Interferance/supression capacitors across 230Vac Line on SMPS

Jul 13, 2006 3 Replies

Any input please. The switchmode i have at the moment completely fails it's mains leakage test (using a PAT4 tester) because of residual current leakage to earth (through the 0.047uF/275V Wimas) of 4.3mA. These capacitors have been in use on the aged SWPS for up to 12yrs constantly so is it possible they will have broken down minimally (although the 4.3mA is probably acceptable as a leak for this kind of application). On the other hand, is there a more prefered type supresssion device today, perhaps ex RS Components?. Thanks... pete



Yes it will do.

That's why 2200 or 2700pF is a very popular value for Y caps !

Graham

In case I wasn't clear - those caps are simply too big.

If you reduce their value the RFI will be worse but maybe you can live with it ? If there's room fit a self-contained filter.

Graham

?

Thanx Graham

Will try some 2200pF and see what their mains leak is and then check any RFi issues..

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