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I am using a capacitor which is rated for 630V DC. I want to know the AC voltage rating for this capacitor.

This is the capacitor.

This is its datasheet.

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    \$\begingroup\$ What does the datasheet say? If there is no AC rating then there is no rating, meaning that you're on your own if you use this capacitor with AC. From the AC voltage (peak, RMS etc.) it can be calculated what the maximum voltage is and that should be lower than the DC rating. However, a capacitor without an AC rating isn't guaranteed to work safely with AC. So a smart engineer would simply select a different capacitor (with an AC rating). \$\endgroup\$ Feb 10 at 9:47
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    \$\begingroup\$ <after looking at datasheet> Indeed these capacitors have no AC rating. They appear to be designed for electric cars with high DC voltages. I would NOT use this type of capacitor with (mains) AC, they're not designed for that. If you ignore this advice and the capacitors blow up and/or start smoking and/or catch fire then don't complain to me or to TDK. Choose a different model capacitor. \$\endgroup\$ Feb 10 at 9:51
  • \$\begingroup\$ How are you going to use this capacitor? Do you intend to use this capacitor with AC mains voltage? \$\endgroup\$
    – Justme
    Feb 10 at 9:57
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    \$\begingroup\$ The word "current" or "amp" doesn't appear in that datasheet. Find capacitors that do mention the current rating across a range of frequencies. Then you can be assured. \$\endgroup\$
    – Andy aka
    Feb 10 at 10:38
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    \$\begingroup\$ Manjesh - Please put all available information in the question eg "I will be using this in the resonant converter which is secondary side " is vital information which would have been much better in the original question and should be added. Plus anything else known and even possibly relevant. \$\endgroup\$
    – Russell McMahon
    Feb 10 at 19:26
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The AC voltage rating is the maximum Voltage the capacitor can handle divided by the square root of 2.

So this capacitor can handle 630V / 1,414 = 445,5V

I wouldn't go higher than 400VAC though.

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    \$\begingroup\$ Nick - that's for a sine wave. He notes in a comment "I will be using this in the resonant converter which is secondary side ". That may well be sinusoidal, but needs confirmation. \$\endgroup\$
    – Russell McMahon
    Feb 10 at 19:24

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