# 3 phase 440v 3hp 50 hertz motor question



## Bishop (Feb 16, 2015)

I have posted this on other forums as well but the more information I can gleam the better, I'm an electrical noob of the tenth degree

I have been patiently waiting to buy a RPC to drive a 3 phase 440v lathe. It's a 1986 Smart & Brown 1024 VSL. There are a number of personal issues I have been dealing with for the past coupke of years that has kept me from getting serious about getting this lathe up and running. I won't bore you with all the details but suffice it to say those issues have resolved themselves. It occurred to me that I might be able to rewire the motor to run on 220v 3 phase and then use a VFD instead of the RPC and step up transformer I was planning on. So tonight I took the backplate of the lathe and got a couple photos. The motor was built by Brooks and Compton but of course I can't find any information on the Internet regarding this particular serial number. It's a 3hp motor and from what I can tell from the website Brooks & Compton the motor might be dual voltage rated? I am also of the understanding that I "should" be able to run a 50 hertz motor on 60 hertz with no real issues?

I'm going to contact the manufacturer and see what information I can get but was hoping some of you might give me your thoughts on my plan. 

Here are a couple of photos.


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## hermetic (Feb 17, 2015)

I don't think you can with that motor, it is rated at 380-420 volts, which is the nominal voltage found all over europe for normal  3 phase. If however it is a brook crompton motor, you need to see how many wires come out of the motor, if there are six, and they are labeled A1 B1 C1. A2 B2 C2 , if you connect A1 to B2, B1 to C2 and C1 to A2, and put one phase of the supply to each junction it is wired as delta, and should run on 240v. The other alternative is to buy a 415v output VFD or look for another motor.
Phil


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## Micke S (Feb 24, 2015)

If the 380-420 motor is Star-wired, which I guess it is, it can be Delta-wired and powered by 230 V plus minus 10 volt or so.

60 Hz will work fine. The rpm will increase with 20% vs. 50 Hz and the power will be the same. But the torque will go down by 20% if the voltage is not increased accordingly.


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## UncleRuss (Mar 2, 2015)

These boys are right on track.  Reconnect as recommended and get a VFD.  After all how does the VFD work?  By changing the cycles.......


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