240/120v? why

[LEO2854]

When I was studying Electrical Engineering, I was told that the US uses 120 volts because it was first to electrify. We had the first electrical systems in the 1870's/1880's and had the first large-scale electrification starting in the early 1890's, back when light bulbs had only carbon filaments. Apparently, carbon filaments worked best near 100 volts, but utilities picked slightly higher supply voltages like 110 and 120 to compensate for voltage drop. They reduced copper costs by using the hot-neutral-hot split-phase scheme we still use in residential, but most appliances were invented after lighting and so were designed to plug into lighting sockets that people already had installed, and thus to use lighting voltage and not to use the full voltage.

Europe however got started on large-scale electrification later, starting in the early 1900's. Europe (mostly Germany - Siemens et al) got started by using our electrical utility equipment and standards, but by then light bulbs used metal filaments and 220-240 volt bulbs were available. Using those, they could save more copper by running only two wires instead of three, ignoring the center tap and grounding one of the other wires instead. Appliances were built accordingly. The US, meanwhile, was already standardized on lower voltages. Other countries tended to adopt either the standard of their colonial overlord who forced it on them or the standard of their neighbors so that they could share power.

I don't know how true this is, but it has always made sense to me.

Good history lesson thanks

 

[dereckbc]

Was there much experimentation with this or did Edison or somebody just come up with it and it stuck?

When it comes to Edison, he failed miserable in the electric generation and distribution system. Edison was a low voltage DC guy, and thought high voltage and AC was too dangerous and expensive. It was Nicoli Tesla who who is the Father and inventor of the modern electrical generation and distribution.

Ok now to answer your question about 240/120. The reason is historic due to the DC system Edison used in NYC He choose 110 volts because because that is what his light bulb worked on.

 

[Besoeker]

And the perception here may be that those across the ocean can't handle more than one voltage. :grin:


Having grown up with it I do not find it complicated I find it good to have choices.

If everything operates from the same voltage you don't need choices. [/quote]
Simple.
:grin:

If I have a to move a lot of power I can use 480,

And we can use 400V if we want 3-phase power which is, of course, the same supply as the single phase 230V phase to neutral is derived from.
Simple and elegant.

if I need less power I can bring it to the end user at just 120 volt to ground instead of 230 to ground which IMO is no doubt safer.

From discussions here it would seem that the 120-0-120 is prone to losing the neutral with the resulting risk of an appliance being subjected to serious overvoltage.
That simply isn't an issue here.

 

[mivey]

If everything operates from the same voltage you don't need choices.
Simple.
:grin:


And we can use 400V if we want 3-phase power which is, of course, the same supply as the single phase 230V phase to neutral is derived from.
Simple and elegant.
From discussions here it would seem that the 120-0-120 is prone to losing the neutral with the resulting risk of an appliance being subjected to serious overvoltage.
That simply isn't an issue here.

Gosh, we are such miserable wretches. I wish we had elegant electricity. :grin:

 

[hardworkingstiff]

Gosh, we are such miserable wretches. I wish we had elegant electricity. :grin:

I tend to think the European voltage is a better choice.

Now, what about the 50HZ vs 60HZ? What's the story on that? Anyone?

 

[dbuckley]

The neat thing about a unified set of voltage is that you can have a unified set of connectors.

Once you get above the petty squabling which relates to what the household receptical is, you get to the standard induistrial connectors, the Ceeform's or C17 connectors, to IEC 60309. These are available in several voltage ratings, and currents (16, 32, 62, 125) and pin layouts (2,3,4,5,6,7), and weather resistance(IP44, IP67). They are cheap, hard to destroy, and easy to use.

A brilliant range of connectors.

 

[iwire]

And many of us used to NEMA stuff think that most of that foreign stuff like IEC items are cheap junk to be avoided at all costs.

For the most part whatever systems each of us 'grew up with' will be best to us.

 

[Besoeker]

And many of us used to NEMA stuff think that most of that foreign stuff like IEC items are cheap junk to be avoided at all costs.

Yes. Insular.

 

[Besoeker]

I tend to think the European voltage is a better choice.

Now, what about the 50HZ vs 60HZ? What's the story on that? Anyone?

Well, 50Hz gives you nicer numbers.
A half cycle is 10 ms for example, not 8.33333333333333333333......etc.

 

[K2500]

These are available in several voltage ratings, and currents (16, 32, 62, 125)...

I really expected your ocpd ratings to be in multiples of ten,you know, more metrified.
Though I suppose they may have been brought into use under your imperial system.

 

[robbietan]

When I was studying Electrical Engineering, I was told that the US uses 120 volts because it was first to electrify. We had the first electrical systems in the 1870's/1880's and had the first large-scale electrification starting in the early 1890's, back when light bulbs had only carbon filaments. Apparently, carbon filaments worked best near 100 volts, but utilities picked slightly higher supply voltages like 110 and 120 to compensate for voltage drop. They reduced copper costs by using the hot-neutral-hot split-phase scheme we still use in residential, but most appliances were invented after lighting and so were designed to plug into lighting sockets that people already had installed, and thus to use lighting voltage and not to use the full voltage.

Europe however got started on large-scale electrification later, starting in the early 1900's. Europe (mostly Germany - Siemens et al) got started by using our electrical utility equipment and standards, but by then light bulbs used metal filaments and 220-240 volt bulbs were available. Using those, they could save more copper by running only two wires instead of three, ignoring the center tap and grounding one of the other wires instead. Appliances were built accordingly. The US, meanwhile, was already standardized on lower voltages. Other countries tended to adopt either the standard of their colonial overlord who forced it on them or the standard of their neighbors so that they could share power.

I don't know how true this is, but it has always made sense to me.

thanks, that was very interesting.
in the Philippines, we used the 60Hz of the Americans and the 230 volts of the Europeans.
so we won't show favoritism for either

 

[robbietan]

I tend to think the European voltage is a better choice.

Now, what about the 50HZ vs 60HZ? What's the story on that? Anyone?

I thought that poles on a circular frame are easier to install for 60Hz than on 50Hz machines

I am absolutely sure though. should be interesting to learn

 

[hardworkingstiff]

thanks, that was very interesting.
in the Philippines, we used the 60Hz of the Americans and the 230 volts of the Europeans.
so we won't show favoritism for either

So nothing works (purchased from Americans or Europeans) as designed?

 

[LEO2854]

When it comes to Edison, he failed miserable in the electric generation and distribution system. Edison was a low voltage DC guy, and thought high voltage and AC was too dangerous and expensive. It was Nicoli Tesla who who is the Father and inventor of the modern electrical generation and distribution.

Ok now to answer your question about 240/120. The reason is historic due to the DC system Edison used in NYC He choose 110 volts because because that is what his light bulb worked on.

THANKS that is good info.

 

[RichB]

I keep seeing referance to Edison in here and his dist system--If memory serves--wasn't Edison pushing a DC system--no neutrals and no centertaps as mentioned in here--and Tesla/Westinghouse the AC system??

 

[gar]

100908-1344 EST

Using --- edison 3 wire dc distribution system --- as a Google search string results in some of the following:

From http://www.ieeeghn.org/wiki/index.p...ion_of_Buffalo:_Advent_of_Alternating_Current

In September 1882, the Pearl Street Station of the Edison Electric Illuminating Company in New York City went into operation serving 85 customers with some 400 incandescent lamps [Fig. 2.1]. This central station system, which was designed to serve an area approximately one-mile square, consisted of constant voltage direct current generators connected in parallel serving radial circuits with lamps connected in parallel.i 110 volts was selected on the basis of economics with copper being the systems largest cost [Fig. 2.2].ii It is remarkable that in the last century the voltage has been adjusted upward only slightly to today?s standard of 120 volts.

The next important development came less than one year later in July 1883 when a three-wire system went into operation in Sunbury, Pennsylvania with a 62 1/2 percent saving in copper compared to the New York system [Fig. 2.3].iii To serve the same load with two generators connected in series, the current is cut in half. The neutral current is zero with equal loads on both generators.

From http://en.wikibooks.org/wiki/Transwiki:Thomas_Edison

Electric power distribution
Edison patented an electric distribution system in 1880, which was essential to capitalize on the invention of the electric lamp. On December 17, 1880, Edison founded the Edison Electric Illuminating Company. The company established the first investor-owned electric utility in 1882 on Pearl Street Station, New York City. It was on September 4, 1882, that Edison switched on his Pearl Street generating station's electrical power distribution system, which provided 110 volts direct current (DC) to 59 customers in lower Manhattan.

From http://www.stealthskater.com/Documents/Tesla_06.pdf

The voltage level was chosen for convenience in lamp manufacture. High-resistance carbon filament lamps could be constructed to withstand 100 volts and to provide lighting performance economically competitive with gas lighting. At the time, it was felt that 100 volts was not likely to present a severe hazard of electrocution.
To save on the cost of copper conductors, a 3-wire distribution system was used. The 3 wires were at +110 volts, 0 volts, and −110 volts relative potential. 100-volt lamps could be operated between either the +110 or −110 volt legs of the system and the 0-volt "neutral" conductor, which only carried the unbalanced current between the + and − sources. The resulting 3-wire system used less copper wire for a given quantity of electric power transmitted while still maintaining (relatively) low voltages.

.

 

[Besoeker]

I really expected your ocpd ratings to be in multiples of ten,you know, more metrified.

Multiples of ten is a decimal system and not specifically metric. The use of this system for most metric (or SI) units does make calculations generally simpler than the Imperial system of pounds, feet etc.
The current ratings of circuit breakers and other load carrying devices as a general rule follow a pattern of increasing by a common multiplier.
For example, circuit breaker common ratings are 4, 6, 10, 16, 25, 40, 63, and 100 Amp. Multiply each by about 1.6 and you get the next. There are intermediate values also, 32A for example.
This kind of exponential series is commonly used in electronic components like resistors for example where each value in a series is roughly a a constant factor times the previous.

 

[SAC]

One thing to consider is the legacy of the DC voltage chosen (~110v), vs the later large abandonment of DC in favor of AC. With DC the distribution voltage needed to be close to the utilization voltage because there wasn't an economical way to step up the voltage for distribution, and then down for utilization. AC changed that and allowed higher distribution voltages, while still allowing compatibility with existing 100v luminaries, which didn't really care if the supply was DC or AC. With higher AC voltages available, larger loads (e.g., factory motors) could be more economically supplied, giving rise to other, higher, voltages available for utilization. However, compatibility with existing luminaries could still be achieved with relatively economical step-down transformers, not to mention that the lower voltage was adequate for typical household type appliances that started to appear at the time. Edison also made a big deal about the relative safety of lower DC voltage vs. higher AC voltage (including public electrocution of animals using "high" AC voltages), and perhaps this had an effect on the perception of safety with the early consumer. So the current system results from compatibility with legacy components, the switch from DC to AC, demands of economy, and public perception. I'm not familiar with the history of electrification of other countries, so I can't really comment on how things evolved differently there. However, this is on large part my speculation, and I don't have a good source to reference. So take my comments with that in mind.

 

[broadgage]

As others post, the reasons for different voltages in different countries are largely historical.

Early electric lamps were only suitable for very low voltages, often 32 volts, 50 volts or 60 volts.
Therefore early distribution was at twice the lamp voltage by a 3 wire DC system.
Technology soon improved and made 110 volt lamps viable, with distribution at 115/230 DC. This was used in the past in the UK, but when 240 volt lamps became available the voltage was doubled to 240/480 DC this remained the standard until the end of DC.
The USA stuck with 3 wire distribution at 115/230 or 120/240, the change from AC to DC retained the same voltage.
There was little demand in the USA for a change to a higher voltage, since 277/480 was available for larger loads and larger buildings.
The drawback of the USA system is greater complexity and the fact that three similar voltages are in general use (208,240,277) This requires 3 versions of everything, or appliances that tolerate a wide voltage range.
In the UK we changed from 3 wire DC at 240/480 volts, to 3 phase 4 wire AC at 240/415 since this was a good compromise between a relatively low voltage for lighting and a relatively high voltage for high power loads.

In mainland Europe some utilities used 3 phase, 4 wire AC at 127/220 volts, with lamps of 125 volts and appliances of 220 volts.
Such schemes were normally changed to 220/380.
A few parts of the UK used 127/220 but it was never widespread.
Likewise a few old UK systems used 120/208, but it was never widespread.

 

[RichB]

Huh--never to old to learn--thanks gar and all---I never really "looked" into it but now that you all point it out--one of those epiphany things--"oh Yeah---DUH"--Thanks guys!