On Wed, 4 Feb 2004, Chimpsarecute wrote: > ... > In Germany, ... > > In the US, the 3 phases on the pole are at 13.5 kV line to line...
Not true. In the US, three phase transformers are found only at "substations" on concrete, surrounded by wire fences.
A maximum of three or four houses are served by one *single phase* transformer "on the pole" or, in newer housing developments, by a single phase transformer mounted inside a steel enclosure sitting on the ground and connected by underground single-phase cables.
I'm no expert, but I do not think either of these is entirely correct, unless this is ONLY about residential areas.
Many industrial plants (such as the one my office is in) receive 3 phase power. The power coming to the pole outside is 4800 volt, 3 phase. There are three transformers on the pole, and they deliver 206 volt, 3 phase to the building.
When we bought a 480 volt, 3 phase piece of equipment, it was cheaper to buy step-up transformers to get from 206 to 480 in the building, than to have the power company install another set of transformers outside to deliver 480 volts to the building.
Of course, if the 480-volt equipment used enough power, we could not have done that, and would have to have gone to the power company.
Also, I know that transmission lines come in a variety of voltages, ranging from 115 volt for older residential areas, to 780 volt, to 4800 volt, etc.
Jim
Jim Elwell [EMAIL PROTECTED] 801-466-8770 www.qsicorp.com
