Surge protection box? That's the UPS's job usually. How much juice do you need? I was expecting 1 UPS for the whole observatory; or maybe one...
Could you send some photos of your setup? Are all 3 UPS units on the same electrical ground?
Is everything (all the power supplies) plugged into a common AC source with common ground point? Am wondering if you have a ground loop somewhere...
Separate names with a comma.