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Hi, the website www.trainweb.org is very interesting i found for explaining exactly how a train works. I can understand that basically a train can go in reverse (an electric train) by reversing the polarity of the current in the case of DC to the traction motors, but how does an AC electric motor go in reverse if required to by the driver, most are 3 phase now as this is a much lighter motor and seems to be more efficient.
i found it interesting learning how the drivers controls vary the speed of the train by variable resistors and varying the taps on the transformer for AC current, etc.
This is an interesting website I find, the above website link is more suitable for trainee engineers, etc.
cheers...
barrydraper Member # 737
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Without getting too technical, 3 phase AC power has 3 wires with the rise and fall of the AC voltage delayed by 60 degrees in each successive phase and wire. The direstion of a 3 phase AC motor is determined by the order that the phases are connected to the coils. On an AC locomotive the phases are "created" by an electronic inverter, so it is easy for the computer to change the order of the phases.
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