Afer finishing our rounds we were in the control room talking when the phone rang, it was the security guard at the switchyard he was hysterical. So the shift supervisor told us to get out there and see what was going on. when we got to the switchyard the guard was out of his mind, saying they were going to get him. We asked him who? He pointed to the transmission lines and said them! We looked and there two black UFO'S floating over the power lines, I asked the other operator with me if he could see them, he said yes we wathed them for maybe five minutes or less and went back the controll room, and took the security guard back with us.