Engine Electric's

Trains Magazine General Discussion
1

I have some questions on Diesel Locomotive’s. I do not work for the railroad so some of these question might seem pretty basic to some of you.

  1. How much voltage will the generator on a SD-40 produce. Is there a max and a min. votage it is able to produce?
    2.Are there circuit breaker between the drive motors and the generator? What are they rated at?
    3.If a drive motor burns out or has a short can it be replaced quickly
    4.how often is the electrical wiring replaced on a engine?
    5.How often are the generators replaced on a engine? Do they go out often?
    Thank-you
    TIM ARGUBRIGHT
2

Hi Tim,
I will give it a try, but I am sure there will be someone with a little more detailed answer.
1: First, its not a generator, its a alternator, just like in your car, only huge. It produces 600 volts a/c, the current is passed through a rectifier to convert it to d/c. Most produce up to 1800 amps,(electrical pressure), which is whats counts.
2: Yes, there is. Its called a ground fault relay, and trips if the traction motors or the alternator overloads or shorts. Rated to 600 volts.
3: No, its a real pain in the keister. Requires the locomotive to be in the shop for a day or two, depends on your shop force.
4: Almost never, unless its part of a entire class electrical upgrade, as in the SD40-2s, where the entire line of SD40s received modular electronics, and some of the older units were retrofitted at the same time. The -2 means the unit was either built with new, modular electronics, or is a older unit thats been upgraded, same with the GP38-2.
5: Again, almost never. We have had our MK1500 Ds for 7 years now, almost constant use, and have yet to lose a alternator. Funny, the alternators in our motors are made by…KATO.
Yup, the same guys who make model trains.
Even has the same logo on the data tag.
Stay Frosty,
Ed

3

Hi Ed, good answer, I,ve never measured the
voltage from a SD-40 altenator, but on a SD70MAC
the voltage can rise to 2600V and spike as high
as 3000V, also, by the way, in electrical terms
voltage is usually thought of as the “pressure”
jackflash

4

Though amps were pressure, and volts were volume?
Oh well, either way, its a lot of juice to mess with.
Stay Frosty,
Ed

5

With that much voltage running thruogh a rectifier there has to be a lot of heat produced. What keeps the electrics cool? With the traction motors being so low to the ground how do they stay cool?
TIM A

6

Traction motors have blowers, filtered and ducted to bring outside fresh air in and cool them. The rectifier and related “stuff” is in a compartment, usually right behind the cab, also with its own blower, filter and cooling system.
Stay Frosty,
Ed

7

Hi again Ed, Voltage is the measure of electron
pressure. Current,mesaured in amps, is the flow
of electrons. jackflash

8

Voltage and amperage sort of sounds like the size of a river and how high and fast the water is flowing.
As for cooling, I don’t imagine it hurts to have someone named blysard in the cab keeping things nice and frosty!
Sorry Ed…Couldn’t resist after the day I had. Needed a good laugh. No malice intended.

9

None taken.
Every time the temp drops down here, well, you can guess how much fun the other guys have…
Stay Frosty,
Ed

10

Can guess more than you know. My last name is even more conducive to puns and witticisms than yours. Growing up was a lot of fun to say the least. Ask the right questions and I might even let you figure it out. Will have to think about it though since this is a public forum.