Generator continuously at partial load
Generator continuously at partial load
(OP)
Hello,
I have a question regarding a synchronous AC generator (pilot exciter type) driven by a turbine, the generator is rated/sized for 60 MW but will happen to operate most of the time (about 95% of the year) at 35% of it rated capacity (approx 20 MW).
The question is what are the consequences in terms of :
- efficiency
- lifetime, premature failure of electrical and mechanical components, mechanical issues
- overheating
- others?
Fron view point of good/sound enginering practices and codes are there any objections to proceed with such design ?
thanks in advance.
I have a question regarding a synchronous AC generator (pilot exciter type) driven by a turbine, the generator is rated/sized for 60 MW but will happen to operate most of the time (about 95% of the year) at 35% of it rated capacity (approx 20 MW).
The question is what are the consequences in terms of :
- efficiency
- lifetime, premature failure of electrical and mechanical components, mechanical issues
- overheating
- others?
Fron view point of good/sound enginering practices and codes are there any objections to proceed with such design ?
thanks in advance.





RE: Generator continuously at partial load
There are no objections to operating an electric generator at low load that I know.
There is also the prime mover. If it were reciprocating combustion engine it might not like operating at low load. Steam turbines not a problem. Not sure about gas turbines. If you are concerned about the prime mover perhaps give more details.
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(2B)+(2B)' ?
RE: Generator continuously at partial load
A steam prime mover will be probably ok at 35% of capability but won't necessarily be happy if load drops further to about 20% or less because of inadequate cooling and premature condensate drop-out in the final stages of the LP turbine. A diesel will not operate well at 35% load. A gas turbine will be well below its full-load efficiency, and if you use the exhaust to raise steam the HRSG will struggle without auxiliary firing, which will further decrease the efficiency.
RE: Generator continuously at partial load
RE: Generator continuously at partial load
Bill
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"Why not the best?"
Jimmy Carter
RE: Generator continuously at partial load
What speed does your alternator rotate at?
Salient pole or smooth rotor? For salient pole machines windage losses become a significant portion of total input energy at that low a loading...
And I wouldn't drop the prime mover considerations that quickly...
What's the prime mover?
Plus, nobody mentioned hydraulic turbines...
Pelton wheel machines would likely still be very efficient at 1/3 of rated load.
Francis turbines could and probably would suffer significant cavitation damage at that loading; so would Kaplans...and due to having to have their scroll cases vented they would likely exhibit poor efficiency / utilization of water. Deriaz units would probably be fine.
RE: Generator continuously at partial load