Running 3 phase 780s on single phase power (was RE: hams on classiccmp)

[Paul Koning]

>>>>> "Ian" == Ian King <IanK at vulcan.com> writes:

 Ian> Um, let's clarify something: there are NO three-phase components
 Ian> in a VAX-11.  The switchers, the fans, ALL of it are single
 Ian> phase.  Oh, there is one component that's "three phase": the
 Ian> power supply in the PDU itself, which generates the voltage to
 Ian> run the relay that switches the switched outlets.  That's fused
 Ian> separately.  And yes, the neutral leg has a breaker, too.

 Ian> And yes, this IS a "full config", with RH780, DW780, CI780 and
 Ian> (lucky us!) FP785.

Some peripherals are real three phase, though; the RP06 comes to mind.

A breaker in a neutral is odd.  I guess it's legal IF it's part of a
set of tied-together breakers, so that tripping the neutral breaker
also opens the phases.

I wonder why they didn't use 3-phase power supplies; that would save
space for the filter capacitors.

     paul