External120 VAC to The Precharge Board

I am replacing some 1336 force drives tonight with some PF 755 drives. I notice on the large 50 hp drives there are 120 vac breakers coming off the 480 x 120 control transformer and going to the precharge board on each drive the smaller hp drives do not have this?

I can' seem to find anything in the manuals that i have and can get online that say anything about this. Any Ideas?

Is that separate control power for an active front end?

I don't have a 755 manual saved here.

What are the terminal numbers and the whole catalog number?

I am sure someone can look it up...

Kid
Are you sure the 120 goes to the precharge board and by that you mean for precharging capacitors on DC bus?

How do they charge capacitors that are normally at around 700 VDC with only 120 VAC? Something does not sound right - would have to read the manual. Are you lucky enough to have accurate prints?

Dan Bentler