Curiosity for the day.... How/why did we settle on 60hz and not say 400hz?

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fastline

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As I am doing a repair on a switch mode power supply, I am wondering why in the world we run the USA at 60hz? Yes, random question! For those not familiar with an SMPS, these are DC power supplies used in nearly everything today. They exploit the advantages of running a transformer at very high frequency, making the transformer requirement tiny and cheap.

I realize really high frequency mains would be problematic for noise, but even running at 100hz would be a big change in transformer sizing. Surely there is a down side I am not realizing? Airplanes certainly have taken full advantage of higher frequency goodies.
 
Google skin effect. Big problem as conductors get bigger and frequencies go up.

DC has no skin effect to speak of.

I design load banks that operate up to 900 Hertz. 1/0 is about the biggest practical conductor size at that frequency.
 
fastline said:
why in the world we run the USA at 60hz?
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60hz is also very bad for causing heat fibrillation. It really is one of the worst frequencies they could have picked. If I had to guess, it's because of the base 60 we use to measure minutes and seconds. They had to choose something and didn't realize the unintended consequences of their choice, but after something is established, it's hard to change.
 
220803-0845 EDT

DC, 60 Hz and above are good for minimizing flicker effect.

DC is good for long transmission lines and lower losses, not good for arc quenching. Also good for interconnecting different systems.

60 Hz provides reasonably good results for 100 mile ranges. 400 Hz not so good for long distance.

Core material losses go up with increased frequency.

.
 
gar said:
220803-0845 EDT

DC, 60 Hz and above are good for minimizing flicker effect.

DC is good for long transmission lines and lower losses, not good for arc quenching. Also good for interconnecting different systems.

60 Hz provides reasonably good results for 100 mile ranges. 400 Hz not so good for long distance.

Core material losses go up with increased frequency.

.
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DC really became practical for system interconnection when the technology became available to invert high voltage to AC so that it could be transformed instead of requiring use of a motor-generator set.
 
I thought I once read something about strobe effect of incandescent lighting if frequency was too low being part of factor in choosing 60 Hz?

I know even 60 Hz is somewhat a problem with electric discharge lighting as the arc in those systems is extinguished 60 times a second, where the incandescent is driven by a heated filament and the cooling of that filament every cycle isn't enough to notice any change in light output without advanced instruments to measure with.
 
When AC came into fruition, lots of different frequencies were tried and rejected for various reasons. Tesla’s initial AC installation at Niagara was 25Hz, and that was still being used in New Orleans for the flood pumps up until Katrina. The first commercial 3 phase system was a GE 40Hz generator running some pumps in So. Cal., some early electric rail systems in Europe were 133Hz. 60Hz being chosen had nothing to do with the clock. It was that lighting was the big promise for expanding the reach of electric power and Edison’s light bulb had a noticeable flicker at any thing below 50Hz, then line losses started to add up above 60Hz. So between 50Hz snd 60Hz, 60Hz meant slightly smaller transformers, so we (North America) went with 60Hz while Europe went with 50Hz.

There is speculation that part of that decision though was that Edison, as owner of GE, was also heavily invested in what would become AEG in Germany. He knew that Siemens had an already existing and robust infrastructure for making generators because they dominated in DC at the time (Edison’s first DC dynamos used to demonstrate his lighting in New York were actually made by Siemens). Edison feared that Siemens would quickly adapt that infrastructure to dominate in AC generator and motor production too. So while Siemens was still pushing DC (as ironically, he had for so long), he used his influence at AEG to install 50Hz systems for Europe so that the equipment wouldn’t be compatible to export to America. That apparently worked.
 
fastline said:
As I am doing a repair on a switch mode power supply, I am wondering why in the world we run the USA at 60hz? Yes, random question! For those not familiar with an SMPS, these are DC power supplies used in nearly everything today. They exploit the advantages of running a transformer at very high frequency, making the transformer requirement tiny and cheap.

I realize really high frequency mains would be problematic for noise, but even running at 100hz would be a big change in transformer sizing. Surely there is a down side I am not realizing? Airplanes certainly have taken full advantage of higher frequency goodies.
Click to expand...
Actually a lot of the world is 50Hz. Countries in Europe, Africa, India, Australia and so on.
 
I realize much of the world is 50hz, thus why I mention the USA. When I mentioned 400hz, I was just throwing an example. I just can't help but think 60hz is an outdated frequency and probably many ways to optimize.

As for DC, don't even get me started because most non-electrical minds don't realize many appliances and devices actually run on DC in the home. Every circuit could be radically simplified in some cases. Things like AC compressors are FINALLY running proper inverter technology which allows soft easy starts, motor monitoring, variable speed control, etc. First thing you gotta do is make DC!

Obviously if you have DC though, none of these transformers are going to work! I have also seen what it takes to quench a high voltage DC arc.

Anyway, the skin effect is something I forgot about, and it is actually exploited in induction heating.
 
fastline said:
I realize much of the world is 50hz, thus why I mention the USA. When I mentioned 400hz, I was just throwing an example. I just can't help but think 60hz is an outdated frequency and probably many ways to optimize.

As for DC, don't even get me started because most non-electrical minds don't realize many appliances and devices actually run on DC in the home. Every circuit could be radically simplified in some cases. Things like AC compressors are FINALLY running proper inverter technology which allows soft easy starts, motor monitoring, variable speed control, etc. First thing you gotta do is make DC!

Obviously if you have DC though, none of these transformers are going to work! I have also seen what it takes to quench a high voltage DC arc.

Anyway, the skin effect is something I forgot about, and it is actually exploited in induction heating.
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I am right old codger- now in my seventies. A lot of my experience was variable speed DC drives so it is not exactly new technology. One of the paper mills was actually thyratrons. Believe it or not I still have one in my desk drawer. Life moves on.

 
Jraef said:
When AC came into fruition, lots of different frequencies were tried and rejected for various reasons. Tesla’s initial AC installation at Niagara was 25Hz, and that was still being used in New Orleans for the flood pumps up until Katrina.
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I believe the North eastern power grid still has 25 hz generators for the existing 25hz rail network as a plan to convert it all to 60hz was scrapped in the late 90's. You need to be a primary customer to get 25 hz where it is available, I am not sure if any still exist other than the rail.

Jraef said:
The first commercial 3 phase system was a GE 40Hz generator running some pumps in So. Cal., some early electric rail systems in Europe were 133Hz. 60Hz being chosen had nothing to do with the clock. It was that lighting was the big promise for expanding the reach of electric power and Edison’s light bulb had a noticeable flicker at any thing below 50Hz, then line losses started to add up above 60Hz. So between 50Hz snd 60Hz, 60Hz meant slightly smaller transformers, so we (North America) went with 60Hz while Europe went with 50Hz.

There is speculation that part of that decision though was that Edison, as owner of GE, was also heavily invested in what would become AEG in Germany. He knew that Siemens had an already existing and robust infrastructure for making generators because they dominated in DC at the time (Edison’s first DC dynamos used to demonstrate his lighting in New York were actually made by Siemens). Edison feared that Siemens would quickly adapt that infrastructure to dominate in AC generator and motor production too. So while Siemens was still pushing DC (as ironically, he had for so long), he used his influence at AEG to install 50Hz systems for Europe so that the equipment wouldn’t be compatible to export to America. That apparently worked.
Click to expand...
Very interesting indeed
 
fastline said:
I realize much of the world is 50hz, thus why I mention the USA. When I mentioned 400hz, I was just throwing an example. I just can't help but think 60hz is an outdated frequency and probably many ways to optimize.
Click to expand...
If what Jraef mentioned in post 8 is true it makes sense - Edison apparently wanted to try to assure that imported equipment wouldn't work so well in the US because it was designed to run on 50 Hz. This mostly effects motorized appliances - heating and lighting, particularly incandescent lighting, work fine on either frequency. You can easily transform voltages if they don't match up but changing frequency is a little different game, though with solid state components these days even that isn't as big of a deal as it once was.
 
Well at least we standardized. It would have been weird if southern California or who knows all of California stayed 50 hz. I always feel bad for Japan one country two frequencies and a odd duck of a voltage @ 100/200V.
 
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