neilw
now that's what I call a garden railway
Posts: 284
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Post by neilw on May 11, 2012 10:51:06 GMT
thought for the day.........why do we use the term "traction current discharged" when in actual fact it is the voltage that is switched on and off? Without a train or anything else to draw a current, the voltage is still there........  |
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mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
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Post by mrfs42 on May 11, 2012 11:09:58 GMT
thought for the day.........why do we use the term "traction current discharged" when in actual fact it is the voltage that is switched on and off? Without a train or anything else to draw a current, the voltage is still there........ Good call - it's been in use since the very early days. My 1906 Met WTTs make reference to current switching, and I think they were either the second (Circle) or first (Extension Rly) WTTs after electrification. The earliest C&SLR WTT that I've seen (1916) also uses the term current. |
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Post by trt on May 11, 2012 13:32:07 GMT
V=I*R
Maybe there's a lot of resistance to change?
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mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
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Post by mrfs42 on May 11, 2012 13:36:00 GMT
You saying that there's not much reactance to change then?  |
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on May 11, 2012 14:26:05 GMT
They are known as Traction Current sections so that's why they are called them (even if it's wrong!)
The terms discharg(ed) and charg(ed) shouldn't be used either, instead off/dead and on/alive are what should be used!
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Post by revupminster on May 12, 2012 8:57:56 GMT
I always thought traction current was the best terminology as it is the power that gives the train movement as apposed to signal current. I never liked the word "juice".
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rincew1nd
Administrator
Junior Under-wizzard of quiz
Posts: 10,286 
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Post by rincew1nd on May 12, 2012 9:27:12 GMT
Hmmm, a bit like the debate currently raging here (no pun intended):
Is the strip of land in the centre of a dual carriageway the "Central Reservation" as mentioned in The Highway Code, or the "Central Reserve" as per some bizarre hidden DfT design document.
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Phil
In memoriam
RIP 23-Oct-2018
Posts: 9,473
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Post by Phil on May 12, 2012 22:32:22 GMT
Trains need current to move. You can have a HUGE voltage (remember the Van De Graaf generator from school?) but if there is no current there will not be any motion. So, disconnecting/tripping may remove the voltage but it's the lack of current that stops the trains moving. *Of course, for the specialists, resistance is part of the equation, but electrical power is defined as (current 2x resistance) - voltage does not appear here in its own right . *That's why you can be killed by a mains current at 230V but only get tickled by the Van de Graaf generator at 50 000V. |
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on May 13, 2012 7:53:14 GMT
Of course, for the specialists, resistance is part of the equation, but electrical power is defined as (current 2x resistance) - voltage does not appear here in its own right . But that definition is only a substituted form of the tradional P=VI, used when V is not known but I is: P=VI and V=IR thus P=(IR)I, or P=I 2R ;D |
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Post by torquewrench on May 13, 2012 20:43:41 GMT
de-isolated is another one, ITS REINSTATED! Heard this on the radio one day and did make me giggle!
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roythebus
Pleased to say the restoration of BEA coach MLL738 is as complete as it can be, now restoring MLL721
Posts: 1,275
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Post by roythebus on May 13, 2012 23:25:19 GMT
Hmm, a bit like the conversation between my driver and the depot master when I was a 2nd man at Kings Cross.
DM wanted to know about the "defective fuse" on a class 31 at Potters Bar casuing a dely.
Driver said it wasn't defective.
DM asked why.
Driver says it was Effective.
DM asks why.
Driver says it was Effective because it done what it says on the tin, it blew to protect a circuit from overload.
Had he tried to replace the Effective fuse with a fuse that had already fulfilled its purpose, then he would have replaced the recently blown fuse with a Defective fuse...and so it went on.
Otherwise as a driver I don't care if it's traction current/volts/amps or whatever, as long as I know when it's on or off that's all that matters, and unless I'm told it's off, then it's on and don't touch it.
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