Home Forums General Discussion Technical Questions Otis UCLS MG Set Issue

So I've got a dinosaur I'm trying to get going until new controllers come in. As far as the circuit goes the unit acts like it wants to run. It's in the overhead, I've got the final jumped out and I've got a down direction sealed in, I can even see the brake picking. When we took the job over the brushed hadn't been changed and the commutator was damaged. We had the generator repaired and hooked it back up but not sure what else needs to happed. On the print it looks like I'm having issues around area 15 when I get into GF5. Not sure if this unit is a 10-21 or 30 the prints I've got say they're good for all 3. Any help is much appreciated.

Not sure if this is your issue, but years ago when a generator was repaired, even with new brushes (and attempted seating) the compounding was so far off that the unit would stall in one direction or another. One trick we used was getting a piece of clean pine wood about the size and length of a paint brush handle and run the clean flat end over the running commutator bars to glaze them over a bit. It worked, but the series field then had to be adjusted for good up/dn leveling, and rechecked as the brushes truly seated in.

Things to check. Do you have motor field from the rectifier? If the Genny is spinning and you have Generator self-excited field current, you should have voltage at the generator brushes, to the motor brushes, and if you do the motor will turn. This is all predicated on the Genny being wired correctly. As elmcannic stated, when you get it running compounding is critical. It should run the same speed up and down in leveling with a balanced load. Generators are complicated. Brushes need to be seated, the series field needs to be correct. Some Otis units had separate fields for leveling. this is something to check as the leveling field was put into play with a contact from one of the speed switches, like FE or 1E. Good Luck.

I would really dig in on that generator wiring since it had gone out for repair. Some Otis gens are extra complicated and it helps to have the end diagram for the particular unit. This sounds similar to an issue we had after a rebuild. Found 1 field pole wired backwards, may have been in the leveling field, been a while. I’ve also seen one come back with neutral so far out that is wouldn’t level down. I make it a habit to set Neutral myself when we get a generator back.