ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades 120 V; 60 Hz vs. 240 V; 50 Hz

The US, Canada, part of Japan, Taiwan, Cetral America and a few other countries here and there use 110~120 V; 60 Hz as their standard single phase voltage. The 3 phase industrial voltage is 440~480 V. Canada also uses 550~600 V for industries

The rest of the world use 220~240 V; 50 Hz for single phase voltage and 380~415 V for industry.

What is the history of this difference? What is the advantage/disadvantage of one over the other?

What about sockets and plugs? What are the advantages/disadvantages of round pin vs. flatpin?

A few hits…
https://www.electrical-contractor.net/ubb/Forum1/HTML/002075.html
http://www.ieee.org/organizations/history_center/faqs.html
http://www.eng-tips.com type thread238-3663 in the search area




[This message has been edited by Bjarney (edited 08-03-2003).]

With travel as it is today, it would certainly be convenient if the whole world had adopted a single plug style and a single voltage/frequency standard. Unfortunately. we'd be back to the question of standardization we've been discussing in the cable thread and the problem of who would change.

Europe in general uses 220/380 (or 230/400V) power now, but in many countries they had 127/220V three-phase systems. I think our Belgian friend will confirm that there might be one or two places there which still have such a system, although with only 220V phase-to-phase loads these days.

Britain had 120/240V (or thereabouts) 3-wire DC systems in the very early days (e.g. late 19th century, earyl 20th), but most of these were upgraded to the 200/400 to 250/500V systems which survived in some older town areas until the early 1960s.

ECN Member C-H has a nice web site that shows the voltages and plug types for many countries.
http://electricity.does.it/

Not sure about consumer appliances in general, but the IEC320 C13/14 connectors {like on the other end of electronic-equipment power cords} and ~90-260V switchmode power supplies have been a significant advance in 'world power.'

230V 50hz as used in Europe has a few advantages.

1) Any modern outlet (13amps(UK)-16amps(Europe)) can easily and safely supply at least 3000W making it ideal for portable heating, electric kettles, esspresso machines, irons, high powered vacuum cleaners, washing machines, dryers etc etc.

Many EU countries go one step further and hook cooking and heating appliences up to 380V 3-phase.
Homes may also be supplied with 3-phase with different circuits taking 1 phase + neutral (220V) to balance the load.

2) Because of the higher voltage cabling doesn't need to be quite as heavy.

3) distribution networks are not quite as transformer laden as they are in the US. Local distribution in urban areas can be done at the 220/380V supply voltage distributing power to an entire block / street from a single large transformer (substation).

Rural distribution is, at least here, similar to the US though (i.e. dependent on lots of local pole top transformers)

The US system has the advantage of using lower voltage (110-120V) which is, arguably, slightly safer. With the option of using 240V for heavy appliences, like dryers, as it's a 3 wire system.

However, both 110 & 220V will do a very nice job of killing you. (Bare in mind that early electric chairs operated at 110V!!! albeit DC) It all depends on how much current passes through, where it goes en route and for how long.

Modern RCD (Residual Current Devices) and equivilants in the US have made the chances of surviving a shock from either system much better.

As for the 50 or 60 Hz question:

The US settled on 60 Hz.. Fits nicely into the system of seconds, mins, hours.. 1/60th of a second = 1 cycle.

The Europeans went for an almost metric frequency basically.

The current oscillates 100 times per second (completing a full cycle 50 times per second)

giving you a frequency of 50Hz.

Nice round number.

It amazes me that the entire European area managed to pick 50Hz.. Imagine if every country had gone for a different frequency!!

However, there is really no advantage to either 50 or 60Hz they're just 2 standard frequencies adopted as conventions.

Yes, Confirmed. It's even worse than that. I have heard of new building or even whole streets which still can only get from the PoCo 3x230V !

Belgian,
Presumably all houses wired this way use the TT earthing system?

On the 50 vs. 60Hz question, there is a minor advantage in that with 60Hz the transformers can be a little lighter for any given loading. 50Hz was used in some parts of America in the past. Bjarney posted a link some time ago to an article about the 1930s conversion of the Los Angeles area from 50 to 60Hz. Can you remember that link, Scott?

True, 110 and 220V can both be deadly, but the first electric chair used a lot more than 110V and most certainly wasn't DC.

I've seen values of around 1500 to 1700V quoted for the first use of the chair in 1890. Thomas Edison played a large part in getting the State of New York to adopt the chair, and he was firmly of the opinion that DC was far safer than AC (how much his belief was colored by rivalry with George Westinghouse is very much open to debate).

Some people have gone so far as to suggest that Edison's insistence on the use of AC for electrocution was an attempt to create a distrust of AC in the minds of the public ("Look, they're using AC to execute criminals, so it can't be safe to have in our home.")

The article is Crookshank, C., Kinsler, M., 1936 Los Angeles Synchronous Clock Project [History] IEEE Power Engineering Review, Jun 1997, Volume: 17, Issue: 6, ISSN: 0272-1724

I remember learning that originally all the electric power produced in the US was DC. Thomas Edison was actually a proponent of DC. It was said he did not know how to do the math for AC. It was a German immigrant who pioneered AC and the invention of the 3 phase AC motor helped cement the use of AC over DC.

The first use of AC in the US was at 25 Hz. I guess the generators in those days were not efficient enough to produce 50 Hz voltage. 50 Hz was not chosen because of metric, but because it was twice 25 Hz, and machines that ran at 25 Hz could be easily upgraded to run at 50 Hz.

It was an American clock maker who is responsible for the 60 Hz standard. He could sell his clocks more cheaply if he could synchonise them to the line frequency and if the line frequency was stable and of course if the line frequency was 60 Hz. He gave the presidents of various power compnaies gifts of clocks and in order for them to work or keep proper time, the power companies had to insure the frequency was right and stable. This is what established 60 Hz in the US.

What it all boils down to, was the US settled for convenience and the rest of the world for economy. Resources were in abundance in the US 100 years ago and so conserving was not an issue. Now, it may be, but the standards are established and it would cost a fortune to change them.

Those countries that the US played a major role in electrifying use the same power standards as the US. European colonies tend to follow European voltage standards. Korea is the only large scale industrial country I know of that switched from 120 V single phase to 240 V, using the schucko plug and German socket. But, they still use 60 Hz.

Not only 3x230V use TT system. ALL residential and small buisinesses use TT system in Belgian.

Question from the left side of the pond on ratings…is "3x230" 230V ø-ø or ø-n...for 3ø 4-wire?

And, one more time…a TT system is a solidly-grounded at the wye/neutral point of the serving {utility-owned} transformer, right?

The 3x230V nomenclature is a peculiar (from our perspective) way of specifying that the supply is 3-wire, no neutral provided, with 230V between phases. In other words, it's a 127/220 wye (or 133/230 I suppose, nowadays) system, grounded on the star point but without a neutral distributed to each house. Some parts of Europe did use 127/220 4-wire in the past with 127V appliances.

Yes, TT has a solidly grounded neutral at the supply transformer. But the grounding busbar (and thus the EGCs to the circuits) are grounded only to a local rod. They are not bonded to the neutral in any way, so the sole ground-fault current path is the earth.

John,
I think you're referring to Nikola Tesla, who did a lot of development work on AC machines. He often seems to be the "forgotten pioneer" in some electrical histories.

That covers it. Thanks for the details, Paul. I suppose such a setup is a good reason for ELCBs?

Yep -- The TT system results in a high loop impedance, which necessitates the use of an ELCB/RCCB/RCD (or whatever they're calling it this year!) for ground-fault protection.

JohnS:

The 25Hz systems in use in the US were never used in Europe though. So I don't see how European 50Hz had anything to do with the Niagra Falls system etc? So I doubt it was economy issue.

During the early days of Electricity in Europe the German company, AEG, was the European equivilant of Westinghouse or Edison. It came up with many of the very early DC tram systems. However, there is evidence of AEG 50Hz 3-phase systems very early on. They made a lot of sense for industrial drives etc. By 1920 220/380V 50hz was adopted in Ireland for example and it had been around for a good few years before that.

AEG and Siemens in paticular seem to have developed a huge proportion of the features of the commercial electrical systems used in Europe today.

25Hz was used during the installation of the 25kV AC railway systems in Britain.

I'm not certain, but I think they may have changed them to 50Hz now.

No, it was not Nikola Tesla i was thinking of, it was Karl Steinmetz.

See:
http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=Steinmetz&as_q=%22Alternating+Current%22
http://inventors.about.com/library/inventors/blsteinmetz.htm

I doubt any railway company in their right mind would use any AC frequency other than 50Hz in a 50Hz country unless they wanted to either generate all the power themselves and loose the ability to buy it commercially or else spend a fortune on electrical gear to change frequency!

Producing DC's not such a huge problem but with modern variable speed drives etc etc. it doesn't seem to offer any advantage.

Germany, Sweden and a couple of other countries use 16 2/3 Hz for trains.

I thought that was the case C-H but I couldn't chase the info down. DJK makes a good point though - where do they get their power.

I think in the UK (as common elsewhere in the rail industry) the traction current and signal systems (where both are ac) are on different frequencies to prevent interference. I thought I read somewhere that the UK uses 83.333' Hz(?) in these cases, presumably solid-state derived.

Interesting that 16.666' is 1/3 of 50Hz - no interference protection there from harmonics.

Before power electronics, I think the only choice for frequency conversion was motor-generator sets.

A previous employer had an 18,000HP motor-generator set that was 13.8kV 3ø in, and DC out. Excitation of the DC side could be varied rapidly, to ramp the output accordingly. It was a big DC power supply that could be controlled very tightly. It could only be started with clearance from the local electric utility.

I've done a little searching, and it seems that the 25kV system in the U.K. has always been 50Hz, fed from the National Grid.

What I must have had in the back of my mind is this old 6.6kV 25Hz system.

From the same website:

Hutch,
16 2/3 Hz was adjusted to 16.7 Hz to avoid this problem. I left that part out

[This message has been edited by C-H (edited 08-08-2003).]

Well Niagara Falls still has at least 1 turbine that puts 25hz for the big steel mills in Hamilton.

Motor - Generator sets must be very inefficient... what kind of energy loss would you be looking at?

djk,
Motor-Gen Sets have a HUGE loss ratio.
This is only recuped where something like a Ward-Leonard type system is used to regenerate some of the losses lost in the Generator, but I am told that a normal Gen-set only runs at 60-70% efficient.
This is probably why they never really caught on as a real option for a UPS system.

Trumpy—that is a very good point. Who's ever been in an equipment room with M-G sets that was "comfortable"—er, cool and quiet? I think though, that for many decades M-G sets were the most practical version of power conversion—until rugged SCRs came along.

[Mercury-arc rectifiers—like Ignitrons and Thyratrons—filled in between the two, but were a pain to keep running.]


[This message has been edited by Bjarney (edited 08-09-2003).]

Since Europe runs off the more common higher voltage system do they still require pole top transformers or is it done completely with the substations? Do you know where I can find some reference matterials about the pole top transformers that are in use in Europe.

I don't know about the rest of Europe but here in Ireland we use substations in urban areas.

Power would come in from the grid at transmission voltages of up to 400kV to a large substation near a town/city. It's stepped down to a medium distribution voltage of either 38kV, 20kV or 10 kV and from there goes out to local substations.

Typically every new housing development or each area of a city would have one. They often provide a number of 3-phase +N (380V) circuits which would be distributed either underground or overhead.

Small commercial users (small stores etc) and domestic users typically take 1 phase + N (220V, nominally 230V)

Other users take 3 phases 380V (nominally 400V) +N

In rural areas a 3-wire (3phase) distribution system operates at 10kV or 20kV.

Pole top transformers are used to step the voltage down and to either provide 220V (domestic) or 380V (to larger farms/guest houses/hotels/schools etc)

You won't find pole top transformers in towns or even relatively small villages though. They'll always have a small substation.

Even where 2/3 houses are clustered together a larger pole mounted transformer may be used and a small 220/380V overhead distribution system will hook up the houses.

As for types of transformers used. It would depend on the country in question. I know ESB, the main PoCo here uses a lot of ABB and AEG substations.

They also use ABB Pole mounted transformers: (Oil filled can type)


Here's the 3-phase version:


Here's a typical small pad-mounted substations that are used to service a block of houses or a new housing development. You'll find them scattered around the place. They're just large green street cabinates. Often located at the side of a park, down a lane etc..



All of the above are ABB

AEG and Siemens also supply similar set ups.

This is a bulkier looking Siemens transformer, something similar is seen in pole mounted applications here. Or as part offenced off substations.


The large substations that step-down from transmission voltages are pretty serious plant. Usually a large fenced off area with lots of transformers and switch gear.

for further information visit: www.siemens.com www.abb.com www.aeg.com www.alstom.fr
All of the above make transformers for the EU market.

I'm sure there are others too..



[This message has been edited by djk (edited 08-19-2003).]

Hi there studentlearner, and welcome to ECN.

I'll take your question as an opportunity to re-post some images of British apparatus to give you an idea.

Compared to the U.S., final distribution here tends to have a smaller number of larger transformers. Like Ireland, Britain also has sub-stations in towns and villages, with a 3-phase 4-wire distribution network at 240/415V. The majority of homes take just a 2-wire 240V feed from this system.

Here's what a typical small sub-station looks like from the outside:



And here's the apparatus within:


In rural areas, or the edge of town where a group of houses stand on their own, you might see a 3-phase pole transformer, like this one:



Single-phase transformers are normally found only in rural areas where just one or two houses need to be fed:




[This message has been edited by pauluk (edited 08-19-2003).]

I received the following by e-mail from a Mr. Jerry Hayward:

{Edited to correct name -- My apologies! }

[This message has been edited by pauluk (edited 09-13-2003).]

The one thing that always supprises me is how uniform European Electrical systems actually are.

All of Europe, with the historical exception of the UK, Cyprus, Malta and Gibraltar, used 220V 50 Hz

The UK settled on 240V also at 50Hz.

Making it easy to jump to 230V 50Hz as a harmonised nominal standard.

I just find it amazing that unlike in many other areas that we didn't end up with 5/6 different frequencies.

With the UK on 66.6666 Hz and France on 100 Hz or something along those lines


[This message has been edited by djk (edited 09-14-2003).]

DJK:

Are the European countries interconnected electrically?

I think the USA and Canada are. I don't know about the USA and Mexico (even though both have roughly the same nominal voltage and use 60 hertz as frequency).

Yeah, most EU countries are interconnected these days (in many cases have been for many years) and power is bought and sold all over the place between generators and distributers etc. (Within the European Union a fully deregulated power market is supposed to operate in theory anyway.. or at least that's the plan!)

Depending on which countries you're talking about the interconnectiors may be at 50Hz or DC. Generally EU countries have very similar frequency tollerances but I would suspect that for much of contenental Europe you're more than likely getting the same 50Hz.

However, perhaps unlike North America, the system would tend to consist of national grids which are interconnected at points rather than one pan European grid. I don't think you could get the cascade effect that happened in the North East of the US / South East of Canada.

Although are there state/regional grids in the US too?

Ireland's one of the few exceptions (being an island), ESB Networks only recently having opened a number of high tension interconnectors to Northern Ireland and until very recently Northern Ireland wasn't connected to the rest of the UK, however a major underwater DC interconnector is now in operation.

There is a proposal to run an interconnector from the Republic of Ireland to the UK, also very high voltage DC but as yet its cost far outweights any benefits it might bring as there is adequate capacity and a lot of new generating capacity from various companies coming online here.

Interconnectors from the UK to other EU countries are only relatively recent too. Again, being an island there are massive cost implications to large underwater interconnectors so the benefits have to be very clear before any company will invest in such a venture.

I know there has been a DC interconnector between England and France since at least the 1950s, possibly earlier. The one-hour time difference between us, along with French working/dining hours tending to be a little different to ours meant that our peak demand times don't coincide, so the mutual benefits were recognized quite early on.

I've tried to track down some information on the net as to when it went into service, the original power capacity, and so on, but haven't been able to find anything.

Yup. The UCTE has strict requirements for grids that wishes to be connected to the UCTE grid (which simply consists of the national grids of UCTE countries). If you don't have enough reserve power (long term), you'll be refused connection. I don't know what they do with countries that are already connected but starts to cheat.

Some countries are split between different grids: Half of Denmark is connected to Germany (UCTE), the other half to Sweden (Nordel). Ukraine is split between the grid of the former Soviet Union (CIS) and the UCTE grid.

[This message has been edited by C-H (edited 09-15-2003).]

Some minor followup US references...
djk, a couple of maps on the US system… http://www.nerc.com/regional/ http://www.wecc.biz/maps_diagrams/nerc_int.pdf

Sven, on your question about Mexico’s involvement in the North American system, officially it’s described as “…a portion of Baja California Norte, Mexico.” The 1997 NERC transmission map shows 230kV lines in far NW Mexico extending south ~25-50 miles to Cipres and Cerro Prieto (could be city or substation names.) There are probably some southern New Mexico and Texas towns that are electrically interconnected [<69kV] to a few border cities in Mexico, as are some local telephone exchanges.

Some more from Mr. Hayward:

Some interesting points there. I knew of the vast variety of systems in use in the London area around 1918, but I hadn't realized that parts of East Anglia (in which I have lived for six years!) didn't convert to 50Hz until so late.

Standardization of voltages to 240/415V took even longer in Britain, the process being completed only in the early 1970s.


[This message has been edited by pauluk (edited 09-15-2003).]

In my first apartment as an adult in NYC the power was 110V DC, powered from a generating plant around the corner! Had to get a noisy inverter to play my 78 rpm records. (For those who know New York, it was the lower east side, Ave. C and Stanton).

Edison's DC power plants were placed all over the city since it was not economical to transmit 110V DC at distances.

One frequency note: I have read that 25Hz is more efficient for large motors, and that parts of the European rail system uses it today. 60 Hz gets you beyond the noticeable flicker frequency for lighting.

Karl

Karl — See http://www.coned.com/sales/business/bus_elec.htm for utility-offered savings for 'upgrading' utility-furnished DC service in the NYC area. I don't know how long the program is supposed to last, but I'll bet there are some DC elevators in older apartment buildings in Con Ed service territory.

About 10 years ago, an associate in meter-testing equipment design told me he had been contacted by the Con Ed metering department to make an AC-powered test set for DC-energy meters, for their aged test instrumentation employed lead-acid storage batteries and large resistive-heater load banks for tests, and lugging those in an out of basements was “inconvenient,” to say the least.

[Note that (likely long-existing) 2-phase AC service is still listed as available in Con Ed and PECO systems. It's interesting to note that General Electric shows 2ø 5-wire as one of the available forms for one of their microprocessor-based energy meters—model "kV".]




[This message has been edited by Bjarney (edited 09-15-2003).]

Karl Riley said:

Yeah. I know that area. They call it "Alphabet City" You should see what's happened to it now!! It's going yuppie!!

WOW!! 110-volts DC?? What year was this? I thought DC was totally gone from residential applications in this town by the 40s or 50s.

Does anyone know when 110-volt DC for residential applications totally dissapear?

Of course you could get AC/DC radios well into the late 60s & early 1970s (transformer-less 5-tube "all American 5" sets). Reason was they were cheaper because manufacturer could avoid the cost of a transformer.

I heard that there were still a few buildings in New York that were on DC. But these were factory buildings.

I actually wonder if any houses in this country still use 110-volts DC for their appliances.

Wonder if those inverters are still available. I know you can get inverters to power 110-volt AC devices off a 12 volt DC line but that's different.

What types of plugs were used on the 110-volt DC system? Did they wire it with regular NEMA 1-15 and 5-15 sockets or did they use something more like this: ( -- | ) - with one horizontal and one vertical slot ?

That must have been weird if you plugged in your DC - powered fan and it started spinning backwards...

What about a DC powered blender or electric clock?

"Heyyyy...why is my clock running backwards!! "

*FLIP THE PLUG*

"Oh...much better!"

[This message has been edited by SvenNYC (edited 09-15-2003).]

Bjarney, I am amazed reading (on a webpage of all things) an encouragement to change from DC to AC in 2003!

Do I take it therefore that there are still some residential premises powered at 120V dc in NY,NY or is this just for utilities like lifts etc.? It does talk about lighting. Do they use the same NEMA receptacles? It reminds me of the high-pressure hydraulic mains for powering lifts in UK cities whose pipes are still extant - but now tend to contain fibre-optic cables!

Same webpage - steam powered air-conditioning (2003!). I know this is an electrical forum, and I vaguely understand gas refrigerators, but how on earth do these work?

[Sven, our posts crossed in the ether! ]

[This message has been edited by Hutch (edited 09-15-2003).]

European railways use a vast variety of systems. As far as I know Italy and France are mostly 1500V DC, I think there are 3000V systems, Austria, germany and some other countries have agreed on 15000V 16 2/3 (or more correctly now 16.7) Hz. Tram and subway systems are even worse, they run on 500V, 550V, 650V, 750V, 900V, 950V,... Vienna alone has 650V (not sure, maybe the Trams are 750, not 650), 750V catenary, 750V third rail, 950V (all DC) and 15kV 16 2/3 Hz AC. The Vienna Stadtbahn network that was opened as an urban steam railway system with interconnected lines and trains going as far as 100 or more km out of town is now split up into 3 isolated systems. 1 of the 3 lines uses 750V DC third rail (Vienna subway system), 1 is 750V catenary (tram style, but officially called subway), only the third line is still full railway system, 15kV AC, but the connections to the surrounding area have been chopped as well, even though they could reopen them any day.

In Britain, rural areas wich were electrified in the later years went straight to AC, but those districts which got electricity early on were wired with 3-wire DC systems.

These were gradually converted to AC over the years, but the central districts of some older towns still had DC mains into the early 1960s.

AC/DC radios and TVs of the time used a cheap half-wave rectifier with one side of the line connected directly to chassis. The tube filaments and dial lamps would be series-wired and connected straight across the incoming AC.

With the reversible 2-pin 5A plugs in common use for radios, plugging in the wrong way to a DC outlet would result in the dial and tube filaments glowing fine, but no B+ supply and thus no sound (or picture).

Where a 3-pin polarized plug was used, those living in homes fed from the negative "outer" would need to wire their radios so that the chassis would be live. With non-identified twin cord, it would be trial-and-error to get the connections the right way, or for color-coded cord they would need to connect the red to neutral and black to live (i.e. the opposite way to "normal").

The problem arose then of course, that the plug would need to be rewired for the set to work in a house wired on the other side of the supply!

Paul, would this domestic dc be 120V to ground or 240V to ground?

My NYC DC apartment was in 1950 - 52. The plugs were the same as AC. No ground, of course.
For nostalgia sake, the bath tub was in the kitchen, with a cover over it to use as the kitchen counter. There was no heat, but since I was on the 4th floor, enough heat came up from the apartments underneath to make it liveable. Rent, shared with a college buddy: $15/month.

Karl

For the US, it looks like the current iteration of the NEMA wiring device standard {WD6-1997} does not specify AC or DC for 1-15 plugs and receptacles [simply, 125 volts, 15 amperes, 2-pole, 2-wire.]



Note that is not the case with switches—almost all these days are marked AC only. For interrupting DC current—even a purely resistive load—it is a whole different ball game. I don’t know how that meshes with unplugging an appliance from a DC circuit. You would think that arcing could be much greater, for one because AC is momentarily zero every 8.3 milliseconds {each ½ an electrical cycle} allowing a degree of natural arc snuffing. DC does not have that luxury.




[This message has been edited by Bjarney (edited 09-16-2003).]

Speculatively, in NYC there are probably some old basement motor-generator sets that are owned and maintained by Con Ed for changing the utility’s local AC to DC, presumably upstream of a DC watthour meter. There might also be some “modern” transformer-silicon rectifier-reactor-capacitor converters. Voltage likely would be around 110/220V DC, consistent with the history of ‘Edison 3-wire’ service. Long Shot Guess is that there may some ancient elevator or ventilation motors, and maybe a trace of incandescent lighting in common areas.

The motors would be the universal AC/DC motors, so polarity wouldn't matter.

Well into the 1970s direct line powered radios were sold. Sometime in the 1960s they made them solid state (Have an RCA one somewhere). I won't say valve radios werent, because a record player my mother bought new in 1969 have 50EH5 amp valves.

DC was never really used here in Ireland, except at the very very early stages of electrification late 19th and early 20th century and then really only for lighting. (It was derived from the tram systems) ESB switched over to 10kV & 220/380V 50 Hz distribution very early on.

When did other countries in Europe switch over to 220V/380V 50Hz AC? And were there other systems in use in between? (I know the 127/220V system was, but when was that phased out? How did it work? How was it presented etc?)

We were pretty boring and had 220V + Bonded Neutral since the 1920s.


[This message has been edited by djk (edited 09-17-2003).]

Vienna: Some districts had 127/220V AC (probably) in 1903, others had 220/440V DC until 1965. As far as I know DC had the same round pin outlets as AC had later. From the 1950ies on (maybe earlier) the remaining areas were converted to 127/220V AC, others to 220/380V. The last 127/220V systems were converted in the late 1970ies. 127/220 meant the customer just got 2 phases of a wye system and no neutral. Large houses got all 3 phases. In Berlin 127/220 still exists but is supposed to be phased out this year. The customer didn't see much of a difference, except for having 2 phases when sticking a phase probe into a receptacle. Naturally polarization was completely useless with 2 equal phase conductors, so there wasn't any color coding.

Classicsat wrote:


Be careful, however. The "hot chassis" solid-state sets are not for plugging into DC supplies!!!

In fact, some of those radios had big labels in the back that said "Caution, Do NOT plug into DC"

Also, while the RADIO section of these transformerless sets could operate on DC, a lot of them came with clocks.

You guessed it. Those clocks could only run on +/- 120 volts AC, 60 cycle. The label on the back or bottom would say 120 volts AC only, 60 cycles (or 60 c/s).

I think General Electric kept making those solid-state hot-chassis sets well into the early 1980s. I have a bunch of radios like that here.

There is a big 3-inch cement-encased dropper resistor in the circuit that gets pretty hot to the touch, although not as hot as the droppers inside the 220-volt AC/DC radios used to get (those used to sometimes burn off the cardboard back covers on the radios!! ).

I HATE those radios with resistance flexes -- I will never buy one of them. No matter how cute they look.

[This message has been edited by SvenNYC (edited 09-17-2003).]

[This message has been edited by SvenNYC (edited 09-17-2003).]

Paul,

Where did the distribution systems get the DC? Local power plants with DC generators? It would seem a little difficult to get it from the 1960s national grid

I hope this is not beating a dead horse, but there is an interesting synthesis that was bound to occur somewhere in the world. On 220Y/127V, that seems to be a fairly standard voltage in Central America, but typically at 60Hz. Maybe C-H can confirm or dispute that supposition.

In a catalog listing for Jefferson Electric three-phase ventilated dry-type transformers…
‘General Purpose—Latin American Voltages' 460 V — 220Y/127 V http://www.jeffersonelectric.com/pdf/3-PhaseVent.pdf pg 5

220Y/127V 60Hz in Central American voltage is likely found where 3ø service is brought into larger buildings. This may be the case for some of the Caribbean Islands too. [It’s worth noting that for North America, 127V is also the upper end of permissible voltage for nominal 120V circuits.]

Note that the plain-vanilla North American version of this type of transformer is rated 480 — 208Y/120V {and occasionally 480 — 240/120V 4w &#8710;.)






[This message has been edited by Bjarney (edited 09-17-2003).]

djk — The need for very localized DC generation from rotating machinery would almost have had to have been the case, given voltage drop in relatively low-voltage DC distribution conductors. It seems about ½ mile was the most optimistic extreme for DC circuit lengths without distribution conductors getting ridiculously huge.

The prime advantage of AC transmission and distribution is making use of the AC transformer, to raise [and then lower near the load] voltage, having sent it at a much higher voltage {with much lower losses.}

The one other major advantage of AC is its ready use for brushless induction motors—the ‘current chopping’ needed for DC motors through brushes, commutator and armature generally became no longer necessary with AC.

It is said that early on, Nikola Tesla was hired by Thomas Edison to fix excessive commutator sparking problems in early DC generators and motors.




[This message has been edited by Bjarney (edited 09-17-2003).]

At the times I'm talking about, the British 3-wire DC systems were 240 to ground, and thus 480V between outers. (Or thereabouts: As this was before standardization, the specified nominal voltages were between 200/400 and 250/500V depending upon the district.)

Normal residential services were 2-wire 240V, with half the houses tapped from the positive pole and half from the negative. Commercial premises could get a 3-wire 240/480 service.

I understand that there were some 120/240 3-w systems in the very early days (e.g. late 19th/very early 20th century).

Yes, a BJ has mentioned, DC is not easily transposed to higher voltages and the low-ish voltages severely restricts transmission range. Thus DC systems were only practical in urban areas with loads close to the generating station.

I know that parts of France had 127/220V in the past, and this is a question I posed on a French forum some time ago.

A couple of people told me that there was a gradual change from 127/220 to 220/380 after World War II and into the 1950s. But apparenly some areas still had their 127/220 services in the 1960s and even 1970s -- These with actual 127V outlets, not the neutral-less two-phases to give 220V as still exists in some parts of the Continent.

In Britain at least, the transformer-less design survived longest in television sets. Live chassis sets with half-wave rectification were still common in the 1970s, which isn't surprising considering that TVs were also one of the last mainstays of vacuum tubes.

By the early 1980s, TV design started moving toward switched-mode (chopper) power supplies. Many of these designs resulted in a chaasis which floated in potential to about half the mains supply level, no matter which way the supply was connected.

So with the earlier sets, one could at least guarantee a zero-volts chassis by observing correct polarization, but on the new sets the chassis would sit at 120V no matter what.

Isolation transformers at the ready!

I have worked on both 480V and 600V in industry in Canada.
600V is lower cost in the long run, but it scares the heck out of me. Just kidding.

480V is 277V to ground, 600V is 347V to ground. We electricians get most of our shocks to ground.

347 is the most dangerous voltage to work with. Anything higher, and it 'throws' you out of the circuit, anything lower you still have muscle control to 'pull' away.
I am told 347 just keeps you in the circuit until either you or the grid say 'uncle'. Guess who usually wins.

You can bet I wouldn't want to argue with 347 volts!

Looking back at the transformers:
I can see that the 220Y/127 arrangement must be the European influence on many Latin American countries, but I wonder how 460V came to be a standard there?

Keep in mind that the voltage seen across your normal two-pin plus ground household or office socket in Colombia, Ecuador, Panama and Venezuela is 120 volts at 60 hertz -- Live to Neutral.

I believe it's a 120v Line-Neutral/240v Line-Line system...in Colombia at least.

There was a small area in Bogota (the capital city) that used to have 150 volts. Supposedly it was the old historic center (Candelaria district). I don't know what happened...they must have converted that neighborhood eventually.

I've never seen 150 volt appliances or lightbulbs for sale there. Everything is marked either 120 or 125 volts.

However a few Colombian-manufactured household wiring devices (some plugs and small 120-volt outlets) meant for 120 volts were rated to 150 volts. Probably because of that legacy 150 volt system. However, the newer versions of these are being re-stamped 125 volts now.

[This message has been edited by SvenNYC (edited 09-24-2003).]

What outlets were used for 127V + Neutral in France and elsewhere?

I believe that 150V was also the standard in at least one Asian country at one time.

I think France used the same type of outlets on 127V as are currently used for 220. I've seen references which suggest that NEMA 1-15 style was used in the past (that's the two-hole ungrounded version) in both France and Germany, but I've never been able to confirm that.

This was an interesting discussion we had about the different systems, so I thought it worth bumping up the list for the benefit of ECN's newest recruits.

The only case where this is definitely true are isolation trnasformer shaver sockets, most of which would indeed accept both round 4mm pins and NEMA 1-15. I've also seen a few Italian made dou sockets of that type but standard ones w/o transformer. As far as an elderly radio guy told me Austria always had round pin ungreounded sockets for 110V AC and 220V DC and AC, but I'm not sure whether there ever was something like 110V single phase, more likely it was 127V delta.

I wonder if housing for American soldiers serving in Germany and other places might have had Nema sockets. As the world changes, houses originally built for foreign soldiers are now owned by locals.

That's a possibility. I know that AFN TV in Germany was to NTSC standards, so it seems quite probable that they imported all equipment and wired to U.S. standards on site.

I posted the question at a German/Austrian/Swiss board and now I'm waiting for replies. There are some really brilliant guys there.

I've heard that at embassies etc they often have 2 systems. That doesn't only apply to US Embassies either.

Ok, got a real nice reply. C-H, you were absolutely right! After WWII the US Army built lots of houses for the accomodation of the soldiers, and those had either 120V only or 120 and 220V side by side, the 110V stuff usually wired with US stuff, even using standard nail-on boxes in solid plastered brick walls. The guy noted that those boxes were really small and cramped. Whatever.
There are also NEMA 5-15 inserts for standard German modular series, fitting German boxes. He said he has some of these he doesn't need any more, if he doesn't want too much money I'll get them.

BTW, it wasn't only 1-15, 5-15 was and is used too. Even today the Army has everything wired to US standards.
And there were/are several NTSC TV stations.
Here in Austria the US left in 1955, and prior to this they didn't do too much construction, but in Germany they never left.

I was stationed at Bitburg Air Base in Germany during my stint in the Air Force. It was the trip to Europe I would otherwise never afford on my own.

We stayed in dorms that were wired with 220V schuko outlets, no 120 as far as I know. I had a step down transformer to run my dedicated 115V electronics, but most of it had a dual voltage switch.

No mishaps with 220 except the one time I didn't know what an immersion cup warmer was.

I plugged it in and went to fill the cup...came back and the coil had burned wide open.

I have a friend, now retired, who was also stationed in Germany about 40 years ago.

He tells of the tin army mugs they used and how they used to fabricate a makeshift clamp to hold an electrode centrally. They then used a clip lead to ground the mug to a nearby pipe or radiator and shoved the wire from the center electrode into the hot side of a convenient outlet.

Apparently they used a similar technique to cook steak between two metal oven grills!