Power Transformer Rating

[CuriousElectron]

Greetings,
What determines whether we go with single forced cooled rating, or natural cooling/first stage cooling/second stage cooling for oil filled, power transformers above 100MVA rating?
Is this evaluation based on engineering judgement/industry best practices, or?
Thanks,
EE

 

[waross]

Designed for anticipated load growth.
Actual rating depends on installed equipment.
Selection of operating cooling mode by thermostat(s).

 

[CuriousElectron]

What if this is a GSU transformer sizing exercise for a big generator? Would you match the GSU rating to Generator rating but provide a bit more MVA capacity on the GSU to account for any future unit uprate as a result of a unit rewind and to compensate for higher-than-average summer temperatures?
Thanks,
EE

 

[System Protection]

What if this is a GSU transformer sizing exercise for a big generator? Would you match the GSU rating to Generator rating but provide a bit more MVA capacity on the GSU to account for any future unit uprate as a result of a unit rewind and to compensate for higher-than-average summer temperatures?
Thanks,
EE

Yes, but I would also look into transformer operating temperature vs longevity.

Could be more economical to run a larger transformer at less than max capacity vs a running a smaller one at 100% rating.

There are papers on sizing transformers (economically). Not sure if there is one specific to GSUs.