Power generators were also used to power the psi disrupter on Braxis. They were only lightly-defended and located a considerable distance from the disrupter. They were destroyed by Raynor's Raiders, cutting the disrupter's power.
Power generators were special buildings in missions and could not be built by SCVs. They could be inserted into custom maps via StarEdit.
Power generators are also the only known terran structures having no fire animation when damaged, though they gradually decrease in health like all other terran buildings when the hitpoints are in the red.