temp limits for new generator

[Yuma]

Dear all;

If you had to purchase a new generator, - 400 MW, H2 inner cooled - what is the maximum temperature that you would expect to measure at full load? For the windings, assuming class F, in theory you could accept 155 ºC - 15 ºC for hot spot tolerance = 140 ºC... but I have never seen any generator running hotter than 90 ºC as measured by RTD. On the other hand, what would be a safe level of temperature to have in the core, especially in the end of the core, when absorbing reactive power? Are you aware of standards that give values for this? Any ideas will be appreciated.

 

[ScottyUK]

Many designs are insulated for Class F service but designed to run at the Class B limits to ensure long life of the insulation. With Class H and Class 220 materials available it is possible to run at the Class F limits with a similar margin to extend the life of the insulation system. This tends to be a requirement in a client specification rather than something defined in a standard.

 

[edison123]

Operating class F machines at 140 deg C will invariably lead to less life cycle. As Scotty says, class B limit of 120 deg C winding temperature max is the best way to go despite OEM claims of higher temperature limits.

As for the end core heating during mainly VAR loads, it is more the winding temperature that comes into play (due to its temperature limits) than the core temperature itself, which can sustain higher temps.



Muthu

http://www.edison.co.in

 

[Yuma]

Thanks Scotty and Muthu. Yes, you are right, Class F insulation running at Class B temperatures has been a common requirement for other generators we have purchased.
Kind regards