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Home > Archive > Electrical Engineering > June 2006 > origin of voltages (why 120, 240, 440, 6900, 24900 Values)
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origin of voltages (why 120, 240, 440, 6900, 24900 Values)
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| AlvatrozH 2005-09-28, 6:21 am |
| Some of history, Do somebody knows about the origin of the voltages
values used in electricity, why 120 V an not for example 50V or 350 V.
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| AlvatrozH wrote:
> Some of history, Do somebody knows about the origin of the voltages
> values used in electricity, why 120 V an not for example 50V or 350 V.
In 1886, Nikola Tesla discovered a large number of electrical devices rated
for operation at those voltages for sale on EBay. The price was low
because nobody knew how to generate AC power properly in those days.
Tesla bought all of the devices and invented the necessary generating
equipment. And that's what happened.
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| That's silly. They picked those voltages more than 100 years ago based
on one of their back-to-the-future trips!
Roby wrote:
> AlvatrozH wrote:
>
>
>
>
> In 1886, Nikola Tesla discovered a large number of electrical devices rated
> for operation at those voltages for sale on EBay. The price was low
> because nobody knew how to generate AC power properly in those days.
>
> Tesla bought all of the devices and invented the necessary generating
> equipment. And that's what happened.
>
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| > Some of history, Do somebody knows about the origin of the voltages
> values used in electricity, why 120 V an not for example 50V or 350 V.
Look up ANSI standards C-37 and C-84. Those documents may give some
insight into why these particular voltages were selected.
Keep in mind that historically 120V single-phase AC was much lower when
commercial power generation started near the turn of the 20th century.
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| Beachcomber 2005-09-28, 7:21 pm |
| On 28 Sep 2005 13:33:44 -0700, "tlbs" <tlbs101@excite.com> wrote:
>
>Look up ANSI standards C-37 and C-84. Those documents may give some
>insight into why these particular voltages were selected.
>
>Keep in mind that historically 120V single-phase AC was much lower when
>commercial power generation started near the turn of the 20th century.
>
Selection of 110 v. was based on a complex set of requirements which
included what would be optimum for a carbon filament lamp to operate
at the maximum luminous level, give a reasonable long lamp life,
overcome the voltage drop from the dc central station generator (in
use back in the 1870's), provide a certain degree of safety, and
provide design parameters for associated equipment such as fuses,
switches, insulation thickness, etc.
Beachcomber
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| Bob Ferapples 2005-09-29, 3:21 pm |
| On 28 Sep 2005 01:24:16 -0700, "AlvatrozH" <Alvaro.Herbas@gmail.com>
wrote:
>Some of history, Do somebody knows about the origin of the voltages
>values used in electricity, why 120 V an not for example 50V or 350 V.
Because 121, 243, 449, 6932 and 24941 just seemed silly.
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| Michael Moroney 2005-09-29, 11:21 pm |
| I can't give an authorative answer, but I have noticed that many of
the voltages are often either multiples of 120V or 120V times sqrt(3) or
120V/sqrt(3) (~69V). Usually the multipliers are powers of 2, 3 and 10.
Sometimes the "120V" figure is off somewhat. Examples of the first are
480V, 7200V, 345kV (multiple of 115, not 120), voltages like 277V, 69kV and
13,800V are multiples of 120V/sqrt(3). The sqrt(3) falls out of 3 phase
power math. These voltage ratios probably comes from integer winding
ratios in transformers.
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| Gavin Parsons 2005-09-30, 8:21 am |
| 240 people on the committee and half wanted 120 half wanted 240 all except 1
who wanted a beer.
"AlvatrozH" <Alvaro.Herbas@gmail.com> wrote in message
news:1127895856.590928.259820@o13g2000cwo.googlegroups.com...
> Some of history, Do somebody knows about the origin of the voltages
> values used in electricity, why 120 V an not for example 50V or 350 V.
>
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| chuck 2005-09-30, 10:21 am |
| Wasn't it 110 volts at one poin?
Michael Moroney wrote:
> I can't give an authorative answer, but I have noticed that many of
> the voltages are often either multiples of 120V or 120V times sqrt(3) or
> 120V/sqrt(3) (~69V). Usually the multipliers are powers of 2, 3 and 10.
> Sometimes the "120V" figure is off somewhat. Examples of the first are
> 480V, 7200V, 345kV (multiple of 115, not 120), voltages like 277V, 69kV and
> 13,800V are multiples of 120V/sqrt(3). The sqrt(3) falls out of 3 phase
> power math. These voltage ratios probably comes from integer winding
> ratios in transformers.
>
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| Don Kelly 2005-10-01, 1:21 am |
| The beer drinker won as he could pee higher on the wall than the others,
reaching 120cm. You don't hear of him as, after this, he was arrested for
exposure and being a public nuisance.
Don Kelly @shawcross.ca
remove the X to answer
----------------------------
"Gavin Parsons" <gavin.parsons1@ntlworld.com> wrote in message
news:9W8%e.2830$Nv6.1952@newsfe6-win.ntli.net...
> 240 people on the committee and half wanted 120 half wanted 240 all except
> 1 who wanted a beer.
> "AlvatrozH" <Alvaro.Herbas@gmail.com> wrote in message
> news:1127895856.590928.259820@o13g2000cwo.googlegroups.com...
>
>
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| BFoelsch 2005-10-01, 2:21 pm |
|
"chuck" <nospam@nospam.net> wrote in message
news:h9a%e.6447$QE1.226@newsread2.news.atl.earthlink.net...
> Wasn't it 110 volts at one poin?
It was all over the place between 100 and 130 in the earliest days.
In the era of Edison General Electric, when the same company made the whole
system, including the lamps, lots of (to us) strange things occurred.
One issue was the matter of carbon filament lamps. The uniformity of these
lamps was poor, but the lamp life then, as today, was a steep function of
voltage. This posed a major problem in that lamps were not truly
interchangeable. The earliest solution was to sort the lamps into voltage
categories. However, because the lamps and distribution and energy were all
supplied by the same entity, it was not a problem to run one neighborhood or
city at 110 to use up the 110 volt lamps, and another area at 125 to use up
the 125 volt lamps. This practice declined with the advent of better lamps
and was pretty much obsolete by World War One.
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| Beachcomber 2006-06-19, 8:25 pm |
| On Sat, 1 Oct 2005 12:54:46 -0400, "BFoelsch"
<BFoelsch@comcast.ditch.this.net> wrote:
>
>"chuck" <nospam@nospam.net> wrote in message
>news:h9a%e.6447$QE1.226@newsread2.news.atl.earthlink.net...
>
>It was all over the place between 100 and 130 in the earliest days.
>
>In the era of Edison General Electric, when the same company made the whole
>system, including the lamps, lots of (to us) strange things occurred.
>
>One issue was the matter of carbon filament lamps. The uniformity of these
>lamps was poor, but the lamp life then, as today, was a steep function of
>voltage. This posed a major problem in that lamps were not truly
>interchangeable. The earliest solution was to sort the lamps into voltage
>categories. However, because the lamps and distribution and energy were all
>supplied by the same entity, it was not a problem to run one neighborhood or
>city at 110 to use up the 110 volt lamps, and another area at 125 to use up
>the 125 volt lamps. This practice declined with the advent of better lamps
>and was pretty much obsolete by World War One.
>
>
Check out the IEEE historical section. The added voltage was built
to compensate for voltage drop. Edison determined that the optimum
voltage for his carbon filament lamps was about 100 volts. However,
based on the physics of the Edison DC Central Station, the longest
practical run at that voltage would be just a few city blocks and the
drop averaged 10 volts or so at the maximum distance. Being DC,
there was no way to boost the voltage. Thus, 110 volts became optimum
at the generator/central station.
Beachcomber
As systems progressed, utility companys raised the voltage to 115,
120, and eventually a maximum of 125 volts as it became economically
more efficient to transmit at the higher voltage. By this time,
tungsten lamps had replaced the carbon filaments
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