The discussion about 3-phase made me check some documentation.
The drive I remembered that uses 3-phase power is the RP04. I remember a
warning to the installer to verify the phase order; if that's wrong the drive
will try to spin up in the wrong direction, which might partially unscrew the
pack from the spindle -- that would be bad if the heads tried to load.
The RP07 is also 3-phase. Other drives I looked at are 1 phase.
I also looked at some CDC 6000 series docs. Those used 400 Hz 3 phase for
supplying the CPU and peripheral logic. The CPU cabinets also take 3 phase
mains power for the compressors (for the Freon cooling system). Curiously,
the 1964-era 6603 disk drive uses only 400 Hz power. I wonder if that feeds
the spindle motor, or if that was a DC motor? And the 626 tape drive wants
3-phase mains power.
paul
