> Another way to limit the surge is to use Crossing Relays. I use two 40
> crossing relays on a 4000 volt/2 amp HV supply, and it works great.
> work by not completing the circuit until the amp draw would be zero during
> the 60 cycle phasing.
I've seen solid-state zero-crossing switches used for this purpose.
However, maximum current is achieved in just 90-degrees at 60 Hz (assuming
no zero reactance in the circuit). This equates to only 4 ms. It this
sufficiently enough time to limit filament current in-rush, especially with
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