> It's still not an INSTANTENOUS function. A cap doesn't discharge all of
> it's energy at once. And 20 amps from 1 uF sounds like an awful lot.
It depends entirely upon the ESR and impedance of the discharge
path and the components.
Most large (220 mFd 450 volt for example) electrolytics have about
1 ohm ESR and several uH of inductance. At 450 volts, they can
supply quite a bit of peak current to a direct short.
Of course you have to know the impedance of the entire discharge
path.
> So at 4000 Volts and 640 Amps, we get 2,560,000 Watts.
>
> Is the typical ham amplifier power supply really capable of delivering a
> peak power of 2.56 MegaWatts?
It's quite possible one with a large oil filled capacitor is, but not for
very long and only with a crowbar across the capacitor terminals.
Add the ESR of 10 electrolytics (~10 ohms) and the ESR of wiring
and the plate choke (~5 ohms) and current is limited to something
less than 266 amperes (there is inductance also).
200 amperes can collapse a plate choke, make a loud bang, and
might even damage a grid or filament if conditions are just right.
The problem is to obtain that much current, the tube or some other
component on the HV side of the blocking cap (or the blocking cap
itself) must be arcing. The tube itself, without an arc could never
pass that much current.
73, Tom W8JI
w8ji@contesting.com
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