AboutWill Expertise Three phase electic motors, controls and related problems or failures, three phase motor installation issues, performance issues, connections, data and duty cycle information. All other electic motors. Specialty motors, repair concerns, performance concerns, obsolete motors and solutions. Other specialty equipment issues. Lost nameplate data and identification, lost connection data.
Also DC motors of all types.
See my profile under Home/electrical at this site
Experience 30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.
Organizations EASA, IBEW [retired], other specialty organizatons, Lubrication, Vibration EDI, Triboelectric Councils
Publications Currently fielding concerns at this site under "Home Electrical"
Education/Credentials 4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.
Expert: Will Date: 5/9/2008 Subject: 440V to 220V Three Phase
Question Will, I have an old lathe that has a 10HP 3 Phase motor. The brand on the motor is Sterling and it is a two speed. It has low, high, and stop buttons on the switch. It has three black wires and three red wires coming out of the motor. My question is that the name plate says 440V, how do I change it to 220V so it will run off of my phase convertor? Thanks Dean
Answer Dean,
You cannot change the voltage to 220 externally. The three red are one speed and the three black the other, separate windings most likely.
To change to 220 volts a motor guy will have to connect the motor windings internally parallel, on both windings. They are most likely a single simple wye or delta and probably can be reconnected without a lot of fuss, it will depend on the existing internal connection.
Long long story, but a motor can be 20 volt and a parallel connection or a series connection, and there all kinds of speed relationship rules that must be followed.
So if you have a decent motor shop near you, they could connect the motor internally to 220 volt, if they balk, move on.
It is possible that the windings are already paralleled, but not likely.
If they are paralleled to the most allowable, then a rewind is the only solution.
Now for some practical issues:
10HP what service and where is the lathe going? A standard household 220 circuit will not stand 10HP worth of current.
If you have a large enough service, find the nameplate amps for the 440, and double it, that will be what you will need for 220 current draw.
Next you have a converter that takes single to three phase, the lathe has two speeds, a frequency converter and single to three phase drive would be ideal.
You could take either the high speed and slow it down, or the low speed and up it, depending on what you are doing in the lathe.
My concern is that if you have a single to three phase converter, is there enough service wherever this lathe is installed to handle the current, make sure of that first.
Now here is another possible answer, if the lathe is geared in such a manner and your load or use on the lathe is light, you might get by, putting 220 to a 440 volt motor, it all depends.
It may fall flat, stall, no torque, or it may have enough to get by, trying it costs nothing, but you need a way to measure running current.
Next is to put a smaller motor on the lathe... a single speed with a frequency converter, there is just a ton of things to consider, and there is no simple fix, other than having the motor reconnected to 220 and there is enough service to handle TWICE THE CURRENT SHOWN ON THE 440 NAMEPLATE as it sits right now.
You are going to have more questions I can tell already, so feel free to write me at service@emrrepair.com
That way we can email directly and go over options as you tell me more about the setup, feed size, usage all that.
