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Electronics => Power/Renewable Energy/EV's => Topic started by: Faringdon on July 17, 2021, 04:08:43 pm

Title: Y caps better directly across transformer in offline flyback SMPS?
Post by: Faringdon on July 17, 2021, 04:08:43 pm

Page 4 of the Mornsun LS15-13B12 power module (Offline flyback, 12vout, 15w out) shows a Y cap from primary ground to secondary ground. This is obviously for common mode filtration. But wouldnt it be better if it was actually fitted on the Mornsun PCB and placed right across the actual isolation barrier, immediately next to it?

Mornsun offline power module
https://www.mornsun-power.com/html/pdf/LS15-13B12SS-F.html (https://www.mornsun-power.com/html/pdf/LS15-13B12SS-F.html)

Title: Re: Y caps better directly across transformer in offline flyback SMPS?
Post by: voltsandjolts on July 17, 2021, 04:13:25 pm

Please stop. Please.

Title: Re: Y caps better directly across transformer in offline flyback SMPS?
Post by: jonpaul on July 19, 2021, 01:28:12 pm

No reason, the module supplier is showing various safety and EMI components external to the module.

Diffreent applications will demand different X, Y caps, fuses etc eg Japan/EU/USA or application areas, eg medical/broadcast/consumer/industrial.

Jon

Title: Re: Y caps better directly across transformer in offline flyback SMPS?
Post by: Faringdon on July 19, 2021, 04:12:39 pm

Thanks, though you would agree, that Y caps across the isolation barrier need to be as near the transformer as possible?

Title: Re: Y caps better directly across transformer in offline flyback SMPS?
Post by: Gyro on July 19, 2021, 09:42:34 pm

Y caps are far more accessible in through-hole. You should have noticed that the Mornsun module is completely smt.