Hi Bob:
Thanks for your further explanation.
In North America, three-phase is supplied to
commercial and industrial buildings, 120/208.
These installations are very similar to the
residential installations in Europe.
The primary side of the 120/240 single-phase
distribution transformer is across one leg
of a three-phase higher voltage system.
Most residential distribution transformers
supply up to 8 houses in close proximity.
In rural areas, where houses are widely
separated, it is not uncommon to see a
single pole-pig distribution transformer
supply one house.
Best regards,
Rich
-----Original Message-----
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Robert
Johnson
Sent: Monday, July 20, 2009 1:10 PM
To: emc-p...@ieee.org
Subject: Re: Normal power supply Sweden & Norway]
-------- Original Message --------
Subject: Re: Normal power supply Sweden & Norway
List-Post: emc-pstc@listserv.ieee.org
List-Post: emc-pstc@listserv.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Mon, 20 Jul 2009 16:08:49 -0400
From: Robert Johnson <john...@itesafety.com> <mailto:john...@itesafety.com>
Reply-To: john...@itesafety.com
Organization: ITE Safety
To: 'Rich Nute' <rn...@san.rr.com> <mailto:rn...@san.rr.com>
References: <F0CDD9B9E06747A883C7A0B1A3BC9592@PC323541548743>
In Europe, there has been much more integration of business and
residential
areas. Businesses, due to higher loads and motor loads, find 3 phase
important. In addition, transformers are likely to serve a larger geographic
area in Europe due to the lower current/higher voltage, thus more likely to
span a mixed zone. Three phase is far more efficient at distributing power
than single phase. Adding a third wire triples the power delivered.
In the US residential areas are often far removed from businesses and
are
characterized by single phase loads. Lots of rural areas are served only with
a single phase (sometimes in the past even a single wire with a ground return)
and thus an expectation of single phase service has developed. Distribution
starts with three phase but thins to single phase when the loads are light and
spread out. No one here would dare to produce a residential three phase
appliance.
The 120/240 volt service developed from a 120 volt service to serve
larger
loads since it is easy to derive from a single phase feed, will deliver twice
the power at the same current and still provide for 120 volt loads.
'Rich Nute' wrote:
Hi Ralph:
Is it common throughout Europe to distribute 3-phase power to
single-family
homes?
Well, yes. I'm not sure of England.
If so, why are single-family and duplex residences in North
America
supplied with 120/240V single-phase?
I'm sorry, but I can't answer the question.
Best regards,
Rich
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