Hydrogen Cooling of Alternators


The alternator in the large power plant consists of conductor with high electrical current flowing through them, which generates large amount of heat. If this heat is not dissipate in the surrounding area, alternator winding can quickly degrade and eventually damaged. When selecting cooling gas of alternator, several points to be considered.

  • Minimizing drag due to coolant gas ( windage losses )
  • Maximize alternator output by optimizing heat transfer
  • Safe operation

The air or water cooled alternator have been widely utilized up to 100 MW, but the efficiency of alternator tend to fall beyond 100 MW, in such a condition hydrogen is used as coolant gas.

Advantages of hydrogen as coolant gas

  • It offers low drag coefficient due to low density of hydrogen.
  • It has highest thermal conductivity of any gas.
  • The hydrogen gas is easy to manage,  as it is not easily mixed with pure CO2.
  • It is inexpensive, as compared to other low density gases.


  • It is explosive when mixed with air.

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