[PRCo] Re: Power Off

[Fred Schneider]

To try to put this whole thing differently, it would be as if you fed  
your house, Matt, from two different power companies.

You could easily have the first floor on one company and the second  
floor fed from another power grid.   No problem.   Or you might have  
the option of feeding the whole house either company with a big  
double throw switch, and if the rates changed, you throw switch.

The railways fed their lines from a variety of sources.

Pittsburgh Railways, for example, bought its power mostly from  
itself, i.e. from Duquesne Light Company.   But it also bought power  
on the south end of the interurban lines from West Penn Power  
Company.  (PTM is on the West Penn Power grid just like PRC was in  
that area.)   And where you ran from one to the other, there had to  
be a section insulator and the appropriate power off sign.

In addition, direct current can only be transmitted about seven miles  
from a substation before the voltage drops so much that it can not  
run a car.   Therefore, on the interurbans for example, there was a  
substation at Tylerdale, another at Canonsburg, another at  
Thompsonville, one at Washington Junction, one at South Hills and one  
at Craft Avenue to feed downtown.   Between the areas fed by each  
one, you needed a section insulator and the POWER OFF sign.   If  
lightning struck the wire at County Line, you didn't want it  
affecting every substation!   Or if you shut down one substation for  
maintenance, you didn't want power feeding in from somewhere else....

So every substation in the system had to be isolated from every other  
one.

There are other ways of doing this.   I did make it too simple.    
Thompsonville was actually an automatic substation and therefore  
there probably was no insulator between it and Canonsburg or perhaps  
between it and Washington Junction.   I'm not sure which one it was  
intended to support.  The principal between an automatic sub is that  
it can shut itself down if there is no load, and come back on line if  
the voltage drops below a certain point.   Charlie Shauck, the  
Superintendent of Power and Inclines in the 1950s, told me his first  
job out of college was to install that substation.   I think that CES  
was in the same class at Carnegie Tech with my dad and with Sam  
Lybarger.   He would have graduated about 1930.   That would pretty  
much date when Thompsonville was built.



On Apr 25, 2008, at 2:01 PM, Barry, Matthew R wrote:

> Check out the attached photo of the Carnegie Library on the North  
> Side of Pittsburgh from the streetcar days.   You'll note on the  
> line hangar, a sign that reads:  "power off."   I never knew  
> exactly what that meant.    Did it mean there was no power on that  
> stretch of track and the car had to glide past on whatever power it  
> stored up?
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