why is it that in some countries the frequency of the line voltage available in homes is 60Hz and in some countries it is 50Hz. is there a reasoning behind this. i mean is one of them better than the other. if there is not much of a difference then why do countries have different frequencies. i always thought that 60Hz was chosen because it serves a better time base for clocks that are powered from the AC socket. isnt that true??? whats the story behind all this

 

60hz good for clock syncing, 50hz is good for maths


I think it was the US that started an AC grid and they chose 60Hz, there was no reason that they couldn't have picked 50Hz.

UK came next and wanting to boost their industry went for 50hz that way they wouldnt have to by from the US

50hz is very good to work with from a thd point of view. I know i will see some 5th and 7th for a 6 pulse and that is 250Hz and 350hz, slightly harder for 60hz

 

All areas of the US were not always 60 Hz and I suspect the rest of the world's electrical distribution has a similar history. Many industrial cities used 25 Hz power for a number of years and it might still be possible to find motors and other equipment operating at 25 Hz. I know as late as the 1980s that they looked at renovating an old hydro plant (very small) in the town where I grew up because the generating equipment was 25 Hz. The plan was to send the power into the city of Buffalo, NY where some customers still used 25 Hz power. Many of the factories in the Buffalo area had equipment installed and operating from early 1900s and the cost to change over was still higher than keeping the old system.

I have no idea why 25 Hz but it may have had something to do with rotating speeds, number of poles and some other things. As with other things, the move to 60 Hz was likely evolutionary and heavily based on the cost to make the change.

There is some historical information that should be able to be found under Edison, Westinghouse and similar names - the people who heavily influence the early and rapid growth of electrical systems in the US. Again, I'd expect Europe and other areas of the world to have been influenced by this (and they influenced the US) but they ended up at different point as a result of a similar evolutionary process.

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stevez

 

Sorry, I don't understand that, I'm probably being very stupid, but why would 60Hz be any better for click syncing than 50Hz?

 

How many seconds in a minute?
How many minutes in an hour?

all they do is tie a wall clock off of the mains and no extra stuff. In the UK it is a bit more tricky (a few more teeth on a cog).


As for maths I would rather deal with 50Hz fundemental when asked what the 320th harmonic is than if the fundemental freq was 60Hz

 

Don't forget Tesla, who was the pioneer of AC and AC machinery, against some other industry giants who were pushing for DC (it's a fascinating story, really!). Just because of some of his more "eccentric" ideas, I think he kind of got sidelined in the history books though I'd say it could be argued that his contributions were greater than the others'.

j.

 

You lost me there. For motor-driven clocks, both frequencies require synchronous motors and gear trains. For digital clocks, you need to divide by 60 or 50 to get to seconds. From there on, both are identical.

 

I mean, Styx talking about the pretty old, full electromechanical wall-clock...

 

That's what I was talking about also. Didn't they have synchronous motors and gear trains?

 

here is an interesting read on the subject:

http://archives.openflows.org/electr.../msg00678.html

seems various mechanical, feasability and compromises resulted in 60Hz in North America. Telsa is credited with suggesting 60Hz to eliminate streetlighting flicker.

 

zevon - nice, thanks!!

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stevez

 

OK. 60 seconds in a minute. 60 minutes in an hour. 12 hours in a 12 hour period. So what? Where does the 50Hz come in? All the mains driven clocks in the UK (formerly England) used the mains frequency as a reference, just like the clocks in the USA, once you got the seconds right the subsequent gearing is surely irrelevant. Or maybe I've got it wrong, and 60 Hz means 60 cycles per minute?

 

The only difference for mechanical clocks is the number of teeth on one gear, it makes no real difference at 50Hz or 60Hz - neither is easier than the other.

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I know, that's just what I've been saying!

 

I was agreeing with you 8)

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