the outside condenser unit with the 3 phase
> inverter.
> Here is some of the wording of the document when describing the filtering.
>
> For the (-)P17 model line there are 3 ferrite
> rings and one filter applied on all models. The
> ferrite rings are similar in purpose to the choke,
> whereas they create an inductive field around
> the assembled wires, but they do not filter the
> signals. The ferrite rings are applied only for the
> purpose of keeping the high voltage lines from
> cross contaminating one another and thereby
> creating unexpected operation and Electro
> Magnetic Interference. The single filter has been
> applied to eliminate high frequency "noise" from
> the incoming power line thereby making it more
> efficient for the inverter to convert the incoming
> high voltage single phase AC power into high
> voltage 3 phase DC power.
>
> What is interesting about that paragraph is that the filters and toroids
> are
> meant to keep EMI ingress from entering the unit, NOT keep the EMI inside
> the unit.
>
> I have it in mind to add a 36 amp Corcom line filter to the 240 line input
> in an external enclosure bonded to the metal enclosure of the outside unit.
> I am also considering moving the internal filter board of the unit to the
> external enclosure and re-routing the 240 wiring to keep it away from the 3
> phase inverter power. Most likely placing it on the left side of the
> enclosure as shown in the pictures. I might also change out the tan and
> green toroids for type 31 devices. I can shut down the entire unit and
> remove the existing toroids to measure them, before doing this.
>
> Thanks for looking.
>
> Karin Anne Johnson P.E. K3UU
> Palm Harbor, FL
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
--
*Dave - WØLEV*
*Just Let Darwin Work*
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