6 volt generator

[altair]

I have disassembled a 6 volt generator and I would like to know if the laminated irons inside maintain a moderate level of residual magnetism or not. Currently the one I have has no residual magnetism at all. Will it re-generate its own or will the cores have to be re-magnetised? I should know this but I have forgotten everything I learned in high school.

[StudeRich]

Wouldn't they be fine after you assemble and Polarize the System?

[Chipmaker]

If I member right,the armerture has no magnetism. the field coils may or may not.This is why thay need to be polarized after any of the charging circuit is disconnected.

[altair]

I did some further research that I should have done before, in a generator the field poles maintain a very slight amount of "residual" magnetism, sufficient to create the needed lines of force for the armature to "cut" and induce the (EMF) through the commutator. Therefore there would be no need to re-magnetize the field poles. On the generator I have there is a very slight magnetic pull on the pole cores, from my research this should be sufficient for the generator to operate. Polarizing is to confirm direction of the current flow, this generator is its previous life was off a GM product with a negative ground, therefore will have to be polarized to change the direction to positive ground. When spun on a test bench the generator failed to produce any current therefore I disassembled the unit to further investigate and there was evidence of the armature scraping on one of the field poles, however the condition had been corrected with a new bushing. The armature was tested on a "grawler" and it indicated good. Further into the wiring assembly there was evidence of a brush wire contacting the commutator and possibly creating an unwanted ground the insulation was pared away and the conductor was exposed. I am of the belief now that the pared with exposed conductor was the only problem. I will be reassembling the unit and testing it to day.

[Chipmaker]

For what its worth,you can check a gen. by connecting it to a battery.It should run like a electric motor except slower.
if it does its good to go.

[TWChamp]

For what its worth,you can check a gen. by connecting it to a battery.It should run like a electric motor except slower.
if it does its good to go.

That's a good first check that the generator needs to pass, but I've had a couple of generators for customers that motored when polarized, but still failed to work correctly.
It's always a good idea to polarized a generator that's been worked on.

The residual magnetism in a Model A 6 volt positive ground generator will put out 1/2 volt with the field disconnected.

[altair]

I reassembled the generator and re-tested and it still failed the shop spokesperson suggested the problem may be with the field. The scrubbing of the armature with the field pole was excessive and caused considerable blue coloring of the armature. This would suggest there was excessive heat generated and possibly internal wiring damage. The armature did however test good on the "grawler" but maybe that test is not conclusive.

[rstrasser]

If I recall correctly the growler test for a shorted armature not a open in the windings. You said the armature was blue; any sign that it threw solder. If so the armature is NG.
Ron

[TWChamp]

Ron is right about the growler testing for shorts but not opens. When I test Model A armatures on my growler, I also test for the AC voltage generated by using my multimeter across the commutator bars, as I rotate the armature on the growler. Also be sure to test the armature windings for shorts to the shaft. I also test the field windings for shorts to the case. I test the field windings current draw by using my 6 volt battery charger with an ammeter. Model A field windings draw about 4 amps, but I don't recall how many amps my Studebaker field windings used.

[altair]

If I recall correctly the growler test for a shorted armature not a open in the windings. You said the armature was blue; any sign that it threw solder. If so the armature is NG.
Ron

There was no evidence of it throwing solder

[altair]

This is how much it was scrubbing on the pole, the armature was blue from the friction but there was no solder melted. The grawler test was very quick and preliminary and most likely non conclusive. I think this is a big paper weight resembling a generator.