At what Hz to traction motors operate at? Standard 60? Is it the same from the early GP-38AC to today's 70 MAC's? Is GE's the same and can EMD and GE AC traction motors interchangable?
Thanks, Chuck
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This should answer your question on asynchronous electric traction motors.
As far as GE vs. EMD. They are different squirrel cage motors with slightly different configurations, design, and different ratings such as torque. I doubt that you could interchange them since the locomotive's circuitry and programming is designed for the specifications of the specific motor being used.
FYI, the GP38AC wasn't AC traction.
The type of AC motors used as traction motors (SD-70 MAC in your example) have a rotational speed that is proportional to the frequency (higher the frequency, the higher the speed). To vary the speed of the motors, these locomotives utilize a whole host of electronics to turn DC into a variable frequency AC for the motors.
AC traction motors do not operate at a fixed frequency. The speed of the motor is changed by changing the frequency at which it operates. When first starting a train, the frequency might be only a few hz, and as the train accelerates, the frequency goes higher and higher.
I don't know the frequency range involved, but the principle of operation of an AC traction motor is changing frequency.
As pointed out above, the GP38AC was not equipped with AC traction motors. It had an AC alternator producing the tractive power, and that was where it got the "AC" in the model designation. However, that AC power was rectified and fed to standard DC traction motors.
To add to Rich's explanation, above, both the EMD and GE AC Traction Motors are three phase induction motors.
Thanks guys! I have a clearer picture of how they work now.
Chuck
