vintage Century 3.4 hp A.C. motor 120/230v need help converting to 230v

joem64 · Jul 2, 2017

I have an older large Century 3/4 hp (or is it 1-3/4 hp? not sure) mounted on an old Craftsman 18" vert. bandsaw which is currently running on 120v. I'd like to convert it to run on 230v but have not been able to find any info on this motor (pic of data plate below) Also the wiring cover is missing...not sure if it would have had a wiring diagram or not but it's gone anyway. There are 4 wires leaving the motor housing. At the on/off switch (pic attached) there is a white and a black wire attached from motor to switch and a white and black wire that heads out to the wall plug. Tomorrow I will pull the electrical tape off the 4 wire connections at the motor and post a pic of the way things are connected. Does anyone have any thoughts on how I can get this motor to run on 230v?
thanks.

Century alternating current motor motor plate.jpg

bjmh46 · Jul 3, 2017

Hope this works. Good 'ol repulsion/induction century!

joem64 · Jul 3, 2017

bjmh46 said:
Hope this works. Good 'ol repulsion/induction century!

Thanks! It looks like lines 1,2 and 3 are twisted together or is that a rip in the paper label and just 2 and 3 should be joined.
Thinking about it a little deeper based on the thought that 120v pairs of coils are wired in parallel vs 230 coils in series leads me to suspect that only lines 2 and 3 in the pic should be wired together and that the label is ripped??
thanks

joem64 · Jul 3, 2017

joem64 said:
Thanks! It looks like lines 1,2 and 3 are twisted together or is that a rip in the paper label and just 2 and 3 should be joined.
Thinking about it a little deeper based on the thought that 120v pairs of coils are wired in parallel vs 230 coils in series leads me to suspect that only lines 2 and 3 in the pic should be wired together and that the label is ripped??
thanks[/QUOT

EDIT: I think because I used the key word "convert" in the headline my thread got diverted to VFD/roto-phases etc. ??

bjmh46 · Jul 3, 2017

Yes, an unfortunately placed tear in the label! 2&3 are joined.
Line to 1 & 4.
2 & 3 are not joined to 1.

Regards
Bob

joem64 · Jul 3, 2017

Thanks for the help Bob.. hoping to get out to the shop and get it running tonight.

joem64 · Jul 4, 2017

joem64 said:
Thanks for the help Bob.. hoping to get out to the shop and get it running tonight.

update: So as it turns out it was allready wired for 230v. When I tested it on a 120v circuit it seemed to run ok. Now it runs like strong.
How can I confirm that it's running as it should... or why did it run on both 120 and 230 before?

bjmh46 · Jul 5, 2017

Hi Joem64,
Those r/i 66frame motors are noted for extremely high (400% of full load rated) starting torque. They were used a lot in commercial refrigeration equipment. I can see, even at 1/2 voltage (120 supplied, wired for 240) that 3/4 hp motor would have no trouble starting and running that 18 band saw. Probably have to go pretty slow though, to resaw even a 4 or 5 inch board.

Bob

joem64 · Jul 6, 2017

bjmh46 said:
Hi Joem64,
Those r/i 66frame motors are noted for extremely high (400% of full load rated) starting torque. They were used a lot in commercial refrigeration equipment. I can see, even at 1/2 voltage (120 supplied, wired for 240) that 3/4 hp motor would have no trouble starting and running that 18 band saw. Probably have to go pretty slow though, to resaw even a 4 or 5 inch board.

Bob

Interesting that you mentioned refrigeration. The old timer I bought the saw from 25 years ago.. I remember him saying he was retired from a refrigeration factory. (Back in the day when there was things called factories)

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