- #1
artis
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Every time I take a train I sort of think about this, so the electrified overhead wire (DC or AC) and the rails form a transmission line and the train is a load that moves along the transmission line.
Let's talk about the DC case as it seems more simple, so when the train is at or near a substation feeding the overhead wire the resistance is low as there is not much distance of wire but when the train is at it's furthest point from each two substations or far away doesn't the train become very inefficient?
The local DC line is 3.3Kv, I am not sure of what the overhead wire is made up (stainless steel strands with aluminum outside?) but the rails are iron and rusty and connections etc , given that current flows in a circuit and the rails form the return path of the circuit what is the approximate efficiency of the train ?
Also if the overhead line is thousands of volts (27Kv in the AC case) above ground and rails have high resistance then aren't the rails close to the train at some rather high voltage with respect to ground?
Let's talk about the DC case as it seems more simple, so when the train is at or near a substation feeding the overhead wire the resistance is low as there is not much distance of wire but when the train is at it's furthest point from each two substations or far away doesn't the train become very inefficient?
The local DC line is 3.3Kv, I am not sure of what the overhead wire is made up (stainless steel strands with aluminum outside?) but the rails are iron and rusty and connections etc , given that current flows in a circuit and the rails form the return path of the circuit what is the approximate efficiency of the train ?
Also if the overhead line is thousands of volts (27Kv in the AC case) above ground and rails have high resistance then aren't the rails close to the train at some rather high voltage with respect to ground?