swapping out elec. motor on LT40E15, and sizing rotary converter

[Kelvin]

Howdy all,
don't know how to contact sparky directly, but maybe others have done this.  I've got a 15hp LT40 that is kinda whimpy, i've got a nice 20hp motor sitting in the mill shed.  Any thoughts on just swapping them out electric wise on the mill?  Are they all tailored to specific motors as i know they come with a 25hp on the super.  It would be great if i could sneak the 20hp on it and not overload the current electrics.  I was thinking of buying a whole new mill, but this might be easier.

On another point, my rotary converter is based on a 20 hp motor and suppose to run a 15hp load motor.  I've heard about adding another idler after i start the 20hp.  Any thoughts on whether i should just build a new converter on a 40hp motor i have, or try make my current one work?  I kinda hate to build another b/c this one is based on a static converter i bought at auction that is a $4k Ronk converter with 200 lbs copper coils that are suppose to make a really pure 3 phase.  If i use the 40hp motor i'd buy a cheap static from ebay for $600 bucks and stick them together.  Any thoughts here?

[jdrum]

manufacturers usually add some over kill in sizing stuff, i would stick the 20 on the mill, and run it and keep an eye on the wiring ,if it heats up much you may have to beef it up. check your switches and overloads to see if they will handle the fla rated on the motor (fla = full load ampperage).
are both motors the same speed, shaft size?
 if you have another smaller motor 5 or 7.5 hp just add it in line after your rpc, or use the 15 you took off the mill, adding more motors in the 3 ph circut helps balance the phases.  you may still want to find a good electrican that can balance the legs on the 20 for the very best performance.

jim 

[scrout]

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