In order to explain this, I need to explain Kessler Syndrome. As an Exo, I feel a duty to the machine to convey its original purpose. But first: ACD stands for Active Contact Defense. It is not an AC-DC Feedback Fence and it is not named for any work of pre-classical music. I am not winking. That is a malfunction.

Kessler Syndrome occurs when a planet's orbitals fill up with fast-moving debris, which strikes other debris and shatters it in a chain reaction. Soon you can't put up a satellite without it being shredded by a swarm of junk. To protect against debris, Golden Age warsats are shielded by a kinetic superconductor that transforms a punch into a charge.

Thanks to enemy action, we have a lot of downed warsats. With some tweaking, we can peel out the superconductor and produce a personal defense system. Like so.