Dielectric Capacitance System prevents you from being damaged by shocker zombies as long as you have available bionic power.
Thermal Dissipation prevents you from taking damage from fire - though your gear will still get burnt, so it’s only so-so useful.
Unified Power System is a UPS, and can provide power for any device that needs a UPS for power. It’s useful for power armor, for instance, but you can modify just about anything to run off a UPS.