In a message dated 9/10/2011 4:20:14 P.M. Eastern Daylight Time,
edmiston@bluffton.edu writes:
John D. said...
You might hope to get by with just a huge valve to allow steam
to bypass the turbine, but in practice I doubt it is that simple.
In this business, details matter.
I ask...
If this is not what happens now, then what does happen now? If the
generator load disappears suddenly, and the reactor can't cool down
suddenly, and there aren't valves to divert the steam around the turbine,
then why doesn't the turbine speed up to a much higher rotational speed
that would seem likely to cause mechanical damage? Surely there is not a
mechanical brake that can dissipate 1000 MW. So what is the current
practice for shutdown when a sudden disconnect from the grid is required?
)))))))))))))))))))))))))))))))))))
The steam valves slam shut at high speed and there are steam dumps to
bypass some load, the amount varies from plant to plant. On a turbine trip when
you still have a grid you trip the steam valves but keep the generator
breakers closed until the reverse power relay trips these breakers open. This
uses the grid to hold turbine speed. When these big values trip you don't
want to be close by , you will need to change your underwear if you are.