| Electronics > Projects, Designs, and Technical Stuff |
| AC/DC 500W Supply EMC Issue's |
| (1/1) |
| fordj06:
Hi guys I'm a EE student on placement and I've just taken over an existing power supply design that was never EMC tested. We are now wanting to put the design into a system that needs to be certified for EMC class A (EN 55032 CISPR 32). I took the system to the EMC test house the other day for some pre-compliance testing and it failed, miserably. We determined that it was the AC/DC power supply that was the source because the system was still failing with just the power supply in the test rack. We are using a PFE500SA-48 from TDK-Lambda as the main power module and have used the same supporting passives as they used for there in house verification. (See attached schematic). Some notes from the pre-compliance: - It failed both emission and immunity - When we increased the size of the earthed chassis the results were worse - It was failing at around 30MHz (Ive attached some results) - It was broadband interference Any experience would be appreciated. Thanks |
| moffy:
Have you tried a suitable ferrite in series with the mains cable to attenuate the 30MHz etc? |
| poorchava:
Am I missing something or you don't ahve a capacitor between primary and secondary ground? Ie a way for interferences to close the loop. you could try adding a small (eg 4.7n y1 type) capacitor between grounds. |
| T3sl4co1l:
Probably do this. L1 probably isn't doing much. What's conducted look like? Tim |
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