VAX 6000 3-phase conversion (was: Re: Three Phase)

From: Robert F Schaefer <rschaefe_at_gcfn.org>
Date: Sat Apr 21 12:44:36 2001

On Sat, 21 Apr 2001, Clint Wolff (VAX collector) wrote:

>
>
> On Sat, 21 Apr 2001 jkunz_at_unixag-kl.fh-kl.de wrote:
>
> > Protective ground is identical to N. It is only an extra wire to the N
> > point. This is needed for protection only. (Therefore it is called
> > protective ground. ;-) )
>
> Some clarification is in order...
>
> Protective ground is NOT identical to N, even if they are wired together
> at the main breaker panel (as in USA). Neutral is a current carrying
> conductor, and because of the resistance in the wire, it may be at some
> voltage above ground potential. This is why you NEVER attach the
> neutral to the protective ground.

What he said!

>
> Remember: if there is any possibility of current flow, use the Neutral
> wire.

The only purpose of the green (ground) wire is to help the overcurrent
device operate-- it is there to make what might be a small leakage to an
electrically isolated chassis into a large fault to ground.

>
> Remember: Always connect the protective ground to the chassis of the
> machine.

Do this, and also connect the other end... (Also, in the US, the old
three-prong dryer & range cords are illegal now. Be sure and use a proper
cordset, that provides an equipment ground)

>
> These voltage are high enough you can destroy valuable antique hardware,
> which would be bad. You might get shocked too...

in that order...

>
> clint

Bob
Received on Sat Apr 21 2001 - 12:44:36 BST