Care and feeding of DC machines

[nickelbender]

Here goes my first post:

Some GE field service tech's will be in town on Saturday here and I will be doing the PM's on a 5000hp DC machine with them. If anyone is interested I could ask them for some tips and might even bring in my camera to show any readers here steps involved in cleaning, undercutting coms, stoning and what ever suprises we find in the "Big Guy" Saturday night. I will also be doing a Station Garrantee, weather permitting I'll snap some photo's of the shut down and opening the big arc horns of a large industrial substation(we may get to see Corona effects of high voltage also known as "St Elmo's fire" ).

[georgeodjungle]

what kind of grease and oil they use?

do they wash and wax-em?

[maker of toys]

what do they use to keep the brushes free in the guides in a sub-optimal environment?

[nickelbender]

Man am I tired....

Here are some photos (I took lots and a few MOVs.... I would be nice to find some place to archive these here for reference. You just won't see this done very often)

http://www.otherpower.com/images/scimages/4519/100_6715.JPG

http://www.otherpower.com/images/scimages/4519/100_6706.JPG

http://www.otherpower.com/images/scimages/4519/100_6688.JPG

http://www.otherpower.com/images/scimages/4519/100_6715.JPG

After I get some rest I'll be ready to explain and answere questions

[nickelbender]

Ok...

now if you are refering to what types of lubes we use on bushing in the skip motor/drum/cluth assembly we use a #2 NLG grease fortified with Moly (manufactured by EXXON).

As far as the com itlself is concerned we are most concerned that it not get contaminated by any sort of lube or waxes. This motor is forced air cooled so dust is a major issue along with everthing that could be carried in with it. We use a large stack of furnace type filters (10 by 12 feet).

The actual stoning you see here in these pictures is being done with an ajustab;e rig to mnove it back and forth to evenly remove copper. This process will take 40 hours and the last pick you see was taken 12 hours in just before the stones were about to changed for a finer abrasive in a softer matrix. If you look very closely you will see this is an 8 pole machine and I have removed the brush assemblies from 7 of the poles because we are running this machine unloaded and don't want to needlessly wear out an entire set of brushes.

Any other questions?

[nickelbender]

Thats a very good question....

 At another plant where I worked we had a smaller machine that often had that problem. My solution was "Perc" a solvent used in products like brake clean and a 12 g shot gun cleaning brush. This was only a band aid solution the real way to prevent this would have been to install and air filtration system such a the one used on surface. The main idea here is to keep things clean and use inspect often. The men from GE had no solution to your problem than as I already stated control contamination.

[adelaide]

wow wonder if it can fit in a car hahah what rpm and specs does that have ?

[nickelbender]

This machine is an 800 volt dc 7000 hp(the main hoist is a smaller 5000 hp unit I goofed...) 8 pole shunt machine that turns at 50 rpm powered by two GE silpac drives in tandem. For stoning we reduced the speed to 12 rpm and limited the current too 200 amps (thats as low as the drives would allow lol!)

FWI:

There have been some questions around here about 6 phase power. This machine is running on rectified 6 phase produced by a little transformer trickery. The master drive and slave drive are powered from a transformer with two secondary windings. The master is feed from a Y and the slave from a delta. This alows for smoother opperation with less AC chop...

I got the call last night at 8:00pm to reassemble the brush packs. Stoning was completed at 9:00pm and this afternoon the machine is back in service. More photos to come.....

[Drives]

I'm curious, what brand of drives are feeding the DC motors?

[nickelbender]

The drive system is called "SILPAC" manufactured by general electric. This drive is old early 80's stuff but its been quite reliable.

I need storage space for the complete picture set and movies of this job. Does any one have any place I could post this stuff for a while?

 

[TomW]

nickel;

Just stick them in your files area on the board. The link is in that second menu box over on the right there ----->>>>

If you need more room ask danf to bump up your space allotment.

Cheers.

TomW

[nickelbender]

Hmm....

I'm trying but for some reason I can't get the files to transfer.

[willib]

yeah

http://www.putfile.com/

will store your videos for free.