Karin, it sounds like you know what to do and have the equipment to
measure results. Just a caution from EMC/RFI experience: Many active,
SMPS's and converters, do not tolerate complex loads or sources. The
Corcom will present a complex source impedance to the whole unit. Be sure
all the active 'converters' can handle that source impedance. Installation
of the filter may also 'confuse' the PFC, if it is active, as well. You
commented it is a simple inductor which may not be a problem, but might not
be as effective looking into a complex source. Mostly, just thinking out
loud.
Dave - WØLEV
On Tue, Oct 27, 2020 at 11:28 PM Karin Johnson <karinann@tampabay.rr.com>
wrote:
> I received a reply from Don Kirk, WD8DSB and Dave Eckhardt W0LEV.
> First off a big thank you for both replies. I do have a commercial
> Power line filter, which I did not mention in the Power Point documents
> because I wasn't trying to propose solutions just yet. My main point
> For the documents was to post my initial observations about the wiring
> installation.
> Now having said that. The power line filter I have is a Corcom model
> 16FC10. It has some pretty impressive attenuation data associated with
> It. I have also confirmed the attenuation data, by actually measuring
> It with my HP8753C vector network analyzer. The measurements were taken
> In a 50 system using two DX engineering 1 to 1 baluns. I have calibrated
> The system with the baluns so I can measure both common mode and
> differential mode attenuation. It agrees very closely with the data sheet
> For the Corcom 16FC10 line filter.
>
> Now to the toroids shown in the documents. As far as I can tell these
> toroids are not the typical ferrite toroids you might find in RFI
> applications. They appear to be "TAPE WOUND" type toroids. I haven't
> found
> a lot of information regarding using Tape Wound toroids for HF RFI/EMI. In
> fact most of the information I have found only addresses the use of such
> toroids with very low frequency (ie: less than 100 kHz) applications. I
> don't know if I can get hold of a filter board outside of the unit
> installed
> in the outside compressor, but if I can I plan to measure its
> characteristics. Heck, even if I can't get another filter board, I could
> plan on just shutting down the entire system, pull the safety
> Interlocks for the 240V and remove the filter and toroids and measure what
> is installed. I know that is going to be a bit drastic, and I am
> definitely
> not looking forward to that task.
>
> Now with respect to saturation of toroids. I have some partial good news
> with respect to the AC current being drawn by the Power Inverter board and
> the Copeland 3 phase compressor. I have an energy monitoring system on my
> home made by a company in Cambridge, MA called SENSE. I have an individual
> Current transformer on the dedicated supply line feeding the outside
> compressor unit. The SENSE system tells me that the maximum current at 240
> volts is only about 6.25 amps. The system has been running in cooling mode
> only so far in Florida here. I haven't put the system into heating mode.
> It is a Heat Pump. I suspect that in heating mode the current draw might
> be
> higher but I don't know what specific value might be expected. This is
> important because the Corcom power line filter I have has a current rating
> of 16 amps at 240 Volt AC. Obviously if a ferrite type toroid were to be
> also inserted into the 240 power source wiring, then I would have to know
> if
> the ferrite toroid would have to be "doubled up" (ie: using multiple
> stacked
> Cores). I do have a couple of Fair Rite snap on cores of type 31 mix. They
> are the biggest that Fair Rite makes.
>
> Current Probes
> Yes I have a couple of Tektronix current probe kits that I can use to
> actually put on the 240V supply line and the thermostat wiring. I also
> have
> Access to a set of the HP CLOSE FIELD probes. Eventually I will get to
> doing work necessary to probe with test equipment. The only reason I have
> Yet to do this is several. 1 - Dragging my Tek7000 series scope outside is
> a bit of a chore. 2 - It is still quite warm in Florida, and working
> outside
> In the heat right now, is, well uncomfortable. I am in no particular rush
> to get this solved immediately. I prefer to take a slow and measured
> approach to solving these things. 3 - The installer contractor is going to
> replace the unshielded thermostat wiring with shielded wiring at no cost to
> me.
> So I want to wait a bit to see how the shielded wiring affects things,
>
> With regard to filtering every wire. Yes that should be the plan. I do
> have a major addition planned with respect to adding another shielded
> enclosure to the power and control wiring inputs to the compressor. It
> would be installed and bonded to the chassis of the outside unit. I would
> Remove and relocate the Rheem filter and toroids to the extra shielded
> enclosure, plus add the Corcom filter to the 240V supply leads. If it
> turns
> out that the thermostat wiring is a major contributor then either massive
> filtering on the thermostat wiring or replace the wiring with a Fiber Optic
> link for the RS-485 data on the Thermostat wiring. By the way the
> thermostat wiring is not the typical five or eight conductor wiring, but is
> only four wires. Two for 24VAC and Common coming from the inside Air
> handler, and two for the balanced RS-485 data communicatins from the
> Thermostat. It is a Rheem ECONET communicating type thermostat.
>
> Well that is bit long, but I thin I've covered most of my proposed
> solutions. Of course the respect to solving RFI/EMI issues nothing is cast
> in stone and there may have to be a few more "goodies" added to the
> filtering effort. This effort will take a bit of time as mentioned above
> But I'm retired and have a lot of time to play with this.
>
> Regards to all,
>
> Karin Anne Johnson P.E. K3UU
> Palm Harbor, FL
>
> ________________________________________
> From: Don Kirk [mailto:wd8dsb@gmail.com]
> Sent: Tuesday, October 27, 2020 11:24 AM
> To: Karin Johnson
> Subject: Re: [RFI] Request For Comment (2nd Post)
>
> HI Karin,
>
> If it were me I would spend a little money on a commercial power line
> filter
> like the Delta Electronics 30DPGS5C and see if that puts a dent in the RFI
> (if anything just for a simple test). It only costs $35.31 if purchased
> from Mouser plus shipping. I sometimes have to use a commercial power line
> filter in conjunction with a common mode choke per the K9YC design to
> totally eliminate RFI from equipment that has inverters, etc. but sometimes
> one or the other by itself is adequate. If the combination of them does
> not
> kill the RFI I would then use a 1 or 3 inch single turn loop sense antenna
> connected to a receiver to see where the signal is leaking out of the
> enclosure (like along the thermostat line, etc.).
>
> I understand you have extensive background in power electronics, but
> expecting the manufacturer or installer to change things besides installing
> a commercially available filter internally is asking a lot and very time
> consuming.
>
> I have run into numerous cases where power electronics like variable speed
> drives specifically say they only meet EMI regulations when used with an
> appropriate power line filter and they even list what filter should be
> used,
> but system integrators rarely design in the appropriate power line filter
> (if any), and this leads to the emission of RFI out into our environment.
> I
> ran into this with an apartment complex kitchen ventilation fan variable
> speed drive as well as with variable speed drives in multiple injection
> molding machines located a great distance from my QTH. Simple Delta
> Electronics filter like what's mentioned above except designed for 3 phase
> solved the injection molding machine RFI and the power line filter
> specified
> by the manufacturer of the apartment complex variable speed drive
> eliminated
> that RFI. I understand these cases are not exactly what you are dealing
> with since the power electronics is part of the total design in your
> system,
> but using a dedicated commercially available power line filter is certainly
> a reasonable approach even if just to prove a point to the manufacturer of
> the RFI generating gear.
>
> Just some thoughts from my end.
> 73,
> Don (wd8dsb)
>
> On Tue, Oct 27, 2020 at 9:52 AM Karin Johnson <karinann@tampabay.rr.com>
> wrote:
> Hello Group:
>
> This is second try to post. First one never showed on list(sent on 10/21).
>
> I've posted in the past about RFI from a new RHEEM A/C system. I am
> posting
> two links to Google Drive, which are power point documents. One of them I
> Posted previously, the RFI Spectrum Analyzer photos. The second document I
> Just created with some pictures of the board layouts in the outside A/C
> Compressor unit.
>
> I would very much like to get some feedback from the list about the issues
> I
> have regarding the wiring layout shown in the pictures. I know I can't
> Encompass all of the possible issues shown in the pictures but I have tried
> To list a few.
>
> The main reason for posting is that I don't have any knowledgeable
> individuals, or other ham folks who might understand some of the issues
> Involved in controlling RFI/EMI, that live locally who I can communicate
> with. This list has been helpful in the past And I hope will be helpful in
> the course of solving my problem with this Unit. I am working now with the
> installer company and hope to have better Cooperation with them.
>
>
>
> Here are the two links to Google Drive:
>
>
>
> 1 - CompressorElectronics Link
>
> https://drive.google.com/file/d/18zwBme-avmMDgkQabI9mOjPdprkhQ8aQ/view?usp=s
> haring
>
>
>
> 2 - RFISpectrum Link
>
> https://drive.google.com/file/d/1ku9NwkELhui2IsTUHYg3vfHuPsLvWwpC/view?usp=s
> haring
>
>
>
> Regards,
>
> Karin Anne Johnson P.E. K3UU
>
> Palm Harbor,FL
>
>
>
>
>
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>
--
*Dave - WØLEV*
*Just Let Darwin Work*
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