It is usually said that the steam turbine generators are designed to match the exact capabillty of the turbine. But the capability of the generator in a Gas Turbine system is always shown higher than the Gas turbine at all ambients (Maybe 5% or 10%).

Which standard IEEE/IEC says that the generator capabilty has to be higher than that of a Gas Turbine and by what percentage?

Any help will be highly appreciated!
abhayambuj @ hotmail. com

 

Economics would be a measure for generator output.

If the turbine will be located at a latitude when inlet temps are generally low, a larger generator output capacity would be needed.

On the other hand; If the turbine is located at a latitude where inlet temps are generally high, it is not economical to purchase a generator where the higher turbine outputs will never be reached.

For instance, A GE Frame 7EA located at a latitude of 39 degrees would need a generator capable of 96MW with average summer output of 70MW and winter output of 93MW.

The same turbine located at a latitude of 65 degrees would need a generator capable of 120MW because it could have sustained operation at over 100MW output.

Steam turbines/generators are sized by the capacity of their steam generators.

Hope this helps.

 

Thanks for the reply, However, I have a specific query for a Gas Turbine to be offered to a particular customer whose latitude does not change and we know the min and max ambient temperatures throught the year. Why do some customers/ consultants ask for Generator capability to be higher than the Gas turbine output. One reason being that they intend to install a chiller in the future which will help in increasing the GT output. But does that mean in the Output curve (Generator output vs. ambeint temperature) that Generator output to be elevated than the GT output at all ambients? Is that specified in some standard? The elevated line is just the maximum capability of the generator (which is fictitious till now).

If this is the case, the customer/consultants ask for generator reactive capability to be drawn corresponding to generator elevated output. Is this the correct practice? When Gas turbine is delivering a output of 70MW How can my reactive capability curve show 96MW output (max output at least ambient)?