Brother, you're describing a line-voltage surge/spike.
Just in case, having worked in industrical electronics most of my life, I'd look into
RFI/EMI (Radio Freq/Electro-Magntic Interference) for your close proximity circuits.
Replacing the 30m cable with a shielded cable may be enough to solve your problem,
if it's a EMI spike problem.
I'm confused, so I think you might be confused about the EXACT source of your problem.
Sure, I know it's the 'fly press'. But it still COULD be feedback noise or a pulse on the
power input line, interferring with your production information line. And/or the over-the-
air EMI pulse created when cycling the fly press.
Your description tells me you're convinced it's an EMI pulse (your EMP pulse).
You could be totally correct, just don't discount the power-line noise completely yet.