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Conducted emissions conundrum

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NiHaoMike:
In my experience, Meanwell does have a reputation for being electrically noisy. In one place I worked at in the past, they kept a specific model of Meanwell PSU as the reference for a noisy supply.

Psi:

--- Quote from: NiHaoMike on August 10, 2020, 02:30:17 am ---In one place I worked at in the past, they kept a specific model of Meanwell PSU as the reference for a noisy supply.

--- End quote ---

hehe, doesn't surprise me.

TimNJ:

--- Quote from: Mr. Scram on August 10, 2020, 02:19:24 am ---
--- Quote from: jkostb on August 05, 2020, 06:07:35 pm ---I recently finished a product which had to comply with the EU medical device directive. This means it had to comply with IEC60601. The power supply was a Meanwell power supply (as yoiu probably guessed), because this was the cheapest medical power supply with very good specs. During EMC testing we discovered that the conducted emission was exceeded. During the design we had paid special attention to EMC, board layout and filtering.  All power supplies were heavily filtered with common mode chokes, ferrites etc. We suspected that the root cause must be in Meanwell power supply, so we asked Meanwell to share EMC test report. Meanwell was not willing to co-operate. For this reason we replaced the power supply with a TDK-Lambda power supply and retested the product. This time our product passed the EMC test for IEC60601 with a large margin for conducted emission!  I suspect that Meanwell test their product with a resistive load during EMC test. This is of course not realistic if your product contains switching regulators.  Later I opened a meanwell power supply and compared it to a TDK-Lambda power supply. The TDK lambda power supply was 2x times more expensive but the build quality, filtering was a lot better.

--- End quote ---
It surprises me Meanwell isn't sharing the tests reports freely, let alone upon request. If they can't pass EMC testing or prove it they're not much better than any other generic unbranded outfit. I really thought better of them as they're reasonably well regarded.

--- End quote ---

I think you'll notice most of the popular (low-ish cost) companies do not publicly disclose their 3rd party reports. They typically just show the certificates, i.e. the cover page of the report. I agree it does come off as rather suspicious.

jkostb:
The Meanwell power supply which failed conducted emission  in my project was an ACDC adapter GSM60A12. This is a medical power supply. My suspicion with Meanwell power supply started, when I discovered that they were not willing to share their EMC test report. Why on earth does a company not want to share their EMC test report unless they have somehthing to hide? When I contacted TDKLambda and requested for EMC test report I received immediately complete documentation set including EMC test report! From the TDKLambda EMC report I learned that all measurement were performed by an accredited lab. I was really very surprised that our project passed conducted emission test with a large margin without any modification to our electronics, while it failed with the Meanwell power supply. If we did not tried another power supply, we would have spent weeks debugging the electronics, adding filters etc. Be carefull with cheap power supplies!






















Mr. Scram:

--- Quote from: TimNJ on August 10, 2020, 04:40:27 pm ---I think you'll notice most of the popular (low-ish cost) companies do not publicly disclose their 3rd party reports. They typically just show the certificates, i.e. the cover page of the report. I agree it does come off as rather suspicious.

--- End quote ---
It should be outright illegal. If you claim a standard you should be able to prove it. No proof, no claim.

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