Motor question, Old Frequency Converter

[RDay]

Hey All,

Ok. We got a copy of the original connection diagram for this system and wired it up. According to the connection diagram:
The 10 HP 1200 RPM motor is the drive for the 15 KW motor Generator.
When the system is in LOW the four motors on the machine are connected to the 230 volt 3 phase line voltage. In HIGH mode the four motors are connected to the output from Generator. We test ran the system and to no one got maimed, killed, or electrocuted when we fired it up. So it all seems to work OK. Thanks to all for your help and info.
Robert

 

[DickDV]

Rday, glad to hear it's in working order.

My curiousity is eating me up tho. If, as you state, the slow speed configuration has the four machine motors across a 230VAC 60Hz supply, then it follows that it will take more than 60Hz to acheive a higher speed.

It seems to me, then, that the alternator driven by the 25hp motor must produce a higher frequency than 60Hz and probably a higher voltage as well, assuming the machine motors are expected to maintain their full torque in the high speed mode.

It appears from the earlier motor nameplate data that the 25hp motor is six pole giving it a full load shaft speed of 1150rpm. The alternator being shaft coupled to the 25hp motor would have to have more than six poles to produce more than 60Hz but that is not apparent from the nameplate given.

Hmmmm! Curiouser and curiouser! Never seen anything remotely like this before!