Fire on a generator of a power plant

Gaseous hydrogen release in generator caused by turbine vibrations

The INITIATING CAUSE was mechanical vibration of the turbine causing the disruption of the oil seal of the hydrogen coolant system.
The turbine vibrations could have been caused by various causes, not reported by the source.

Turbine, hydrogen storage

Hydrogen gas is the preferred coolant to transfer heat from the power generating winding enclosure to the heat exchanges known as H2 coolers. The reason is the heat transfer capacity of hydrogen, much higher than any other solution, resulting in less friction losses and more fuel-to-electricity conversion efficiency than, for example, air. This is particularly true for power generators above the 100 MW. The sealing of hydrogen in the rotating parts occurs by oil sealing.

This incident regards the disruption of the dynamic sealing of the cooling system of the turbine due to vibrations. This is a common failure mode in power plants. It is a secondary (escalation) accidental event of turbine/compressor malfunctioning cases. Hydrogen is then released into the turbine hall. Despite effort in ensuring spark-free equipment inside the turbine hall, arcs and other similar phenomena cannot obviously be excluded from the generator itself.