[Amps] Benefits of 3-phase power?

[kayser at sympatico.ca]

Roger:

However,
> the power line to this area is single phase 7.2kV and
> at least 20km long. And it appears to work quite fine!

Yes certainly and the other two phases of that 7.2 kV line are 
off in other directions serving other areas around you.

There are only two single phase high voltage distribution areas
left in Ontario as I remember from a presentation I attended some
time back.  The first is the 25 cycle single phase high voltage from Great Lakes Power at Sault St. Marie to Algoma Steel (they use the stuff for making steel) and the other is a somewhat messy single phase 60 cycle arrangement at Wawa that makes the steel pellets for Algoma Steel.  

Three phase has the best benefits for electric motors at high power and for major loads such as the broadcast FM transmitter I run over in Belleville.  

There are no single phase plants that are part of our dearly beloved Hydro One. 
> I feel that history, and decisions made 100 years ago,
> have much to do with power distribution systems - I
> would be surprised if 120V would be the standard here
> if one could start with a clean slate. 

There is in some ways a genius in the 110/220 decision so many years ago.  The economics of cheap copper here in North America were a direct contribution to that early decision.  The hard part is the creep that has taken us to 120/240 and the impact it is having on older motor designs (excess heat) of which there are apparently over 100K units of 110 V motors still in use in Ontario alone.  

> 
> One thing I found I could not live with was a 120V
> electric kettle

Yes, I agree, I really enjoyed the same units I saw in Eastern Europe when I was there a few years ago.  

Larry
VA3LK / WA3ZIA