23 May
2009
23 May
'09
4:25 p.m.
On Fri, 22 May 2009 15:14:19 -0500 (CDT)
Doc <doc at vaxen.net> wrote:
When the RA60 started spooling up he started looking
at it sort of
funny (they wind up like a jet turbine if you never heard one).
Once I listened to
the startup of the 400 Hz motor-generator at
http://www.cray-cyber.org/
The thing needs 400 V three phase and at startup (about one minute)
it draws a current of 120 A. That is 83 kW. 83 kW just to power on the
"PSU" of a single computer. Quite impressive sound.
Several years ago a friend asked me "Is this sound normal?".
He switched on a PeeCee with an old Seagate 5.25" FH SCSI disk. (It was
at a time when 3.5" disks where common.) Typical spin up sound and when
nominal RPM was reached: "BING!" A sound like someone had hit a disk
plater with a hammer. I just pointed to the big solenoid on the drive
and explained that this was the head-lock mechanism... Big eyes staring
into my face and: "You are kidding?" He just couldn't belive...
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/