From Halopedia, the Halo wiki
The energy disruptor is a UNSC device that was reverse engineered from the Covenant-designed power drain device. It deactivates both standard electronics and the plasma-based weapons and energy shielding of the Covenant which have been noted to be very sturdy pieces of technology by UNSC soldiers.
It seems to be easily blocked by walls, as the SPARTAN-III Jonah-B283 waited just outside a Covenant barracks while using an energy disruptor; though the Covenant troops inside were affected, his armor remained intact.
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