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As per ray mack's book "demystifying switching power supplies", on page 59, x2 caps, by definition , can withstand 2.5kv transients......i am not sure if this means for 1 second though, does the datasheet shed any light?
I would not expect it to survive that degree of surge.
By accident I once subjected a 10V electrolytic capacitor to 16V. Instantly it burst, shooting the small metal can up into the air like a bullet. Bits of brown paper flew all over the place.
Your capacitor construction might allow you some leeway. There used to be a label WVDC which stands for working volts DC. It could endure some amount of surge and/or peak V. But how much amount was hard to tell ahead of time.
X capacitors are the capacitors that go across the power line. There are x1, x2 and x3 all with different specs. They are rated to take big line surge hits and are fail safe (will not fail shorted). You can drill a hole through them and they will still function.
yes, X2 caps are indeed rated for the big surge hits, though unfortunately they are not the last word in low ESR. Metal polypropylene caps are better in this respect. This is why the X2 caps are a problem in PFC stages, because there is little capacitance at the front end, and the X caps obviously form a rather large percentage of it, and so a significant ripple current flows in the X caps which isnt really wanted.
Anything that is connected across the power line which, if shorted, could cause a fire or a shock hazard must be a safety-rated device.
For capacitors, the safety agencies have developed the X and Y ratings and have been thoroughly evaluated for the most common type of abuse they commonly see in those applications.
Even if it the capacitor does fail, it will not fail shorted.
But if you really want to be sure, use a higher rated capacitor: a X1/Y2
i see your point Schmitt trigger, i always kind of think that too, but at the end of the day, you have a fuse there, so any short will just blow it, and all will be well again. i think that stipulation specifically concerns capacitors , because some of the old ones were flammable.
I havent seen safety rated bridge rectifiers for example.
Just saying because as we know, there are thousands and thousands of regs and its always interesting to try and clarify them. Partly because nobody can afford to buy them all to read.
I think the rectifiers are not of concern because they do not burn. But i always wondered why the capacitor bank after the bridge did not have to be safe. Any type of capacitor can go there AC or DC.
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