A question that struck me during this mornings study session; Why is it we design electrical systems with 50Hz or 60Hz when the Earth is about 40Hz? We at the company I work for are having a time with the 3rd harmonic distortion in the electrical supply to buildings and I am thinking wouldn't we want to design our supply at 40Hz to resonate with the Earth and thereby get less reactance and harmonic distortion?


The phrasing of my question to Google was;
What is the core frequency of Earth?
Answer: about 40 cycles/sec In other words, the natural frequency of the Earth at the boundary of the inner core is about 40 cycles/sec, which is at the upper end of the range of frequencies measured for the Schumann resonances: 7.8, 14, 20, 26, 33, 39 and 45 Hertz. Schumann Resonances https://www.valdostamuseum.com/hamsmith/Schumann.html

 

Welcome to AAC.
The reason for 50/60Hz is historical. At the beginning, there were many small power companies and the frequency was a matter of the number of poles in the generator and the speed of the armature. While individual companies kept the frequency the same, there was no need for interoperation and no standard. This changed when AC motors became important. The frequency mattered and so it had to be standardized. The choice of 50Hz and 60Hz were effectively arbitrary but in the US, Westinghouse decided that while motors were fine with 50Hz, the flicker in arc lamps was more pronounced so chose 60Hz.

If anything we'd want to increase the frequency of the power distribution system. Higher frequencies means smaller transformers which would be a big benefit. The flickering problem for lighting would also have to be addressed, requiring somewhat larger caps in LED lights and making incandescents much more likely to visibly flicker.

 

Because the closer You get to the Earths natural Frequency, the more problems You would have.
Also, we should have changed over to ~400-hz back in the '40's, or even earlier,
when the Grid technology had progressed enough to make an increase in Frequency the obvious choice.
All the Transformers would be less than half the size.
.
.
.

 

The earth's natural frequency has nothing to do, and has no effect, on the frequency used to transmit electricity in power lines or its efficiency.
Why would you think it does?
No significant part of the power-line current travels through the earth.

 

The earth's natural frequency has nothing to do, and has no effect, on the frequency used to transmit electricity in power lines or its efficiency.
Why would you think it does?
No significant part of the power-line current travels through the earth.

That's not quite true. SWER (Single Wire Earth Return) systems are used in remote areas with just one wire for transmission and the earth as the return. That said, I don't know what mechanism the oscillations of the earth would have to influence the system. So far as I can tell—none. I would like to know what is proposed.

 

we should have changed over to ~400-hz back in the '40's, or even earlier,
when the Grid technology had progressed enough to make an increase in Frequency the obvious choice.

What improvement in grid technology?
400Hz would cause a significant reduction in efficiency over a long distance due to skin effect and other reactive losses at the higher frequency.

 

What improvement in grid technology?
400Hz would cause a significant reduction in efficiency over a long distance due to skin effect and other reactive losses at the higher frequency.

Now that have efficient DC-to-DC conversion technology, wouldn't a DC grid be an improvement?

 

Now that have efficient DC-to-DC conversion technology, wouldn't a DC grid be an improvement?

DC grid, AC-DC -AC long distance DC power transmission has been in effect for decades.

 

One problem that could spring up with DC transmission is switching high voltage DC is a real problem as the arcs are not self extinguishing. Also, electrolysis eroding of parts of the infrastructure, and at the higher volts needed, it would be worse. As in all things, the 50/60hz is a compromise.

 

One problem that could spring up with DC transmission is switching high voltage DC is a real problem as the arcs are not self extinguishing. Also, electrolysis eroding of parts of the infrastructure, and at the higher volts needed, it would be worse. As in all things, the 50/60hz is a compromise.

But keep in mind that HVDC (High Voltage DC) transmission is a thing. Some of the larger ones run as a megavolt for really long distances. It is more efficient than AC, and while there are costs to do it, for some uses the costs are easily outweighed by the benefits.

 

This province had been using it for some time, the original method was Using Ignitrons, now solid state devices are the norm.
Advantages are only two transmission lines instead of three, no end result disaster in the event of lightening strikes, etc to name a few.
It is old technology.

 

This province had been using it for some time, the original method was Using Ignitrons, now solid state devices are the norm.
Advantages are only two transmission lines instead of three, no end result disaster in the event of lightening strikes, etc to name a few.
It is old technology.

Looks like Wikipedia has a very extensive article on it; High-voltage_direct_current

 

DC grid, AC-DC -AC long distance DC power transmission has been in effect for decades.

Canada has a few: Nelson River DC Transmission System comes to mind. Globally there are several including Japan if I recall correctly. Not to wander off topic.

Wow, by the time I post I am well behind.

Ron

 

There is a big DC line from the Columbia River to Los Angeles.
https://en.m.wikipedia.org/wiki/Pacific_DC_Intertie

 

A question that struck me during this mornings study session; Why is it we design electrical systems with 50Hz or 60Hz when the Earth is about 40Hz? We at the company I work for are having a time with the 3rd harmonic distortion in the electrical supply to buildings and I am thinking wouldn't we want to design our supply at 40Hz to resonate with the Earth and thereby get less reactance and harmonic distortion?


The phrasing of my question to Google was;
What is the core frequency of Earth?
Answer: about 40 cycles/sec In other words, the natural frequency of the Earth at the boundary of the inner core is about 40 cycles/sec, which is at the upper end of the range of frequencies measured for the Schumann resonances: 7.8, 14, 20, 26, 33, 39 and 45 Hertz. Schumann Resonances https://www.valdostamuseum.com/hamsmith/Schumann.html

Why did you expect a different answer here than what you got on the other electronics site?

 

There are two HVDC lines between me and Canada... Coal Creek - Dickinson (400kV) and Center - Adolph (250kV).

I believe it was 25Hz that worked best with motors, and many of the earliest lighting-only systems ran at 125 or 133Hz, and 50 / 60Hz was a compromise.

 

https://en.wikipedia.org/wiki/Quebec_–_New_England_Transmission

 

But keep in mind that HVDC (High Voltage DC) transmission is a thing. Some of the larger ones run as a megavolt for really long distances. It is more efficient than AC, and while there are costs to do it, for some uses the costs are easily outweighed by the benefits.

When I joined Marconi as a student 1985, in my year off before university, I was assigned to the department making the test gear for the thyristors used in the UK-France HVDC link. Like all the other students on the project I have the souvenir puck thyristor in use as a paperweight.

 

Canada has a few: Nelson River DC Transmission System comes to mind.

That is where I am getting my power from as I type!.!

 

That is where I am getting my power from as I type!.!

Well then, see it works.

On an unrelated side note Edison started with DC at the first NYC power station. While it took awhile to spread to Brooklyn, NY my grandfather had a house in the Park Slope section. Their early residential power was DC. Grandfather was a doctor so they had the devices of the day. Atwater Kent radio and of course an early refrigerator. When Consolidated Edison switched to AC they gave customers a huge rectifier box to convert the AC to DC for refrigerators. I discovered it in the basement of the old brownstone when I was a kid.

While I saw Edison as a great inventor and bright I also despise him for his business tactics including his electrocution of Topsy the elephant to promote his DC over AC. He was just a low life crooked bum. Albeit a wealthy pile of crap but nonetheless trash.

Ron