[Amps] Glitch resistor + fuse?

[Steve Thompson]

A triggering circuit such as shown on p4 of:
www.qsl.net/g3uvr/4cx250/G4AJW-psu.pdf
could do the job. Multiple secondary windings could feed stacked 
thyristors so no added PSU needed, and an extra one to feed 
something to shut off the mains breaker.

Farnell have 1.6kV 70A thyristors at $8.

Steve

> I wonder if any US readers use a crowbar circuit as described in the Eimac
> paper to really cut down on the energy a valve has to endure during an arc?
> There is the outline of a circuit using a string of thyristors (SCRs) in
> figure 2 here
> 
> http://www.qsl.net/oe5jfl/flashover.htm
> 
> although the circuit does not offer protection during the first half
> second, until the gate trigger reservoir capacitor has charged up. It also
> may not keep the thyristors triggered for 20ms or more, until after the
> primary-side relay/breaker/contactor has dropped out. A better approach
> might be to use transformer coupled gate triggering, driven from the low
> voltage DC supply that is already provided for the control logic. Some kind
> of pulse train circuit (NE555?) would be needed to keep the thyristors
> triggered during the "follow on" phase.
> 
> 73, Alan G3XAQ