George,
        If this link blows with 1KV across it, it probably won't blow at
all!!  The voltage will arc across the opening track, carbonize the board
surface and attempt to continue to flow through the carbonization.  High
voltage fuses are different than the usual to prevent that kind of problem.
        Good Luck,
        Howard Feldmesser
        The Johns Hopkins University Applied Physics Laboratory

>   I searched the ipc.org archives but didn't come up with any relevant
>hints on how to design a fusible link into a circuit board.  I want to
>run a 50 mil trace but neck it down to some value for about 200 mils so
>that if overcurrent is applied I'll know where it'll blow.  This would
>be such a rare occasion that a fuse is not warranted nor practical due
>to high voltage, >1000.
>   Does anyone have any idea on how to tackle this?  What calculations
>should I use to determine when the neck down will fry?  The IPC curves
>are very conservative in our experience.  I want it to blow not glow?
>:-)  Remember that the nearby 50 mil trace will heatsink the neck down
>to some extent.
>   Thanks for any input.  Any replies direct to me will be concatenated
>and disseminated over TechNet unless otherwise requested.
>
>George Uptain - Schlumberger Well Services
>512-331-3183
>Austin, Texas
>
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