Electrical Question

[Mr Mayor]

The book says to keep a minimum of 3.2 bars between
brushes on my 3 brush Delco generator. It doesnt tell you
why. Anyone know?

 

[Janicholson]

My thoughts are that any closer to the Arm brush and the circuits could interact causing a reduction in actual output. Jim

 

[teddy52food]

If the movable brush touches the stationary brush, it will charge full charge.

 

[Jim Becker]

I don't know either. But I always assumed if it was closer it might produce too much current and burn something out.

 

[John T]

Maybe it has something to do with the width of the brushes versus the width and separation of the commutator segments and related to Jims thinking, 1) If too close the field current may be too high orrrrrrrrrr 2) The brushes might interfere with each other ?????? Maybe some kind gent with time will research it and tell us all the answer..

John T

 

[Mr Mayor]

Hey John, on a different note. You answered a post of mine from earlier in the month concerning non charging genny and linked to your troubleshooting guide. I've done every test and all things point to the generator itself. I tried a different genny with my cutout and all is perfect. The generator motors, no charge, and when I close the points manually the ammeter bottoms out to discharge. Is there anything I can check with a multi meter? Geoff

 

[teddy52food]

It has a flying short in the armature.

 

[Mr Mayor]

Please define flying short

 

[Jim Becker]

A short that only shows when the armature is spinning. Or maybe it means landing before reaching the runway?

 

[teddy52food]

A loose wire in the armature that moves from centrifical force & shorts to ground.

 

[John T]

Sorry got here late. Often (NOT always) if the genny passes BOTH motor tests it will charge. However there can still be maybe commutator or armature problems its hard to say from here...

ALSO I like Teddys approach, he may have it, as things can work at LOW RPM (even pass BOTH my motor tests) but up to speed shorts or wiring may show up due to vibration and centrifugal forces on the windings

Yayyyyyyyy Teddy

John T

 

[Mr Mayor]

OK, It failed part two (speeding up) when removing jumper. I wasn't sure if the cable from the light switch to F stays connected for this test so I tried the jumper to frame with and without that wire connected. Geoff