Generating stations can handle an immediate loss of load without damage,
and do so regularly.  Although they can handle it, such events are
painstakingly avoided because they are very annoying and very costly.
When such a loss happens, they immediately blow off their steam
reservoir to prevent the generator rotor from over speeding.  I've been
involved in several unplanned shutdowns of this type at a 600 MW coal
fired power plant; two due to operator error, one to a nearby industrial
explosions, and one as the result of a tornado.  The sudden release of
steam generates a roar that will you cause you to shake and/or drop to
the ground.
 
The operator error caused shutdowns were always a case for extreme
chastisement of the offending employee because it would take nearly 8
hours to bring the unit back on line with a total restart cost and
loss-of-revenue cost of approximately $100,000.
 
M Peterson
 
 
<snip>
But ,then, if everything is "off", who cares?.
 
Well, we should care. The results of the above condition could be very
dangerous for the generators because lots of them would get tripped down
and a trip condition most of the times  generate new problems along with
the original one. I.E., a trip causes an excited generator to open its
field breaker. Often, this condition could make the breakers contacts to
explode. This is not a mjor issue for a single generator, just a matter
of time to change the breaker. But when this happens to a bigger number
of machines we get into trouble. You must take in to account that there
is not always a good stock of replacements when generators are 20 or
more years old.
<snip>
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