13 Dec
2004
13 Dec
'04
10:47 a.m.
I don't actually know where 50 and 60 Hz came
from, nor 100 and 115
and 220 and 240 volts. There may be some ancient justification in the
tinkerings of various 19th century engineers, but it seems to me it
makes most sense simply to view them as random numbers.
paul
With a simple two-pole machine, 50Hz is acheived at 1,500rpm which is a
nice round(-ish) number. Obviously a six-pole machine will produce a 50Hz
three-phase supply at the same speed, and 60Hz at 1,800rpm.
Now, 1,500rpm is quite a good speed for steam engines and the like, and
it's possible to make direct-drive hydroelectric turbines that run at that
speed, very efficiently.
Gordon.