I received the following by e-mail from a Mr. Jerry Hayward:
Quote
I have really enjoyed your recent postings along with djk and JohnS.

I would submit for JohnS information that both Westinghouse and AEG transmitted ac power in 1891; Westinghouse at 133 1/3 Hz and AEG at 50 Hz.

The Westinghouse history says that by the end of 1892 it had chosen 60 Hz for lighting and 30 Hz for applications where the power was turned into dc.

25 Hz was used at Niagara Falls because the general contractor had already chosen 250 rpm turbines. With 12 poles this got the frequency to 25 Hz which was between what Westinghouse wanted (30 Hz) and what an outside constultant recommended 16 2/3 Hz. This was long before the synchronous clock was invented in 1916. That inventor made a big effort to get the frequency exact so his clocks could be used and this might be what JohnS relates in his posting.

Westinghouse had earlier used 133 1/3 Hz for ac work because his first generator ran at 2000 rpm (Steam engineers liked to have round numbers for the rpm by this time) and had 8 poles. The resultant 8000 cycles per minute or 133 1/3 Hz was good for lighting. But when Tesla came along with his ac induction motor which was optimised for 60 Hz, Westinghouse changed to 60 Hz.

The one thing that I don't know for certain is why Westinghouse/Tesla chose 60 Hz. The Westinghouse history indicates that other engineers chose the frequency rather than Tesla but if true I haven't seen the reasons why they chose as they did. Various things I have read on Tesla suggest that a) he
did a study and decided that 60 Hz was the best frequency and/or b) he was somewhat of a mystic and kook who considered this as part of the fundamental frequency of the universe or what ever.

GE and Westinghouse cross licensed their patents so it makes sense that both worked the same frequencies here in North America.

In Germany 50 Hz was chosen. I don't know why but I could guess that with a 3000 rpm machine (same idea of round numbers for steam engine rpm) it was easy to go to 50 Hz with no Tesla/Westinghouse to insist on 60 Hz. 50 or 60 Hz both work well and once chosen there may not have been enough reason to change to the other frequency for either company. Any thoughts on this?

{Edited to correct name -- My apologies! [Linked Image]}

[This message has been edited by pauluk (edited 09-13-2003).]