Derating factor on Gas turbine + Generator

[NickParker]

Gas Turbine + Generator sizing:
A derating factor of 3.5% is put on top of the guaranteed electrical output from the Generator terminal for the ageing and fouling effects.
I'm not aware of the any standard from where this derating factor arise? I have checked API 616 and API 546 but could not find this requirement of derating factor.

Can anyone shed some light on this?

 

[Hoxton123]

Which entity gave the derating statement?

 

[RRaghunath]

The derating factors you mentioned are to do with Gas Turbine and the associated air Compressor.
May be, ISO or the Gas turbine manuals would be appropriate to refer I suppose.

 

[LittleInch]

Unlikely to be a code or published standard issue, but one in which the vendor is applying years of experience of their own machines.

But provide a few more details and answer the questions above and it might be clearer.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.