On 20/09/2011 11:13, peter green wrote:
> Remember the real equation for a capacitor is Q=3DCV differentiating this
> with respect to time and knowing that current it is the rate of change
> of charge gives us I=3DC(dV/dt) (for those who stopped studying maths
> before taking calculus this means that the current though a capacitor is
> proportional to the rate of change of voltage across the capacitor)

i.e. for a really sharp spike the capacitor looks like a short circuit=20
no matter what the voltage is.

Also capacitors are more prone to short circuit isolation failure than a=20
transformer or optocoupler.  Inherently an unhappy solution for mains=20
isolation.
--=20
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