RPC Capacitor questions

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Hey Larry,

Close, but no cigar!! Try the one I included in my first post to the thread.

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The place is amazing. Anything from aluminum to zirconium, and the only place I've ever seen nose sections of some kind of missile. I understand (hearsay) that a lot of props for the movies are picked up here. You could make a few thousand of the "Danger! Danger Will Robinson!!" bots, or a pretty good semblance of the plane in Flight of the Phoenix. And electronics gear and test gear is their forte. Wire??? Never seen such piles an heaps of wire!! Stacks of IBM 360 computers. I was serious about it being a "jungle" though, complete with a feeling of canopy overhead (the stuff is piled at least 12 feet high)!! Something special you want, then just ask at the counter, if you can find it! It's near the entrance someplace. Shout if you get lost, and they'll send out a team or a homing signal.

Take care.

Brian Lawson, Bothwell, Ontario.

Reply to
Brian Lawson
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On Wed, 19 Oct 2005 20:34:56 -0400, with neither quill nor qualm, Brian Lawson quickly quoth:

Ah, that's a little bit easier. I had missed seeing the original few posts in that thread.

It must be big if you can see it all the way from the odd side of Canuckistan! ;)

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Reply to
Larry Jaques

The minimum is 1.56 times the nominal line voltage.

This comes from ( ( 2 ) ^ 1/2 ) * 1.1 = 1.56 (to two decimal places).

( 2 ) ^ 1/2 converts RMS voltage to peak voltage (and assumes no harmonics are present).

1.1 applies a 10% safety factor.

For a 240 line, the "precise" minimum us 373.35, but 370 is perfectly acceptable.

Reply to
Peter Haas

As I understand it, a capacitor rated for 370 VAC is rated for 370 VAC. Now if the Capacitor is rated at 370 VDC, it may or may not be good for 240 VAC. It depends on the foil thickness. A metalized foil cap used for AC will heat up and fail prematurely.

I have some capacitors that are rated 600 volts DC or 330 volts AC 60 cycles. Note the AC rating is not the DC rating divided by 1.56. Also note the rating is based on the frequency. The reason is that when DC is applied to the capacitor, there is pretty much no heating caused by the current in the capacitor.

Also note that the voltage rating for capacitors is based on a failure rate at that voltage. I forget the numbers, but a home shop user is not likely to ever come close to the number of hours that a capacitor is expected to last. Consider that these are capacitors that are rated for continuous use 24/7 for maybe 20 years.

Dan

Reply to
dcaster

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