In article , D.M. Garner
writes
The real advantages of the modern AC traction systems over the older
DC systems are the following:

1. DC motors have brushes, which cause mechanical noise and which wear
out and have to be replaced; AC induction motors do not.
2. You get more power per kg of motor with AC induction motors than you
do with DC motors.
3. The control of Ac induction motors is done entirely electronically - there
are no mechanical parts (eg, relays, tap-changers) like the old DC systems
have and, again, which wear out quickly.

Plus, surely, no resistances in the circuit (and wasting power) at other
than full settings.

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Clive D.W. Feather | Home:
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