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In Reply to: MKP AC capacitor for PSU posted by SandroN on March 6, 2007 at 04:59:51:
...running on them, not just HALF the waveform that's used to calc the RMS value? So a 250VAC MR cap sees, continuously, 250VACRMS times 1.4 to get it to the zero-to-peak half of the P-to-P waveform and then times 2 to get it the entire AC waveform the cap's exposed to. That's c. SEVEN-HUNDRED Volts that must be contained by the layers of film.I've seen many MR caps with both AC and DC ratings that have DC ratings FAR in excess of 1.4 times the DC number; sorry I wasn't keeping notes or I could send you to some.
I have a pair of 805-based SETs using ASC-brand 440VAC MR caps on a 920VDC rail that's SS rectified and surges to some 950VDC - 970VDC on turnon; they've run for a couple years just finely.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
Follow Ups:
IF and only if you KNOW that the AC rating is RMS, yes, then you can use 2.8 as the multiplier. Seems I found out some AC-rated caps are rated with peak AC Voltage.I guess if you want to be conservative, use 1.4.
But I'm not removing those 440VAC MRs from those 805 SETs. :-)
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
I agree with you.
I think AC capacitors are very robust capacitors.
I imagine a capacitor capable of running 250Vac with high currents will see 360Vdc or even 450Vdc as a easy job.
Who else agree with this?
...that the multiplier is 2.82, not 1.41.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
Hi.So how many hours you ACTUALLY switched on your amp in these "couple years" ?
...my 1.4- v. 2.8-multiplier question, or are you just trying to be a smartass?
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
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