3-phase power; was: cctalk Digest, Vol 88, Issue 2

[Chuck Guzis]

On 1/4/22 4:04 PM, Grant Taylor via cctalk wrote:

> I knew about 50 and 60 Hz and DC growing up.  I learned about 400 (?) Hz
> being used in military applications about a decade ago.  25 Hz was a
> surprise to me over the last year or so.  I read some interesting
> things, much of it related to Niagara Falls and other power systems
> modeled after it.

400Hz of course, could be encountered if one shopped war-surplus
airborne electronics.   I still remember adventures on Chicago's S.
Michigan "Surplus Row".

Word was that the original plant acquired a generator from a bankrupt
carnival operator in the 1910's.  But it was used all over the place; my
job was with the pyrometer (instrumentation) department.

It was incredible seeing the lengths that were taken to avoid using 60Hz
power for things like a chart recorder.   It was explained that the 25Hz
power was generated on-site from coke oven gas and so was essentially
free, while the 60Hz was purchased from the local utility.

DC, of course, was used for overhead cranes and welding.   Every shop
had outlets with yellow labels indicating the voltage and frequency. You
could plug a coffeepot or hot plate into the 110V (not 120 or 115 or
117) 25Hz outlet, but  beware of using it for much of anything else,
save lighting.  BTW, you have seen no more irritating lighting than
mercury-vapor lamps running off of 25Hz.   Even in our shop, which used
220V 25Hz incandescent lighting, you could see the pulsation.

I did discover that you could take a 110V 25Hz induction motor fan and
plug it into 230V 60Hz for a real kick in performance...and probably
shorter bearing life.

440V/460V 3-phase in both frequencies were in most shops.

Said plant has long since vanished.  This was the day of blast furnaces,
open hearth furnaces and all the stuff that it fed, like merchant mills,
hot- and cold-rolled sheet, tinplate, galvanized...all from a bunch of
rocks.

--Chuck