General Electric traction motor specs needed: GHM 838

[eeinpa]

Howdy, folks!
Trying to find basic specs on a 1940s GE series field traction motor, model GHM-838-F1. Yes, they are still in use!

All I really know for sure is it is a ~250 Vdc motor. I would like to know its continuous horsepower rating and full load amperage. Every one I have seen has no nameplate. Contact GE or their service centers, you say??? Ha, ha, ha! Oh, I hurt myself laughing!

The only reference I have found is an old military locomotive manual on the web which says "250 volts 410 amps". Ok, is that continuous, 1 hour rating, or what? Elsewhere in the same manual it says the load ammeter goes green (continuous) to yellow (1 hour) at 325 amps. Hmmm. Discrepancy.

Help greatly appreciated!

 

[DickDV]

This sounds like a railroad locomotive traction motor. If it is, you will probably get more info from the locomotive maintenance manual.

This is really reaching but, if you know the locomotive type (sounds like an early ALCO or GE switch engine), you could contact some of the locomotive preservation groups that specialize in that type of locomotive. There is a huge block of knowledge in these groups, some of it going back into the 30's and even 20's.

 

[eeinpa]

This particular model was only used in one GE locomotive, which was a relatively rare industrial model (65 ton). Not too many "foamers" are into such units. The motor was apparently quite widely used in steel and mining industries, hence I think I may do better here.

I also try to avoid the "foamer boards" (railfan sites) like the plague. Too many people who know everything about everything. Since I know nothing about nothing, it's like a matter/anti-matter collision. Ugly!

 

[JERRYROBINSON]

Have you checked with the GE locomotive web site? They are more cordial than you expect.

 

[eeinpa]

I had my local GE authorized repair shop inquiry directly with GE. Even they cannot get an answer. In fact, they can't even really find anyone to talk to about it. It's just a game of voice mail, faxes, emails. Since this is a 60 year old motor and GE really doesn't have much to do with industrial traction motors like this anymore, I really can't imagine that the GE Transportation website people will help. But I will try sending them an inquiry. I rather think I will have better luck with the GE Museum folks, for whom I left a message. Thanks for the suggestion!

 

[Romefu12]

EEINPA
Try contacting the Ozark Mountain Railcar Company at the following link.

http://www.ozarkmountainrailcar.com/ge80toncentercab.htm

They have an 80 ton GE Switcher for sale that still has the GHM-838 traction motors and may have a manual or a better nameplate.

Romefu12

 

[eeinpa]

Thanks, I know the owner of Ozark Mtn and will inquire if he can take a look. Regards!

 

[JERRYROBINSON]

GE still has it's transportation factory in Erie, PA. but it is pretty much dedicated to Variable Frequency AC Traction motors. There are very few of the people who could help you left there. Romeful12 post would probably be you your best bet. There was a retired GE man local who ran the testing lab in Erie for years who was a wealth of information, but he has traded consulting for fishing .

Good luck on your search.

 

[eeinpa]

I sent an inquiry via GE Transportation's website, but which category do I choose? Locomotive parts? That's for current locomotives. Drilling motors? They make DC traction motors, but not the type I want. The problem these days is that all these companies want to neatly categorize things via the web or voice mail h3ll!

Ozark Mtn knows very little about their locomotive. They are probably just brokering it

I've tried to infer something from the characteristic curve I have for the motor, but I can't seem to get any agreement with the 325/375 Amps given on the ammeter, nor the 410 listed as a motor spec. Maybe the limitation was the generator, not the motor...

*sigh*

 

[waross]

Does the motor have forced cooling? If not, is it possible that the rating is speed related?
The lower current when the transposition connections are in series for slow speed running and a higher rating for the higher speed parallel connections.
respectfully

 

[eeinpa]

Sorry, I may not have explained those numbers fully... The operator's manual for one locomotive using that motor says the ammeter green zone (continuous operation) ends at 325 amps, the yellow zone (1 hr operation) at 375 amps. But this could be a generator limitation, not a motor limitation, which isn't applicable in my use, which is powered off a very large rectifier.

There is no forced air cooling, other than the fan on the motor. The manual elsewhere states the motor spec as "410 amps", with no explanation.

What I'd really like is just a horsepower rating with some qualification, e.g. one hour rating, 30 minute rating, etc.

We are just quoting with 300 amp contactors, which is what the system had originally. If we get to the point of installation, we may have to worry more about this in order to size resistors properly.

Incidentally, The GE Museum returned my call and left a message saying they had no info. I haven't heard back from GE corporate (surprise, surprise!).

 

[DickDV]

ee, I don't know just what you are designing (clearly not a locomotive) but even if the ammeter zones end at 375amps, that's really not far from 410amp. Seems to me you would design your system for 410amps with the ability to limit to 375amp if necessary.

If you have the ability to run and load this motor in your facility, you could do some thermal analysis work on the motor loaded at 375amp and see what, if any, thermal headroom you might have.

If I recall correctly, you are going to have to limit current at very slow speeds and starting as well to protect the commutator from distortion and rapid failure. You probably already know that DC motors do not take well to massive currents at near zero speed despite there reputation for slow speed heavy pulling.

 

[eeinpa]

Um... why "clearly not" a locomotive? Actually I am working on the replacement of obsolete electromechanical acceleration control for an electric locomotive. Unlike the GE locomotive in the manual I mentioned, this locomotive is powered off a large rectifier power source. The current limit for the GE locomotive may have been based on their generator (which powered two traction motors). We don't have that limitation.

While I can simply use 300A rated contactors (as the old design did), it is awfully useful to know an accurate FLA for the motors to size the grid resistors. We cannot locate prints showing the resistances currently in the system, and I'm not too crazy about tracing out the filthy and convoluted wiring to more than 20 grid resistors in order to establish present resistance values (which may not even be correct anymore!). I'd rather just have the motor specs and calculate them.

It is impossible for us to remove the motors, and if we did, we don't have the power source to run them and perform thermal analysis. While I'm sure many readers work someplace where that might be possible, I definitely do not!

Thanks for your input.