Locomotive

[gswager]

I do understand that the diesel engine runs the generator which creates electricity. The electricity goes to the electric motor for its wheels while some of electricity goes to the cars, powering A/C, heater, lights, etc.

I'm wondering if the voltage in the generators runs constantly while use the engine speed to increase/decrease the amps. Is that correct?

 

[jdwolfskill]

I see that no one has answered your question, so I'll take a crack at it. Perhaps other posters can add more details that are specific to Amtrak locomotives. In the matter of AC generators, you are almost correct. They work on the following principle: The Voltage (E), Frequency (Hz.) and phase angle (in degrees) of the output are controlled by the electronic governor in response to an electrical load (A).

Amperage (A) is a measure of the total current flow from the generator in the process of doing a job such as turning the wheels, lighting the lights, etc. Amperage is modified (not controlled) by opening or closing the locomotive throttle, or turning on a light switch in the dining car. When current flow (amperage) in the system increases, voltage starts to decrease. The electronic governor senses the voltage drop and sends a signal to the diesel engine to speed up, which makes the electrical generator spin faster. The voltage then returns to normal (setpoint), where it remains until another load change occurs.

The electric motors of some locomotives can also serve as brakes, when current is fed to the traction motors in a reverse direction. This is called dynamic braking. DC (Direct Current) generators work in almost the same way.

Hope this helps some.

John Wolfskill

http://www.trainweb.org/metrovalleyline/index.html

 

[AlanB]

In this General Motors EMD 710 series engine, putting the throttle into notch 1 engages a set of contactors (giant electrical relays). These contactors hook the main generator to the traction motors. Each notch engages a different combination of contactors, producing a different voltage. Some combinations of contactors put certain parts of the generator winding into a series configuration that results in a higher voltage. Others put certain parts in parallel, resulting in a lower voltage. The traction motors produce more power at higher voltages.

The above quote comes from the How Stuff Works website located here.

Note the link above takes you to the specific page for the quote above. There are however eight other pages that you can link to from the above page, which cover other aspects of the diesel passenger locomotive.