I came across these near the end of the Grissom Academy mission. What exactly are they for? In the screenshot, you can see that they are destructible and you can shoot them. However, after you destroy them, you can "Reactivate" them and the attached Shield Pylon pops on again.
The battle here is a bit too hectic for me to stop and experiment with them (lots of Cerberus and an Atlas mech), so I've just been destroying them outright. I thought that destroying them may act like a pseudo-Overload, but the Turret next to one I just destroyed didn't seem to take any Shield damage.
Do they shield NPCs in an area around them? What exactly should I do with these? Is there any point to reactivating them?
Best Answer
Cerberus deploys T-shaped barriers on the battlefield that form an orange shield wall that its agents can take cover behind, as you can see in the following screenshot taken from this IGN walkthrough video (will contain spoilers, just linked for attribution):
Taking out the shield generator will disable these barriers, immediately exposing the enemies behind them. There's also a sizable explosion which, as LessPop_MoreFizz mentions, can do significant damage to those unfortunate enough to get caught in the blast. Once the area's clear, you can move in and use the reactivation functionality to raise the barriers for your own protection.
Likewise, the barrier pylon to the left of your screenshot encases nearby individuals in their own personal barrier. It's usually a good idea to take these out as quickly as possible, to make dealing with enemies within its effective radius a bit easier.