Fire at a generator of a power plant

The compressor-turbine unit tripped while on on-load, due to a serious fire between alternator and one of the bearing. The failure of a generator slip ring and of the hydrogen seal caused the leak of hydrogen. The hydrogen ignited (perhaps caused by contact with hot surface), resulting in a combination of hydrogen and oil fires.
The fire extinguished by fire brigade. No injuries.
Serious site damage was sustained to in CT chamber and alternator end of generator.

The INITIATING cause was the hydrogen seal and of the generator slip ring. The source identified the failure of the seal as "caused by circulating current", what unfortunately is not clear.
Nothing can be said on the root cause

bearing, alternator,
turbine-generator system,
oil lubrication system,
hydrogen coolant seal

The plant fire fighters service were the first to intervene with 2 water and foam extinguishing vehicles and 1 ambulance. They carried out a reconnaissance of the area in conjunction with the supervisor on site, cut the electricity supply to the whole section and took the first steps to extinguish the fire.
Access to the area was restricted and the safety zone (300 meters) delimited. Access routes were established to facilitate the access of external intervention forces.
Air quality monitoring in the vicinity of the site was requested to an accredited laboratory. Personnel who were not involved in the intervention were evacuated.
Following the activation of the Red Intervention Plan, the professional emergency service were alerted and directed to the scene of the accident. They arrived from various location I the county.
The fire was extinguished 3 hours later.