Temperature Derating factor
Temperature Derating factor
(OP)
Hi,
I'm working in a power station where the ambient temperature is close to 55 deg C.What derating factor could be used for the loading of the generators? I know that the best way to obtain the derating factor is from the supplier but the generators are very old stuffs and I'm looking for a reasonable factor.I presume a ten degree rise in working temperature is considerable.The generators are of 5000 kVA size.
Guardiano
I'm working in a power station where the ambient temperature is close to 55 deg C.What derating factor could be used for the loading of the generators? I know that the best way to obtain the derating factor is from the supplier but the generators are very old stuffs and I'm looking for a reasonable factor.I presume a ten degree rise in working temperature is considerable.The generators are of 5000 kVA size.
Guardiano





RE: Temperature Derating factor
Is the generator air-cooled?
David Castor
www.cvoes.com
RE: Temperature Derating factor
Assuming that the old windings are of class B insulation, 120 degrees C would be the maximum operating temperature according to most standards. Therefore, at 40 degrees C ambient the permissible temperature rise would be 80 K. If the ambient temperature is 55 degrees C, then the maximum operating temperature still is 120 degrees C but the permissible temperature rise would be 65 K only. Make sure that site elevation is less than 1000 metres above sea level, otherwise the temperatures mentioned above have to be reduced.
Wolf
www.hydropower-consult.com
RE: Temperature Derating factor
David Castor
www.cvoes.com
RE: Temperature Derating factor
I agree with wolf39 that you will probably find that you have a Class B insulation which allows a stator temperature of 120C. This corresponds to 40C ambient + 80C rise.
If you have RTD's (dpc's question) then you can determine if your generator is running too hot.