RFI From Inverter

[Pwablo]

Hi ,i know this may not have any bearing on the above ,but we fitted loads inverters forAHU fan motors, pumps etc .Replacing star/delta starters . Mostly in hospitals ,so didn't want spurious RF in a hospital environment.
Where possible we kept the inverter as close to the motors as possible, as 3 phase mains supply was alway unscreened, but from the inverter to motor, was wired in screen cable ,and the screen cable was specifically required to be SY cable and glands to prevent radio interference .
These were Danfoss Vlt FC 301Inverters, ABB ACS550 and LS 100 series . Google the installation instructions and they explain in detail how cable screen is to be terminated .
Cheers Steven

​

Thanks Stevie for the information. I was thinking about cables and screening today, although the runs from the inverter to the EMC filters would be very short. I was considering the implications of having unscreened cables and if this would produce detectable amounts of RFI. I also noticed that Schaffner make filters specifically with PE linked Capacitors for installation in medical environments, and wondered what benefits these brought over the ones without PE linked capacitors?
I will do a bit of research into the cables you mentioned. Thanks again.

 

[Radiotowers]

Hi there...Thanks for making a post. I dont have access to that article in ARRL unfortunately, but I will have a look for it and see if I can find it outwith ARRL. I was looking for David Lauders article in Oct 2023 Radcom also, but RSGB have website issues and Im having difficulty getting that also. I generally dont have any local RFI issues to worry about as Im very rural....I have had zero noise floor and very little unmanageable RFI for 13 years. Thats what makes this situation so gutting.... from zero to 80% of HF wiped out over night. My spectrum scope on the IC7600 now has 4khz wide blank carrier spikes that are S9+15dB, every 30khz from 8Mhz to somewhere over 30 Mhz (although I suspect it goes a bit higher, I just dont have resonant antennas between 30Mhz and 2m band to see how far up it goes)

Growatt where pulled up in Sweden for non compliance regarding EMC. I dont know what model it was but it was published online....PV Magazine
The Dutch seem to be a bit more proactive in addressing Solar PV EMC Issues also, stating that MOST Inverters do not meet the EMC standards... HERE

If you are getting RFI on your own system then tracking down the leak path and sticking in a few dedicated EMC filters shouldnt be too difficult. You dont have to live with your solar RFI.

EDIT - Found a pdf online. Interesting read, however his sytem was using optimizers. In my case the system has none, and is simply a very dirty inverter.

 

[Radiotowers]

Ok Paul,
I have built a mains filter feeding the rig/ computer etc using the details from GM3SEK , this seems to have the same stuff as the article mentions.
So incorporating a mains filter inline with the fed to the consumers unit should be an easy hit, something you could build , install into a plastic box and leave the solar installers to connect up. The same with the ferrite cores, a simple extension wrapped round the cores and then connected in series with the existing strings.
There are of course the BIG clip on ferrite cores ( think the last time I bought mine they were about £14 each) .
Of course the big problem is that you dont know if any of this will help .
I will probably incorporate this myself sometime this year .
Thanks for the links about Growatt I will check that out .
Bill

 

[Pwablo]

In my last house I had severe interference knocking out my internet (ADSL), I searched for and found the culprit (a nearby commercial garage using Chinese electronic ballasts on workshop lighting). However the owner refused to do anything, BT/Openreach would do nothing, the ISP would do nothing and even though I was able to show blotting out of various AM radio stations neither Ofcom or the BBC wanted to know. So in answer to another comment nobody now enforces the legislation.
I have also encountered various other Chinese products over the years that caused problems, one a laptop power supply I opened up and found all the filtering components had been removed!

The problem with clip-on ferrites is they don't produce enough inductance to effect the relatively low fundamentals and the powerful harmonics of typical switching frequencies of only 10's of Khz, you need pretty big wound common mode chokes. You could try chatting to Wurth UK, they might be interested in providing some samples if they can use your case.

Hi Fella, thanks for your comments. I completely agree with everything you have said. The situation with non compliant devices flooding the Western World from China is out of hand now. On You tube there are videos of people opening laptop PSUs and finding blocks of cement or epoxy resin to give them weight, in an attempt to replace the weight of a Torroid core. All the EMC suppression is absent.
We used the clip on ferrites to see if the RFI was attenuated or not, in order to establish the degree of common mode being conducted in the DC cables and confirm the leak path with the inverter in production mode. These were never going to be a permanent fix and were removed. I did consider getting some hefty coax suitable oval Type 31 mix cores and seeing if this had any affect but as I will likely get one shot at getting the Installers to visit this property to install a solution, I have to ensure its the right one, so opted for dedicated EMC filter route. I will look into Wurth UK, thanks for the info, one more supplier I can try and approach for advice.....Waiting to see what Schaffner come back with first as I spoke too and emailed them today.

 

[Pwablo]

Ok Paul,
I have built a mains filter feeding the rig/ computer etc using the details from GM3SEK , this seems to have the same stuff as the article mentions.
So incorporating a mains filter inline with the fed to the consumers unit should be an easy hit, something you could build , install into a plastic box and leave the solar installers to connect up. The same with the ferrite cores, a simple extension wrapped round the cores and then connected in series with the existing strings.
There are of course the BIG clip on ferrite cores ( think the last time I bought mine they were about £14 each) .
Of course the big problem is that you dont know if any of this will help .
I will probably incorporate this myself sometime this year .
Thanks for the links about Growatt I will check that out .
Bill

Hi Bill
I wish I could just build a homebrew filter for this, would work out much cheaper, but as its a new build and was commissioned by the owner to a property developer who then sub contracted the Solar and electrical works, the install has to comply with RoSH, MSC and all the other standards associated with cosha electrical works. Sadly I have to ensure that whatever is proposed and supplied conforms and is fit for purpose.

EDIT - Had a look at the GM3SEK filter box using the Schaffner EMC Filter and some Type 31 mix cores. Interesting solution to mains borne RFI. I may make one at some point for my shack if I get this received RFI issue sorted. Thanks for mentioning it.

 

[SPECIAL LOCATION]

Welcome to the forum Pwablo....
I can offer no constructive technical input to your question.... But Thanks for posting.

This is an interesting topic, that I don't think we have ever discussed previously..? (I've been here since 2008)
So please do keep us updated with any further information you come across...

Although not directly related:
We are clearly now in an era where large businesses / organisations can 5hit all over "little people" who know exactly how to go about their daily duties and identify that big-business / organisation systems are failing... Even though the big business / organisations deny any failures in their systems!!!

Although you may not be at risk of losing your income/job/savings/home/local reputation etc.....
I do fear you may be fighting a "David & Goliath" struggle, similar to numerous sub-postmasters trying to convince the Post-Office & Fujitsu that their system is faulty and not operating as it should!!!

Wireless interference is a difficult beast to capture and/or remove... From my earlier employment days within the private Telecommunications industry, I do recall instances where head-office tech support guys with some "expensive" kit were needed to track down radio-transmission related problems...

As Appentice87 said, years ago the GPO had a lot of authority over wireless related problems..
But currently we seem to have a whole bunch of toothless regulators who basically can do nothing!!!

And unless there is some monetary gain and/or profits for shareholders... No-One is bothered to do anything???

 

[Pwablo]

Welcome to the forum Pwablo....
I can offer no constructive technical input to your question.... But Thanks for posting.

This is an interesting topic, that I don't think we have ever discussed previously..? (I've been here since 2008)
So please do keep us updated with any further information you come across...

Although not directly related:
We are clearly now in an era where large businesses / organisations can 5hit all over "little people" who know exactly how to go about their daily duties and identify that big-business / organisation systems are failing... Even though the big business / organisations deny any failures in their systems!!!

Although you may not be at risk of losing your income/job/savings/home/local reputation etc.....
I do fear you may be fighting a "David & Goliath" struggle, similar to numerous sub-postmasters trying to convince the Post-Office & Fujitsu that their system is faulty and not operating as it should!!!

Wireless interference is a difficult beast to capture and/or remove... From my earlier employment days within the private Telecommunications industry, I do recall instances where head-office tech support guys with some "expensive" kit were needed to track down radio-transmission related problems...

As Appentice87 said, years ago the GPO had a lot of authority over wireless related problems..
But currently we seem to have a whole bunch of toothless regulators who basically can do nothing!!!

And unless there is some monetary gain and/or profits for shareholders... No-One is bothered to do anything???

Hi. Your comments are so true. I often feel that everything is a David and Goliath challenge these days? In these past four years I have been confronted with so many issues you would'nt believe. Boundary disputes, seeking court interdicts, property rights disrespected, solicitors ignored, structural damage by a rock crusher vibrating, Insurance companies fobbing me off, private water supply pipe damaged with fence posts, the list goes on. This problem with RFI is just the latest challenge. Been here 30 years and came to the country side for a quiet life....Didnt work out too well. Went from a solo house to 4 + a static caravan since 2004.
On the bigger picture, everything seems to be broken these days, especially in the UK. Id struggle to name one sector of governance or social service that works anymore...I often wonder how we got here.....however I digress....
I will definately keep this thread up to date with how this develops. I am currently waiting for a reponse from Schaffner, and the Installer is still on side, so hopefully i can get a mitigation proposal over to the installer and have them ok it, and I will then be able to place an order for the parts and source cables, enclosures etc, and arrange a date to get the kit installed. Of course I dont know if this mitigation is going to cure all the RFI but im hopefull that it will at least tame it to a degree that I can use my radios again and get back close to where I was before all this happened.

ATB

 

[Geoff1946]

How does time of day affect the problem?
I was under the impression, possibly incorrectly, that most HAM radio activity is at night, when presumably the solar panels are inactive. Does your neighbour also have a battery system attached to the invertor?

Another thought, have you any indication of conducted interference coming on your mains supply ?
Your neighbour's system is presumably exporting its version of sinusoidal AC, possibly even on the same phase as your supply, (ironically even providing your power !).

 

[binky]

Hi. Your comments are so true. I often feel that everything is a David and Goliath challenge these days? In these past four years I have been confronted with so many issues you would'nt believe. Boundary disputes, seeking court interdicts, property rights disrespected, solicitors ignored, structural damage by a rock crusher vibrating, Insurance companies fobbing me off, private water supply pipe damaged with fence posts, the list goes on. This problem with RFI is just the latest challenge. Been here 30 years and came to the country side for a quiet life....Didnt work out too well. Went from a solo house to 4 + a static caravan since 2004.
On the bigger picture, everything seems to be broken these days, especially in the UK. Id struggle to name one sector of governance or social service that works anymore...I often wonder how we got here.....however I digress....


ATB

How did we get here? 40 years of neo- liberalism, and that wonderful austerity budget. Funny how we have more millionaires and billionaires than ever though.

 

[Pwablo]

How does time of day affect the problem?
I was under the impression, possibly incorrectly, that most HAM radio activity is at night, when presumably the solar panels are inactive. Does your neighbour also have a battery system attached to the invertor?

Another thought, have you any indication of conducted interference coming on your mains supply ?
Your neighbour's system is presumably exporting its version of sinusoidal AC, possibly even on the same phase as your supply, (ironically even providing your power !).

Hi Geoff

RFI Is constant 24/7. Yes has a Sunsynk 5Kw battery. Even when there was a power cut there was RFI so the inverter is clearly very poorly suppressed or perhaps has no suppression at all ! The RFI is being generated by the high speed switching process in the inverter and being conducted up the panel DC and out the AC cables and radiated (broadcast) a good 300-400m radius from the property. This has all recently been confirmed via the testing that was conducted on Tuesday. The leak path(s) are not in question any longer. I have a 24kv transformer out side my house down the road a bit, and my property is on a different phase from the new build (i know this for sure, cause Ive had my land dug up 3 times to facilitate electrical supplies to the other properties. No mains RFI in my property what so ever, all the RFI is being received by my antennas. I have tested this out with my radio on a 12v battery with the mains switched off. One of the first thing that I had to do before I arranged Ofcom to visit. (I guess they got fed up of turning up and finding Mr X's phone charger next to his TV was the cause of their problems). Thanks for bringing it up though, its a very valid point.

 

[apprentice87]

The u8ltimate answet [if you have the evidence that it is them] is a court injunction as you are entitle to peacful enjoyemt of your property. I would have thought a solicitors letter woul;d do the trick

Is there some sort of independant expert that could confirm what you are saying??

Is thre anthing you could do to trip out all their stuff. a BIG motor stating at regualr intervals??

john..

 

[Pwablo]

The u8ltimate answet [if you have the evidence that it is them] is a court injunction as you are entitle to peacful enjoyemt of your property. I would have thought a solicitors letter woul;d do the trick

Is there some sort of independant expert that could confirm what you are saying??

Is thre anthing you could do to trip out all their stuff. a BIG motor stating at regualr intervals??

john..

Hi John. I looked into this and its a dead end unfortunately, and I am not at that stage yet (Hopefully wont be either!) The only possibility of a legal route is to hire a specialist solicitor and purse Nuisance Legislation. There would be no guarantee of a successful outcome, as impact would be considered much like an impact to your view from your property, and as we all know....your not entitled to a view. It would also be very costly to do. Would be cheaper to hand the installer £5k and tell him to upgrade their system to one from a European manufacturer. The other question is who would I take to court? The Manufacturer? The Developer? The Solar Installer? The property Owner?
I dare say I could do all sorts to try and interfere with my new neighbors, however they are not to blame for this situation, and I am not that type of person, as often as I sometimes think I want to be.

 

[apprentice87]

Hi John. I looked into this and its a dead end unfortunately, and I am not at that stage yet (Hopefully wont be either!) The only possibility of a legal route is to hire a specialist solicitor and purse Nuisance Legislation. There would be no guarantee of a successful outcome, as impact would be considered much like an impact to your view from your property, and as we all know....your not entitled to a view. It would also be very costly to do. Would be cheaper to hand the installer £5k and tell him to upgrade their system to one from a European manufacturer. The other question is who would I take to court? The Manufacturer? The Developer? The Solar Installer? The property Owner?
I dare say I could do all sorts to try and interfere with my new neighbors, however they are not to blame for this situation, and I am not that type of person, as often as I sometimes think I want to be.

Well, they ARE to blame as it is them emitting the interference. Be the same as if i decided to heat my house by burning car tyres and then claimed it was not me making the smoke. They are causing a public nuisance. Public nuisance is now a CRIMINAL offence...

Read this adn hope it helps.. https://insights.doughtystreet.co.u...nuisance-offence-to-prosecute-political-and-e

 

[Pwablo]

A quick update on progress, and some interesting reading (see attachments) regarding this issue from RSGB Oct 2023 EMC Matters by Dr David Lauder if anyone is interested.
I am still waiting for a response from Schaffner's application Engineer regarding the correct filters to use, however this article indicates that on an install with an SMA SB3000HF Inverter which was also producing conducted RFI via the DC string cables (Albeit much less than I am currently experiencing) they use Schaffner FM2410H-8-44 EMC filters mounted in an enclosure. This apparently attenuated the RFI by approx 30dB which removed the S5 of RFI the owner was experiencing (Im getting S9+15dB of RFI !!, so would be looking at round maybe 50 or 60dB of attenuation being required??)
I was also in contact with Sunsynk today, who have escalated the issue up to their 3rd Line Tech Support....Not sure how helpful they will ultimately turn out to be but I need to let them have a say in what they would recommend if anything.

Apologies for the poor quality...but I got these sent to me and they could only take a photo as they had no scanner.

Cheers

 

[Geoff1946]

That makes interesting reading. Perhaps the most telling paragraph is the one highlighting that the standards do not require testing of radiation from the DC inputs. That seems a glaring omission when the standards have been around for twenty-odd years.
Thanks for sharing this topic and I hope your problems are alleviated in due course. It appears that Shaffner is a good choice when they have previous experience.

 

[Radiotowers]

A quick update on progress, and some interesting reading (see attachments) regarding this issue from RSGB Oct 2023 EMC Matters by Dr David Lauder if anyone is interested.
I am still waiting for a response from Schaffner's application Engineer regarding the correct filters to use, however this article indicates that on an install with an SMA SB3000HF Inverter which was also producing conducted RFI via the DC string cables (Albeit much less than I am currently experiencing) they use Schaffner FM2410H-8-44 EMV filters mounted in an enclosure. This apparently attenuated the RFI by approx 30dB which removed the S5 of RFI the owner was experiencing (Im getting S9+15dB of RFI !!, so would be looking at round maybe 50 or 60dB of attenuation being required??)
I was also in contact with Sunsynk today, who have escalated the issue up to their 3rd Line Tech Support....Not sure how helpful they will ultimately turn out to be but I need to let them have a say in what they would recommend if anything.

Apologies for the poor quality...but I got these sent to me and they could only take a photo as they had no scanner.

Cheers

First page I opened when I took the wrapper off( last months mag appeared with both sides of the envelope open !)
regards

 

[Pwablo]

The Feb 2024 issue has also been sent to me, which further discusses this increasing EMC issue with Solar systems. Apologies again for the image quality, however most of it is readable. I have also attached a photo of my radios spectrum scope showing the RFI I am receiving.....my scope looks like this from around 7Mhz to somewhere just over 30 Mhz. Seems to be strongest in the 10-11Mhz range...... 2 off 1/4 lambda elements for the 30m band? about 7.5m long for the DC cables to panels?

Regards

 

[Pwablo]

Some very interesting reading here. This is a translated PDF from the Dutch Regulator RDI from May 2023 which was referenced in the article HERE concerning compliance of Solar Installations to EU standards.

Enjoy

 

[Radiotowers]

Nice link,
It only confirms what we already know, but at least one EU regulator is paying attention but doing nothing as usual. As long as the carbon reduction and energy / economy crisis continues I cant see any sure fire changes.
As usual its left to the consumer to resolve.
thanks

 

[Pwablo]

So a quick update. Schaffner responded with ...."not enough info to make a conclusive determination on products to use" "pick some filters and try them" (my words) kind of reply. Really quite disappointing but it is what it is.
I was contacted by another radio guy who has the same RFI problem, with the exact same inverter model installed in a neighbors property, so I have been trying to help him and have shared a lot of info. He also went to Ofcom and got the same response as I from them.
I also spent a bit of time the other night looking through the installation manual and noted that on page 16 (see attached manual and photo). there is instructions to install "Magnetic Rings" (Listed on page 12 parts list) on both the Battery DC Cables, and the Battery Monitoring Cable prior to terminating them. I asked the guy if he could get some photos of his install and send them too me, only to find that NO MAGNETIC RINGS have been fitted during his neighbors installation. I have emailed the installer in my case asking if these have been installed. I shall leave it up to readers to determine if they think they will have been or not! I do not know what impact on the RFI would be with the potential omission of these Magnetic Rings in my case, however the manufacturer clearly felt that they were needed, and that is why they have been included in the kit.