trianglar ufo, hoverd above a power-station,

i saw with my uncle, A ufo hoverd above a power-station,it was there for about 10min,,there was no sound coming from the ufo it came from the west then headed towards the east, i also saw lights from each corner of the craft,,And had a light in the middle of the craft ,but the lights wasent on for to long..the craft was a dark colour.it seemed to have like a low hum sound to the craft, but it was a very low hum, you could just make it out (the sound)..