On Tue, 22 May 2001, Gunther Schadow wrote:

<snip>
> 
> > Start at the front end of the 300v supply (the long skinny one)
> > Where the mains feeds into that is the first port of call, I'm assuming
> > the
> > switchgear box is ok, since it ran that long.  My bet is that leaving
> > the neutral
> > off may be the cause of the problem, and it's likely to be confined to
> > the input
> > side of the 300vDC supply box.
> 
> > I do, unfortunately, it's on a 240vac SINGLE phase circuit.  The 110v
> > 220v 2 phase issue.
> 
> So, what did you do with neutral? With a single phase you probably
> hooked neutral to L1 (2 or 3) and the one phase to L2 (3 or 1). Then
> you did not connect the 4th neutral wire, I mean the real neutral
> in the sense of the 3-phase world, the X-axis around which the three
> phases undulate? So effectively you have you null open too, or don't
> you? I would appreciate to know exactly what you did. Was that detail
> on your web site?

On my 6310, the neutral never makes it to the 300V power supply-- it's
strictly for the 120V recepticals on the power distribution box.  Nothing
plugged in to this box will operate properly without it except the 300V
PS.

> 
> > What is the ACTIVE to NEUTRAL voltage on your dryer circuit?
> > This could be an undervoltage condition.  The 300v supply needs around
> > 220v to operate, much under this might cause higher than usual currents
> > to be drawn.
> 
> Ah, higher current doesn't sound good. So you say an undervoltage
> could cause a component to blow up? That would be consistent with
> what happened. But isn't power (P = U x I) what fries components 
> rather than higher current at lower voltage? I'm not necessarily 
> confident in my judgement here, but I wonder.

High anything isn't that good.  However, the current that would be drawn
from a 220V single-phase service is IIRC just about 10% higher than what
would be drawn from a 120/208V three phase service.  I would imagine that
that's close enough to within specs that reliability would not be
significantly affected.

> 
> > > I still hope the machine isn't lost
> > 
> > Unlikely to be fatal, any problems are almost certainly confined to the
> > power supply, and specifically,
> > almost certainly to the 300v DC supply.
> 
> I have a spare one which isn't necessarily good either (that 
> came out of a machine that was *known* to have similar power 
> problems (i.e. shutdown after 15 minutes). I am hesitant to 
> throw in the other box, but will do so if I can confirm that 
> I made a mistake with the hookup and once I understand how to 
> avoid a similar mistake. Here is again what I did:
> 
> Black -----------------+------ P1
>                       /         |
> Black ---------------+        ~230V
>                                 |
> Brown ------------------------ P2
> 
> Blue ----------(open)
> 
> Green/Yellow---(open)

This looks Ok, except for the grounding (you really need this for
safety!!) and you'll need the neutral if anything else is plugged into the
power box other than the 300V power supply.  No reason that I cna see why
it wouldn't work.

> 
> > > but everything is now
> > > much harder.
> > 
> > Not that much, but you need to sort the mains feed out as a priority.
> > 
> > Cheers
> 
> Indeed, Geoff, you cheered me up, giving me hope!
> 
> thanks,
> -Gunther

Bob