Hydrogen dew point in power generators

[abolfazlghasemi]

Large power generators (for example 200 MW) are cooled by H2 in gas form. H2 temperature is +45 to +75 "C. So why hydrogen dew point is important in generator while the lowest hydrogen temperature is 45 "C? And in some Power Stations is monitored online...
Thanks, a lot

 

[Lnewqban]

Welcome @abolfazlghasemi !

Hydrogen is an excellent cooling agent, but is highly explosive when mixed with air.
For that reason is very important to keep both separate.
Some atmospheric humid air can still slowly leak into the hydrogen occupied volumes.
Since it normally contains some water vapor diluted in it (absolute humidity), monitoring the dew point of the hydrogen can tell how much air contamination has happened and how closer to an explosive mix it has become.

Please, see:
https://greenrenpower.com.au/products-and-services/electrolysers/how-h2-cools-generators/

https://able.co.uk/media/2015/08/re...ment-for-electricity-generator-protection.pdf

 

[Windadct]

I had always understood the varnish winding to be pretty hydrosopic - the issue is not dew point, but total moisture in the system. Dew point is easier to measure and monitor. BUt similarly - I could see it being easier to maesure Dew point then O2 as well - but it would have less correlation.