At 04:08 PM 12/14/04 -0800, you wrote:
>
>>From: "William Donzelli" <aw288_at_osfn.org>
>>
>>> Reminds me. The CDC Cyber 960 from http://www.cray-cyber.org/ runs at
>>> 400 Hz. The higher frequency allows smaller transformers.
>>
>>I think the intent was to reduce the ripple, rather than reduce the
>>weight. CDC wasn't afraid of a few more pounds.
>>
>>> The 400 Hz three phase current is generated by a motor-generator. The
>>> rotating mass of this machine is enough to keep the Cyber running for
>>> some seconds. (Power consumption of the Cyber at minimal configuration
>>> is around 20 kW.) Enough to start a big diesel generator in case of a
>>> power outage.
>>
>>I doubt you could start a big diesel that fast, reliably.
>>
>>The inertia would, however, protect against little dips and burps in the
>>power, when the utilities are fooling around with the grid.
>>
>
>Hi William
> I was right next to a flywheel started no-break diesel.
>It was running at full load in about one second from
>a complete stand still. My heart was pounding quite hard
>from the adrenaline rush I got. Another way to start
>a diesel fast is with compressed air.
> In anycase, "Yes", they can start that fast.
>Dwight
>
My father told me that when he was in the USAF they had generators that
they called Might-Mites. He said that they had a big flywheel and a
motor-generator connected together and a dieal engine connected via a
clutch. Normally it used AC power to drive the motor-generator and flywheel
but when they lost Ac power a relay closed that caused the unit to dump the
clutch and that instantly engaged the engine. The engine went from 0 to
full speed in a fraction of a revolution. It of course started and then
provided power to operate the motor-generator. Those never lost power
because the motor-generator never stopped rotating even during the split
second between the time they lost AC power and the time the engine started.
he said they worked very well. My only comment is that they must have had a
GOOD clutch and a dammed strong crankshaft.
Joe
Received on Wed Dec 15 2004 - 08:45:50 GMT