During a very brief power interruption (brown out) the expansion of gas in the compressor can start moving the rotor in reverse. If power is applied during that rotation it is possible for the motor to start running backwards until it overheats and it can do damage to the scroll. It can't pump so the motor isn't cooled by the suction vapor anymore. I had heard that Copeland fixed this issue at some point, but I still see it on equipement built in the last 5 years. For the record, I have only seen this happen to Copeland scrolls.