I have posted a LTspice (Spice) simulation file that I have used to investigate
the operation and energy dissipation in: a B+ glitch resistor, B+ series
HV-fuse, main contactor shut off, B+ crowbar shunt. You can also vary
rectifier smoothing capacitance (eg from 20 to 40 uF) as well as the combined
HV transformers and rectifier banks series resistance. I have used voltage
controlled switches driven by carefully timed pulse generators to achieve a
typical HV PSU timing in LTspice.
According to Eimac a max dissipation of 4 Joules is allowed on the grid of an
YC-179 and similar tubes.
It seems like that with only a glitch resistor and a HV fuse, it may be
difficult to get below 10 Joules of energy dissipation with an A to G arc. I
have taken the time integral of the product of current and voltage over a
typical glitch timespan and a 190 ohm glitch resistor in a 6KV DC supply will
probably not get you below Eimac's maximum recommended dissipation. Also
according to the data-sheets of Elschukom (a German quality manufacturer of HV
fuses) a 10 KV HV fuse that has 10x rated current flowing thru it will not open
before 10ms has elapsed. In that time it may be too late to prevent damage, if
I am correct. You may be surprised by the results of the simulation. I was.
However I may be wrong, so your comments and observations are welcome.
You are also welcome to download the simulation yourself to try it out. You can
see the schematic, investigate the simulation curveforms and download the
simulation files to try them yourself here: http://www.lb3hc.net/?p=1171
73
LB3HC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|