Hi Attached line drawing of my circuit, Inverter produce single phase high voltage, then this high voltage AC step down to lower voltage than it rectified by diode then output goes to a resistive load. Load is 21V and 105A.

A X2 0.68uf cap 275Vac rated connected across output terminal to reduce noise to pass Conducted emission test. and it helped(20-30Mhz range). but after running for 10-12 hours at this load , the cap get failure ( got open).

any suggestion enter image description here

  • \$\begingroup\$ What is the purpose (and value) of the inductor shown in your schematic? \$\endgroup\$
    – Dave Tweed
    Dec 20, 2015 at 12:55
  • \$\begingroup\$ Value is 17 uH, purpose is smoothing current, Control DV/DT ( High Freq) \$\endgroup\$
    – Electra
    Dec 20, 2015 at 13:09
  • 2
    \$\begingroup\$ Have you calculated the ripple current in the capacitor? Does it exceed its rating? \$\endgroup\$
    – Dave Tweed
    Dec 20, 2015 at 13:19
  • 3
    \$\begingroup\$ I think you'll find X2 caps are rated for mains frequencies, not 10s of kHz. \$\endgroup\$
    – Neil_UK
    Dec 20, 2015 at 13:27
  • \$\begingroup\$ Also that is an AC rated cap, you have a semi DC load, there is never a reverse voltage to stop internal ionization. Also user44635 nailed the frequency thing. High frequency causes insulation to breakdown at much lower voltages. \$\endgroup\$
    – MadHatter
    Dec 22, 2015 at 15:18


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