3 ms·
"Cant creep across empty space " No, but it can arc, which now explains perfectly why my motherboard failed, and threw an arc across the battery and sent out a
by ForOldHack 2y ago
"Cant creep across empty space
" No, but it can arc, which now explains perfectly why my motherboard failed, and threw an arc across the battery and sent out a jet of flame. I kept it around to show people what could never happen - does. Now long lost.
- amelius 2y agoWait, how small are the distances inside a supercapacitor?
- dmoy 2y agoSmall Air is like 50V per mil. Cheap plastic is like double that? If the voltage of a given supercapacitor isn't high, then air could work fine I suppose. At least on those two dimensions, I haven't considered anything else. Air will have less creep than most (all?) materials, but worse voltage limits.
- paulgerhardt 2y agoGlass immediately comes to mind as having less creep. If you go back to the Faraday, Hertz, Tesla et al days when they were arcing kilovolts across their labs you’ll often see them using glass insulators. Some ceramics and Teflon too.
- dmoy 2y agoMy recollection is that glass has drastically higher dialetric constant than air, but more creep (still very little creep, but more than the ~0 of air). If you're arcing kilvolts, you want that higher dialectric constant, and probably don't care about small amounts of creep. If you're building a supercapacitor, that equation might be different because the voltages can be quite small. I've been out of EE for a long time though, so maybe I'm misremembering things here.
- pjc50 2y agoThis is indeed one limiting factor of supercapacitor design: the dielectric needs to be as thin as possible to increase capacitance, but not so thin that the working voltage of the capacitor exceeds the breakdown voltage of the dielectric's insulating ability.