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Any particular reason for 60 hz?

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Chris Russell

Tue Nov 29 2011, 02:53AM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

Conner's answer is the best -- we just sort of arrived there and it stuck. Once the system was established, any change would have cost far more than would have been saved by moving to a more efficient frequency.

Economics, I'm guessing, helps keep us in the sub-kHz range. A higher frequency means more efficient transformers, but more losses due to skin effect in transmission lines. Consumers bear losses due to inefficient electronics, while utility companies must bear transmission losses.

doctor electrons

Wed Nov 30 2011, 10:42PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

59 hertz turned out to be a waste of time.
So did 61.

BlakFyre

Thu Dec 01 2011, 08:25AM

Registered Member #1563 Joined: Wed Jun 25 2008, 03:55AM
Location: Wimer Oregon, Wewt for sticks!
Posts: 30

doctor electrons wrote ...

59 hertz turned out to be a waste of time.
So did 61.

This.
Not sure if this was the reason... but I do know I have seen many of appliances and other devices use the mains frequency for timing. It seems like the only reasons that make any sense are the ones that relate to convenience.

Ash Small

Thu Dec 01 2011, 10:16AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

A lot of it is due to mechanical reasons, rotating machinery, etc.

3000-3600 RPM is/was the practical limit for large generators when the national grid, etc. was devised.

sbs_2010

Sat Feb 11 2012, 04:17AM

Registered Member #4392 Joined: Mon Feb 06 2012, 01:04AM
Location: Duffield, Va
Posts: 10

HighVoltageChick wrote ...

Because Tesla chose that number. It says in Margaret Cheney's biography of him but i forgot...

BTW the book title is Margaret Cheney's Tesla, Man out of Time.

I read that book too! Did a book report on it in 8th grade! haha. It was a little over the other classmates's heads though, when i was talking about AC vs. DC

haxor5354

Sat Feb 11 2012, 02:17PM

Registered Member #2063 Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352

wouldn't there be a lot of inductive loss if the grid runs on the KHz range?

Tetris

Sat Feb 11 2012, 03:14PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

Inducktion wrote ...

I do love the way 60 hz sounds. Maybe it's also a good thing, as I probably couldn't stand hearing a constant high pitched squeal if the frequency was in hearing range.

If they could change it, do you think they would?

60 hz is in my hearing range... its pleasant but I like the sound of 50Hz better. And I dont think so because a lot of devices are already meant to operate on one or the other. If changed lower or higher, things might get angry fast.

GrantX

Sun Feb 12 2012, 06:07AM

Registered Member #4074 Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335

Would a multi-kilohertz frequency cause huge capacitive losses between transmission lines? As I understand it, as frequency increases so does the current through a capacitor, thus with high frequency a lot of power would transfer between phase lines?

Steve Conner

Sun Feb 12 2012, 09:50AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

The current through a capacitor is reactive, or "wattless" as an old timer might say. So it doesn't represent a power loss directly, except in so far as the power lines have to carry the reactive current in addition to the load current, so the I2R losses are greater.

This is a very big "except". It makes very long underground and undersea cables difficult, because they have very high capacitance, and the capacitive current gets bigger than the load current. They were impractical until HVDC technology came along. DC is transmitted in the cables, with a rectifier at one end and an inverter at the other. In this case, the best frequency was 0Hz

Overhead lines are somewhat different. The capacitance between the lines is very small, and the loop area is large, so an overhead line looks like a series inductance. Again, this is reactive and so doesn't represent any real power loss, but nevertheless it causes the voltage to sag under load. So, long lines have PFC capacitors at the receiving end to resonate the inductance and bring the voltage back up.

If the frequency were higher, a long overhead line might be longer than a wavelength, and really weird stuff would happen.

Inducktion

Mon Feb 13 2012, 07:35PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

I wonder what would happen then.

A black hole would form! LOL

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