Some of the earliest power distribution systems in British cities were indeed 3-wire Edison-type arrangements, 100/200V to 125/250V D.C. Many of them were then upgraded to double the voltage, and the 200/400 to 250/500V 3-wire D.C. systems survived in the older parts of some cities well into the 1950s (with a normal residential service taking just a 2-wire supply from one "hot" and the neutral).
It's noteworthy that the argument of overhead vs. underground distribution is still going on over a century later, at least in some places, There are plenty of people today who would like to see all cables placed underground, but they just don't realize how much more expensive that would be.
It's noticable even to the casual observer though how fewer overhead cables we have in a typical British town compared to a typical American town.
[This message has been edited by pauluk (edited 05-24-2006).]
Re: Electric Lighting in 1890#145448 05/24/0606:16 AM05/24/0606:16 AM
I once heard the 110 and 220 Volts were derived from arc lights - supposedly the minimum voltage for arc lights is 55V, and they wired 2 or 4 of them in series to reduce voltage drop.
Yep, Texas Ranger you are correct.
The 110 and 220 Volts were derived from the 55 volts arc lamps in series. To reduce the current from 2 or 4 lamps in parallel the series option was chosen and still remained within the limits of the available insulation materials for cables of those days.
Streetlighting was sometimes done on higher voltages as quoted in the article but mostly supplied via catenary wires which were strung on insulators hence a higher voltage was used.
Also the carbon filament, wolfram or early ediswan lamps didn't like the higher than 110 volts voltages and tended to burn out to fast.
Putting everything underground, great ! , but costs are high. Even now these days overhead is more cost effective in rural area's anyway and is not subjected to damage by ground movement or directional drilling.
The product of rotation, excitation and flux produces electricty.
Re: Electric Lighting in 1890#145449 05/24/0612:25 PM05/24/0612:25 PM
Thanks everyone! I was wondering where the 110-120 standard came from. I didn't know that this came from earlier arc lighting. Some sources mention that the US went to 120 V by the 1930s when light bulbs were improved enough to handle it.
If that wasn't enough, there were different arc lights on the market. They required slightly different voltages, somewhere in the 40-55 V range, and were normally wired in pairs to match a grid voltage of 80-110V.
I've heard that the first generator Edison got hold of put out about 110V which makes perfect sense: About 100V to run the arc lights and a little more for the voltage drop in the cables. Edisons real innovation was to design a bulb that ran on this voltage for extended periods of time.
Bulb that ran on a low voltage, like 20V, for a brief time did exist. But what use is such a thing?