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I have these two ceramic capacitors shown in the image below:

enter image description here

It seems to me that both of them have 2.2nF capacitance and the first one has 400V rated voltage while the other one has 1000V rated voltage.

I wonder if there is any difference between them (except for rated voltage) and in case they are the same why is the first one twice as big (although it has smaller rated voltage)?

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  • \$\begingroup\$ How about supplying links to the data sheets for each capacitor. \$\endgroup\$
    – Andy aka
    Jun 10 '16 at 9:40
  • \$\begingroup\$ @Andyaka I salvaged them from old electronic devices I don't have their datasheets. \$\endgroup\$
    – razzak
    Jun 10 '16 at 9:43
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The capacitor with the 250V AC rating is an X and Y rated capacitor and is capable of being applied across the incoming AC in your house. It's bigger because its reliability is much better i.e. it won't form a short circuit if it fails. Here's the idea behind them: -

enter image description here

As you can see a Y rated capacitor is designed to be between line and earth thus a properly designed capacitor will not short line to earth (electrocution possibility). The X rated capacitor can be put across live and neutral and does not need a fuse i.e. it does not pose a fire hazard because it fails safe = open circuit.

The capacitor on the left is therefore bigger because it is more reliable in these scenarios.

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  • \$\begingroup\$ Sorry I'm still new to electronics, can you please explain to me what does X and Y ratings mean? \$\endgroup\$
    – razzak
    Jun 10 '16 at 9:46
  • \$\begingroup\$ Try this: google.com/… \$\endgroup\$
    – Andy aka
    Jun 10 '16 at 9:51

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