[LINK] BPL

[Bernard Robertson-Dunn]

Pilcher, Fred wrote:
> Sorry, a little off-topic, but related...
>
> Robin wrote: 
>
>   
>> It is difficult or 
>> impossible to make worldwide standards since the powerline 
>> distribution structure in the USA and other 110 to 120V 
>> countries is completely different to that in the 220 to 240 
>> volt countries.
>>     
>
> Does anyone know why the US chose 110-120V where most of the rest of the
> world chose 220-240V?
>
> Was it just a case of choices made when the infrastructure was young as
> opposed to a later start with more time to consider, or was there a
> technical reason?
>   

First, the higher the voltage the lower the resistance related power 
losses in distribution.

AC is better than DC because AC permits the use of transformers to 
change voltage levels.

Three phase is better than single phase because it uses much less metal 
in the transmission system.

Edison in the USA originally selected 100/110 volts DC because that was 
a good compromise between distribution costs and lamp costs (of the day) 
and AC was seen as being less safe. The distribution system was 110 
volts DC but the lamps were rated at 100 volts. The missing 10 volts 
disappeared as heat in the distribution system.

In 1899 a Berlin utility picked 220 volts AC 50 Hz for its distribution 
system to reduce costs.

Europe went with 220 (now 230) volt 50 Hz AC, in the USA Westinghouse 
went to AC 60 Hz (so they could use smaller transformers) but stayed 
with 110v (sort of backwards compatible, 110 volts DC is not the same as 
110 volts RMS).

-- 
 
Regards
brd

Bernard Robertson-Dunn
Canberra Australia
brd at iimetro.com.au