Re: Hidden Tesla Technological System

Tesla decided on a sixty Hz. frequency because it was easier to design electric clocks with gearing related to 60. Think seconds...

He was asked to think of a 50 Hz system, but declined, even though 50 would be a bit more 'Metric' in nature. The sixty also allowed a bit of a saving in transformer cores and such like.

mike

So... why not 100Hz? Too lossy back when this was all being seriously considered?

..

ould

ing

It wasn't divisible by 3 like his hotel room number, number of laps he swam at the pool, etc.

(((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))) William J. Beaty

Also there is a Schumann cavity mode at ~59.8Hz.

Only one trouble: Tesla forced through this standards change from

(((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))) William J. Beaty

The story I heard many years ago had to do with the losses in the silicon steel available at the time. Magnetic loss, such as eddy currents and magnetic hysteresis, increases with frequency.

As I heard it, Europe didn't have as good transformer steel at the time, and so 50Hz was a better choice. Once set, it is hard to change.

-- glen

For equal magnetic flux, hysteresis loss is proportional to frequency and eddy current loss is nearly proportional to frequency squared.

However, volts per turn is proportional to frequency, hysteresis loss is approximately proportional to flux squared, and eddy current loss is proportional to flux squared.

So, for equal volts per turn, hysteresis loss varies roughly inversely with frequency, and eddy current loss is constant to varying slightly inversely with frequency (due to skin effect).

Transformers get less lossy and more useful as frequency increases, until stray inductances and capacitances get problematic.

In sci.physics.electromag Don Klipstein wrote: (snip, I wrote)

The reason why aeronautics uses 400Hz, and the usual PC switching power supply, with a ferrite core transformer, run about 20kHz.

I was wondering some time ago about the optimal power line frequency for ferrite core transformers. (And I have no idea on the relative cost.)

-- glen

Westinghouse also decided on 60Hz but, at the time, he had more business clout than Tesla so he is commonly cited. How much effect Tesla had on Westinghouse at stage of the game is an open question. There were several systems in use from 16.33 Hz to 133 Hz. 16 and 25Hz were commonly used for industry because of need for lower speed motors driving multiple loads through belts. Some 25Hz generation was still in use at Niagara and in cities like New York and Toronto until the 1960's-70's or later. lamp flicker was unpleasant 16.33Hz is still used for electric railways in many areas (1/3 of 50Hz) 133Hz was considered nicer for lighting than the lower frequencies as flicker is eliminated. 50 and 60Hz were a compromise- a balance between lighting and motor needs. The actual choice between 50 and 60 Hz really was a judgement call made differently in different places (hey, if the Brits went 50Hz, the US would pick 60Hz). In Japan it turned out to be a matter of which salesmen, British or US, had the edge in a particular part of the country- so part is still 50Hz and the rest is 60Hz. Modern electronics made the interconnection between these areas feasible. Differences in gearing are not really a problem: 60/1 vs 72/1 gear ratio (for the second hand -2 pole motor). The rest is the same. Differences in core size- not a big deal but favours 60Hz slightly but initially drive technology favoured the slower generator speeds needed for

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"m II" wrote in message news: snipped-for-privacy@news.x-privat.org...

On 10-11-16 01:44 PM, wbeaty wrote:

Tesla decided on a sixty Hz. frequency because it was easier to design electric clocks with gearing related to 60. Think seconds...

He was asked to think of a 50 Hz system, but declined, even though 50 would be a bit more 'Metric' in nature. The sixty also allowed a bit of a saving in transformer cores and such like.

mike

I don't know, but skin effect would affect the price of the long cable runs. You also have losses related to induced motion in the cables. It's not just transformer losses.

Clifford Heath.

(snip 60Hz vs. 50Hz)

I remember touring the Lake Shasta power plant when I was young, maybe about 6h grade, and being surprised to learn that the generators run at 20rev/s, so six pole. I probably didn't know about more than two poles at the time.

Then much more recently on the Grand Coulee tour, I was again surprised to learn that they run at 72RPM. They are much bigger, so I suppose they couldn't really go at 3600RPM or even 1200RPM, but I wouldn't have guessed 72.

I was then wondering if one could measure the pole non-uniformity by looking for subharmonics in the AC waveform, presumably with a lot of averaging.

-- glen

One consideration is that when you start dealing with the kinds of currents involved in power supply infrastructure, skin effects, which can be usually be ignored at such frequencies, can be an issue because of the sizes of the conductors required. The higher frequency reduces the size of conductors that can be used without requiring skin-effect mitigation techniques.

Sylvia.

m II schrieb:

Hello,

Bye

Duh? 100, just like any other number IS divisible by three. The result just isn't an integer.

Cheers

Ian

The expression "divisible by x" is conventionally understood to mean an integral number of times, since otherwise the expression would have no purpose as it would, as you point out, apply to any number.

Sylvia.

Isn't there some expression like "evenly divisible..." or some such, to disambiguate the phrase?

Cheers! Rich

glen herrmannsfeldt schrieb:

Hello,

are you sure with 72 RPM? 75 RPM are also possible.

Bye

Clifford Heath schrieb:

Hello,

there are heavy problems with the Ferranti effect when using frequencies of about 1 kHz and more on long transmisson lines.

Bye

If I recall, Edison's distribution was horrible. Ten or twenty miles? Compared to that, anything was an improvement. It doesn't seem very likely they were considering two thousand kilometer long grids back then. Now, we're stuck with the frequency, so they're using super high voltage DC for longer lines and reconverting to AC on the receiving end.

mike (the schrieber)

In sci.physics.electromag Uwe Hercksen wrote: (snip, I wrote)

Putting "grand coulee" RPM into google, the first one I find, including pictures of building the dam and generators, has one indicating 120RPM, for one built in 1943.

There are now three power plants, the third one built around 1968. It is the third that runs at 72RPM. Three 600MW and three 700MW turbine-generator units, 615385kVA at 97.5% power factor. Each rotor is 60ft (18m) in diameter.

-- glen