This is probably a long shot, but I'm looking for help with a SD40-2 locomotive that is only making about half of its capable horsepower. I'm an electrician myself and this is a problem that is usually an easy fix. Quick back story of the problem.. a coil fell in the main gen at full load, destroyed the gen. The locomotive is then brought to our shop (this is a customers loco) they get us a new to them gen..Ar10-7A. Which is not the same as the original, (Ar10). We get it all installed, load box it, and it only makes 1500 Hp. With out getting into everything we have checked/tested, if there are any experienced locomotive techs/electricians out there. Please send me a PM. Need help! Or we can discuss on this thread if anyone's is interested.
ONRelectrician This is probably a long shot, but I'm looking for help with a SD40-2 locomotive that is only making about half of its capable horsepower. I'm an electrician myself and this is a problem that is usually an easy fix. Quick back story of the problem.. a coil fell in the main gen at full load, destroyed the gen. The locomotive is then brought to our shop (this is a customers loco) they get us a new to them gen..Ar10-7A. Which is not the same as the original, (Ar10). We get it all installed, load box it, and it only makes 1500 Hp. With out getting into everything we have checked/tested, if there are any experienced locomotive techs/electricians out there. Please send me a PM. Need help! Or we can discuss on this thread if anyone's is interested.
Just a suggestion: might try and re-post this question on the General Information section of the TRAINS Forum... I think you posted it correctly, but it might also be posted as I suggested...There are several Posters there that might be able to helop with your problem. Just my thought.
Many people would be interested. Go ahead and post what you've already done.
Start with load regulator position at notch 8 full load.
Randy
Randy StahlMany people would be interested.
I am one. Is there a functional difference between analyzing a GP40-2 and an SD40-2?
Go ahead and post what you've already done. Start with load regulator position at notch 8 full load.
This is going to be an education not only in the electrical system of a Geep, but in the way skilled people teach.
After a week of troubleshooting and qualifying everything. The feedback circuit was B/O. when first tested the three CTs in the gen were good. later after taking a voltage reading at some test points, 2 of the three CTs were not in spec, we changed all thee of them and it's working now. We will load box it Monday.
Something doesn't sound right. If the issue was only bad CTs the locomotive should be overloading.....
You're right. It would be overloading. im on holidays until tomorrow so I'm not sure what happen on the load box today. if the problem is not fixed I have no idea where to go next.
here is what we have done.
We started with confirming all control wiring going into the gen. resistors, capacitors, CTs.
checked all the fuses and diodes. All good.
we changed all the modules. Good.
Checked if all the phases are balanced. Good.
mechanical side seems to be good.
the load regulator goes full field in notch one, then from 2-8 it balanced between 7-9
im sure there's other stuff I can't remember checking. this has been a nightmare.
We cant confirm this gen even made horsepower to begin with, the customer bought I from the States.
the only thing we haven't done it independently excite the gen to see if it's putting out.
Abu suggestions or other questions?!
thanks
Something is still not sounding right. If the engine is only making 1500 HP the load regulator shouldn't balance at all , it should be stuck at max field.
Are you using load test on the locomotive or using an external load box?
we have done both. I wasn't there for the self load test. They thought it was making 3000hp with the self load, the customer was there doing the calculation from the milivolts the shunt. We put it back on the external load box and the meters still only read approx 1500hp.
The load regulator definatly balanced out.
when we drive the locomotive with full breaks and pulling a few cars, we can get the amp meter to like 900+ amps and it might go higher if we had a longer test track. It feels good, that's why we are so confused.
on a side story, the customer had a locomotive freeze and another onewent down so they are going to take this one and give it a go. Like I said, while moving it sounds good and feels good.
im answering you right away but apparently all my posts have to be approved.
I hope somebody wrote the numbers down.
What are the MG volts and the shunt millivolts?
1110 MGV and 23.5 millivolts Notch 8.
This was on self load mode. Which to my calculation is roughly 3000hp
While on the the load box it was about half that. I think we may have paralled the dynamic break with the load box. We will have to hit the prints and see how to hook it up otherwise.
We sent it out this morning and it's pulling like it should. so I'm pretty sure we frak'ed up hooking It up. Hopefully anyways.
Hooking it up is easy, you need to remove a bus bar on the negative bus, hook the load box cables directly to the bus bar. You will see the holes and studs for attachment. Remember , you can't loadbox unless the bus bar is laying on the floor.
Its making 2981 horsepower. Pretty good !
When you said the load regulator is balancing that was the clue that it was making much more than 1500 HP
so remove the bus bar on locomotives with dynamic breaking? the only locos we own with DB are our SD75s and they have a self load on the computer.
When we load box our other units we don't have to remove and bus and we have never came across this problem. thanks so much.
keith
For external loadbox I would remove the bus bar on both dynamic and non dynamic units. I like that positve seperation that comes with having the main bus bar to the traction motors laying on the floor.
I prefer self load test.
Is the altenator getting full excitation? Could a rectifier diode be open? Seems strange to only be producing 50% power.
How about just a loose connection somewhere?
Is there a good clean 'ground'. Can't count the number of vexing electrical issues that have ended up being caused by a less that good and proper ground connection.
Grounds are taken for granted - they shouldn't be.
Never too old to have a happy childhood!
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