19 Feb
2007
19 Feb
'07
6:46 a.m.
On Sun, 18 Feb 2007 22:46:57 -0800, Brent Hilpert wrote:
"In even later years, solid-state rectifiers of
sufficient capacity for the
traction power industry were developed, and substations became no more
exciting than giant computer chips."
Now there are fighting words. I expect this group would find a giant computer chip of
great interest !
Thanks for the subway link, and to keep things on topic, the IBM 370 family of mainframes
used a MG
(motor genertaor) set to convert the 60hz power from the mains to 3 phase at 400Hz to
allow more efficent
conversion of power in the internal supplies. Both smaller transformars and much smaller
filter caps were
needed to convert and smooth the 400hz to DC.
In fear of sliding too far back on topic :-)
I will point out that the telephone system uses 90v 30hz as the ring signal because it
worked so well with
the mechanical bells used in the early phones.
The other Bob