TELECOM Digest OnLine - Sorted: Re: 25 Hz power Re: Tie Lines was Re: Foreign Exchange Lines

Re: 25 Hz power Re: Tie Lines was Re: Foreign Exchange Lines
31 May 2005 09:30:53 -0700 wrote:

> Doesn't Amtrak still have some 25 Hz power plants from its predecessor
> lines in the Northeast Corridor? Some locations have been converted
> to commercial power, some of them still owned and operated by Amtrak
> still provide 25 Hz.

AFAIK, no railroad generates its own power anymore. Indeed, the great
1930s Pennsylvania RR electrification used commercial power right from
the start.

Amtrak, SEPTA, and NJ Transit still have considerable routes that use
the original 25Hz 11,000V. The New Haven to Boston line uses modern
power as does some NJT routes.

> Their electric locomovies are designed to run on either frequency and
> within a certain range of voltages (24,000 and higher) to accomodate
> the variations in the power supplied by commerical power in different
> sections and also those sections served by their legacy power plants.

The locomotives can switch power on the fly, but many of the commuter
cars require shop work to make the conversion to a different power

AFAIK, today there is nothing wrong with continuing with 25Hz and a
lot of expense and disruption to convert, so it probably will remain
in service for a long time. AFAIK, the substations that convert the
frequency are solid-state now.

A more pressing problem is the poor shape of the catenary (overhead
wires to the trains). It is mostly 75 years old (or more) and time
has caught up. Looking at it, especially at complex junctions, one
can't help but marvel at the genuis of the engineers who designed it
in the 1930s -- its durability is incredible.

[TELECOM Digest Editor's Note: I still recall how Chicago Transit
Authority used to switch between 'third rail' and overhead (catenary)
wires north of Howard Street on the Evanston line and the Skokie
line. Train would pull out of the station (using third rail), get a
short distance up the track, coast to a stop and while they were in
the process of hoisting the catenary pole into place, one or more of
the clerks would walk through the cars like the proverbial train
bandits of old times, telling the passengers "five cents more to
continue your ride, please". People would get in their purses to find
a nickel to hand over, but thoughtful passengers who made the trip
each day and knew what to expect had already paid their five cent
surcharge at the station where they boarded the train and instead of
a nickle for the clerk would produce a a scrap of paper instead which
I think was entitled 'proof of payment' and hand that over to the
clerks instead. PAT]

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