Higher or lower frequency AC

There are two basic ways of converting electrical power from one frequency to another -

1) Electro-mechanical, using a motor running at one frequency linked to a generator running at the other 2) Electronic, typically converting the energy to dc and then converting the dc to the new frequency.

You possibly already have something that will convert 60Hz (or 50 Hz) input power to output power at any frequency from 10 -1000 Hz. It's called an audio amplifier. You just need to provide a low power signal generator of the required frequency as its input, plus, perhaps, a transformer at the output to produce "mains" voltage. A suitable amplifier will produce several hundred watts of output power at the desired frequency.

As to why the difference in frequency. Personally, I put it down to the arguments that a different frequency should be adopted outweighed those that the same frequency should be used. eg If you want to establish a new industry in a country and don't want to be swamped by imports from an established industry elsewhere - you adopt a different and incompatable standard..

This question comes up in this thread periodically.

In brief, electrical systems evolved into the standards we used today during the early years of the 20th century. Going back to the late

19th century, there was the DC central station, and limited power distribuiton to a few city blocks at low (110 V) voltatages (in the USA). Then came the AC systems of Tesla and Westinghouse, which allowed for long distance power transmission and interconnection of large generators at distant points.

In the early years of the US Electrical Industry, there were many different frequencies available 16 Hz, 20 Hz 25 Hz, even 40 Hz in addition to 50 and 60 Hz systems. In general, the lower frequencies were better for operating large electric motors (elevators, hoists, streetcars, and railroad locomotives) due to the lower inductive reactance.

Incandescent lighting became popular on these same systems, but at the low frequencies (50 Hz and below), there was a noticable flicker in the low wattage lamps.

Gradual interconnection and the development of network grids all but eliminated the oddball frequencies and 60 Hz was chosen to be the default frequency in the North American System along with a voltage of

110V and later, the split-phase 110V/220V system that is still used today. The voltage and frequency chosen was a compromise to take the best characteristics of the systems at the time and make them a regional standard.

Electric System Development in Europe was dominated by the Siemens AG who made many of the generators and whose engineers picked 50 Hz as the standard for Europe, with most distribution at 220V, and 3 phase as a standard.

No one at the time envisoned universal appliances, hair dryers, washing machines, computers, tv's, entertainment electronics, etc that could be used in any country. It was not a problem for many years until travellers started pluging their110V. electric shavers or hair dryers into 220V outlets and blowing them up.

Now we have universal power supplies and UPS sytems that put out either 50 or 60 Hz power at various voltages.

| Gradual interconnection and the development of network grids all but | eliminated the oddball frequencies and 60 Hz was chosen to be the | default frequency in the North American System along with a voltage of | 110V and later, the split-phase 110V/220V system that is still used | today. The voltage and frequency chosen was a compromise to take the | best characteristics of the systems at the time and make them a | regional standard.

It was split "phase" 110/220 as early as Edison's DC service in New York (though one would call it split polarity to be more correct).

| Electric System Development in Europe was dominated by the Siemens AG | who made many of the generators and whose engineers picked 50 Hz as | the standard for Europe, with most distribution at 220V, and 3 phase | as a standard.

As I understand it, they chose 50 instead of 60 because it fit better with the metric system. But I have no idea if this is true.

| No one at the time envisoned universal appliances, hair dryers, | washing machines, computers, tv's, entertainment electronics, etc that | could be used in any country. It was not a problem for many years | until travellers started pluging their110V. electric shavers or hair | dryers into 220V outlets and blowing them up.

Or plugging their 220V shavers into 110V outlets and watching them overheat and burn up.

| Now we have universal power supplies and UPS sytems that put out | either 50 or 60 Hz power at various voltages.

I'm still looking for a decent UPS that can do 240V 60Hz using the split phase wiring of North America. And surge protectors for it would be nice to have, too.

I thought it was because it made synchronous machines run at 3000 rpm, which is a nice round number.

On 13 May 2007 01:56:10 -0700 contrex wrote: | On 13 May, 05:42, snipped-for-privacy@ipal.net wrote: | |> As I understand it, they chose 50 instead of 60 because it fit better |> with the metric system. But I have no idea if this is true. |>

| | I thought it was because it made synchronous machines run at 3000 rpm, | which is a nice round number.

For that they should have either changed the clocks to have 50 or 100 minutes per hour, perhaps with 10 or 20 hours per day, or just used a frequency of 16.666667 Hz to get a nice round 1000 rpm (oh wait ... they actually did that for a while). OK, how about a nice round 50 rps?

They still do for traction on Scandinavian, German, Austrian and Swiss railways. It used to be 16 2/3 Hz (ie 16.6666 recurring) in all those countries but some have changed to 16.67 for technical reasons.