Yes, quite a few places operate under the premise that the supply voltage
(ie: the secondary of distribution transformers) is completely or nearly
floating.

This has the advantage that a single fault will not cause a problem.

One example I know of where this was used was in a factory that used a lot
of power. Rather than ground one side of everything it was all kept
floating, and a light bulb was connected from each phase to ground. Under
normal circumstances the three bulbs would all burn dimly. If one of the
phases happened to short to ground, the corresponding bulb would go out, and
the plant electrician could start trying to figure out what went wrong - and
meanwhile the plant could continue to run. Of course, if a second phase
shorted to ground then fuses/circuit breakers would come into play.

btw: the auditorium lighting in my high school used the same trick by using
three LARGE transformers to step about 3000v down to an ungrounded delta
connection with 120v from leg-to-leg (truly an odd way of doing things).
This was the way they did it in the early 1900's when the auditorium was
built.

Bob Ammerman
RAm Systems



----- Original Message -----
From: "Francisco Ares" <francisco.a@ALTEC.COM.BR>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, February 22, 2002 4:46 AM
Subject: Re: [EE]: Power in Russia?


> Please, do not take it for granted: I have already measured 80V from
> neutral to ground in some places in my country.  Low current capable,
> but still feel not willing to touch it ;-)
>
> Francisco
>
>
> Vasile Surducan wrote:
>
> >Harold, the neutral is grounded all over the world !
> >But your ideea about don't fusing neutral is wrong because this ground
> >connection is done near the transformer and some time there are long
> >distances through user to transformer. This means a lot of dropout
voltage
> >on the neutral.
> >Also fusing neutral is not only for short circuits to phase but also for
> >high currents in that phase/neutral circuit.
> >About 20A on one phase is too much, you'll overbalance the system. The
max
> >admitted current for one phase system is 9...10 A.
> >
> >Now you'll check if your device is right projected. [big grin]
> > ( east european and russian mains have 220V +20% -15% running at 45...50
Hz.
> >Success, Vasile
> >
> >
> >
> >
> >On Thu, 21 Feb 2002, Harold M Hallikainen wrote:
> >
> >>        I have a customer wanting to use our equipment in Russia. They'd
be
> >>using a single phase 20A circuit. I understand they use 230V, 50 Hz. Do
> >>they have a grouned neutral, as we do here in the US? In the US, we rely
> >>on the neutral being grounded, so we don't fuse it (since a neutral
short
> >>to ground does not create a fire hazard). So, what is the power
> >>configuration in Russia? Anyone aware of a website that shows
> >>schematically electrical standards throughout the world (single and
three
> >>phase, from the final distribution transformer(s) to the customer load,
> >>including standard placement of grounds, fuses, etc)?
> >>
> >>Thanks!
> >>
> >>Harold
> >>
> >>
> >>FCC Rules Online at http://hallikainen.com/FccRules
> >>Lighting control for theatre and television at
http://www.dovesystems.com
> >>
> >>________________________________________________________________
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