Steve Holdoway wrote:
This site does have a UPS - a small one, but it couldn't provide protection against this spike. As most can handle about 50,000V, that's a bit scary! We could do with someone (Volker?) to explain the physics of the problem...
I can have a stab at it. 50,000 volts isn't that scary, most MOVs will absorb that at long as the spike duration is short, as will the Class X2 caps. A simple isolation transformer will again absorb much of that spike too. Even the simple inductance of a long line will blunt the spike, BUT, a switchmode supply can self destruct in such a way as to pass that spike right through. The transformer has little core metal and is designed to operate at high frequencies, reacting to the fast rise time of the spike, passing it on.
Cheers, Rex
