Electric locomotives with on-board fueled prime movers, such as diesel engines or gas turbines, are classed as diesel-electric or gas turbine -electric and not as electric locomotives, because the electric generator/ motor combination serves only as a power transmission system.
Electric locomotives benefit from the high efficiency of electric motors, often above 90% (not including the inefficiency of generating the electricity ). Additional efficiency can be gained from regenerative braking, which allows kinetic energy to be recovered during braking to put power back on the line. Newer electric locomotives use AC motor -inverter drive systems that provide for regenerative braking. Electric locomotives are quiet compared to diesel locomotives since there is no engine and exhaust noise and less mechanical noise. The lack of reciprocating parts means electric locomotives are easier on the track, reducing track maintenance. Power plant capacity is far greater than any individuallocomotive uses, so electric locomotives can have a higher power output than diesel locomotives and they can produce even higher short-term surge power for fast acceleration. Electric locomotives are ideal for commuter rail service with frequent stops. Electric locomotives are used on freight routes with consistently high traffic volumes, or in areas with advanced rail networks.
