SVDC for a capacitor?

[Wakarusa]

Trying to source some capacitors and noticed
1) Illinois no longer lists anything with a 500 WVDC rating in their standard aluminum electrolytic product listing ('cept big motor start/run snap-ins).
2) The aluminum electrolytics have a "SVDC" rating that seems to always be WVDC+50V (so a 450 WVDC cap will have a 500 SVDC rating).

So, old school guy that I am, I get that WVDC means "Working Volts Direct Current" and I even fully understand what the term means re: what the capacitor will tolerate.

What in hell is SVDC? New marketing term to indicate they've been selling us 450WVDC caps marked for 500 all along?

[VacuumVoodoo]

This is Surge Voltage, usually specified together with maximum time this voltage can be applied.
When forming caps at factory a forming voltage 10 to 20% higher than rated operating voltage is used. This leaves you some margin as to how much you may want to exceed rated voltage in continuous operation - which you really should not. Apart from apparent risk of caps blowing up lifetime is severely reduced. The caps must be rated so they can operate continuously with mains voltage 10% over nominal without exceeding their rated working voltage.

500V and higher voltage axial electrolytics are not so common. Radial cans are a bit easier. Try Rifa/Evox and Panasonic TSUP snap-in caps in 500V rating.

[Trout]

F & T still sells 500V axial leads in 22uf,30uf,47uf values. I have been using these in a few service jobs over a year with good results. They also sell a dual section can cap that works well in marshalls as well as a few other amps.
32/32 µF @ 500 VDC
50/50 µF @ 500 VDC
100/100 µF @ 500 VDC
Then of course in can caps there is always JJ, They also sell the above values as well as a 40/20/20/20 µF @ 500 4 section.

I am surprised Illinois has dropped the 500V units, I see a few vendors still have them in stock.

Another source of 500V and even 600V axials is Just Radios (http://www.justradios.com/capsize.html)out of Canada.
I have used caps from them and not had any failure issues, plus he is very reasonable on bopth price and shipping and very fast to respond.

Trout

[Wakarusa]

Surge voltage makes sense -- though I don't recall seeing a time spec.

CE Distribution is still selling TTA line Illinois 500WVDC caps. One of the things that led me to this morning's search, however, is that the current TTA 47uF/500WVDC being sold be CE Dist are 3/8" longer than the TTA series found in the '93 PV sitting on the bench :(

Which (shifting the thread a bit I suppose) is one of the other "gotchas" in PCB designs -- the drill mask and layout is often specific to whatever components were being used at the time. So in, ferinstance, an old eyelet board Fender different cap can sizes don't make much difference. In this PV however, 3/8" longer is making it darned difficult to get them mounted and still have the leads clear other components. Bleh.

[Trout]

Surge voltage makes sense -- though I don't recall seeing a time spec.

CE Distribution is still selling TTA line Illinois 500WVDC caps. One of the things that led me to this morning's search, however, is that the current TTA 47uF/500WVDC being sold be CE Dist are 3/8" longer than the TTA series found in the '93 PV sitting on the bench :(

Which (shifting the thread a bit I suppose) is one of the other "gotchas" in PCB designs -- the drill mask and layout is often specific to whatever components were being used at the time. So in, ferinstance, an old eyelet board Fender different cap can sizes don't make much difference. In this PV however, 3/8" longer is making it darned difficult to get them mounted and still have the leads clear other components. Bleh.

I know exactly what you mean, I ran into that myself.
I would point out that the caps Just Radios sells in most cases are not as long or large in diameter compared to FT, JJ, and IC.
Pretty much the size of the Ecaps in some of the kit amps.

I think as more time passes, this problem is only going to get worse, and you can only store these things so long so buying big loads is not the best answer either.

Trout