VAX Cluster on Ebay in OK (was Re: More DEC equipment spottedin

From: Patrick Finnegan <>
Date: Mon May 3 23:01:19 2004

On Monday 03 May 2004 22:14, Tony Duell wrote:
> > 208 is really a 240 volt 3 phase system measured in a star
> Is it? I'd assumed it was 120V neutral-phase, which is then 208V
> phase-phase.

Tony is right here. At least in Indiana, Illinois, and the Code Book,
208 three-phase is a "Y" setup with 120V from each phase to neutral,
and 208V from phase to phase. 240V three-phase is a delta setup, with
the neutral half-tapped between two phases, giving 240V phase-to-phase,
120V phase-to-neutral on two of the phases, and 208V phase-to-neutral
on the third one. It's important to realize when wiring a system like
this that the third phase is NOT 120V to neutral like the other two,
I've heard of some people (idiots) ignoring that, and having issues
when they tried to turn on their 120V lamps they just wired. : )

> > I have not looked at any 3 phase power supplies for computers, but
> > I would bet they are 240 volt 4 wire and don't bother with the
> > neutral at all, just 3 phases and a ground.
> Not at all. A very few PSUs are genuinely 3-phase, and some large
> disk drives have 3 phase motors. But in the case of DEC machines at
> least, the individual PSUs are single-phase units run between a phase
> and neutral (star connected). Of ocurse the load is approximately
> balanced between the 3 phases (or it is if the machine is configured
> properly).


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Received on Mon May 03 2004 - 23:01:19 BST

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