A 1940's 1KW rotating stator AC generator. Incandescent and dimmable lights flicker on it. This was part of an investigation in the source of that flicker.
One of the AC slip ring brushes is streaking the slip ring. This video was to observe the brushes under load. It was filmed with a GoPro Hero4 Black at 240 FPS, and this upload is slowed to 30 FPS without pitch shifting, so all audio is lowered 3 octaves and 8 times longer.
The background noise (lowered 3 octaves) are mainly 3 sounds:
1. Exhaust whoosh
2. clicking of the exhaust valve then intake valve closing
3. ball bearing whine
The nearest slip ring has over an hour of 7 Amp (800 watt) resistive-load run time after polishing and is still very clean, while the further slip ring has less than 5 minutes. It appears some slight remaining pitting in a low spot on that ring is causing dark streaking. The eccentricity of each slip ring is about the same, as evidenced by the brush displacement. The DC side generator commutator was polished and seems to be fine.
Generator: 4 HP Wisconsin ABS engine at 1800 RPM driving a Master generator.
