changing a dedicated 460 volt motor to a 230 volt motor

Treelaw45,

Yes, but only if the motor has the proper type of winding. There should be a nameplate on the motor. If it says 230/460 Volts, then this can be done. The wiring connection diagram will be typically on a plate nearby or a label on the inside of the terminal box. If there are only three or six leads in the terminal box, forget it.

I hope you don't have enough experience or knowledge to be dangerous.

--John M.

If your motors are NOT wound for dual voltage, you can just get a 30kVA transformer to feed those 2 motors or one 15kVA for each motor; no need to change everything in your shop!

But you should keep in mind that 2 x 10HP 230V motors is a BIG load for the average residential service especially if, as you indicate, you have other loads. If you plan on using only one machine at a time, as most home shop users do, then just get a single 15kVA transformer with one plug outlet and put a cord on each of those machines with that corresponding male end and only plug one in at a time.

Well, if you've wound motors before you can do it. I surely wouldn't and I've wound motors before. For your information you would have to find the splices that connect the individual coils in series and figure out how to reconfigure them for the voltage. Probably never get it together right again and insulated properly. When they weld copper wire ends of the coils together there is nothing extra left so you would not have any extra wire to mess with. It would be hard to work so close to the coils without damaging them. Find another way if possible to modify the available power, that would be easier, but good luck if you try to modify the windings,

I'd like to hear about it if you do.

Are these 3 phase motors?

Please read the nameplate.

Does it say 460V star or delta?

How many cable leads are brought out to the terminal box of the motor?

If star the cable leads that connect to the electricity supply can be connected to delta thereby converting the 460V to 230V. For connectionsw you can look up the mannual on the motor.

Our experience s for most North American motors this is easily possible.

Eliyas,

Not true on star to delta connection changes. The star voltage is 277V, not 230. Therefore your supply voltage would be about 20% low, which is outside the design range for the motor. Dual voltage motors have two separate sets of windings whose leads are brought out to the terminal box. If connected in parallel then you are on the low voltage and if in series you are on the high voltage. If the motor design is for star connection, then typically only nine leads are brought out (one star is internally connected because it never needs reconnection). If the motor design is for delta connection, then all twelve leads are in the terminal box. This is why my earlier post said that if there were six leads or less in the terminal box, there was no way to reconnect it for the 230V supply.

Be safe--JMM

jmueller; if there are 6 leads brought out of the motor it can be connected star or delta as an example 220 volt 3 phase delta, or 380 volt 3 phase star(wye) , or 240/415 volt or 230 volt/400 volt. perry

There are only 3 leads coming out of the box. I post the original question and from the responses it appears that it would be difficult if not impossible for me to covert this motor. The main reason seemed to be explained to me in one post that the windings connected in series were welded together leaving virtually no extra wire to form new connections so it isn't simplely a matter of opening the back of the motor and reconnecting wires. There also seemed to be an indication of damaging the seals and bearings, the motor does weigh almost 400 lbs. It looks like using a 15 KVA transformer and running just one 10 hp motor as a 460 V rotary phase converter and then rewiring the motors on the machines meant to operate that are labeled 230/460 V is best, or use another transformer after the home made rotary phase converter. If anyone disagrees please explain. There was also concern that the house current would be insufficiant to run the two 10 hp motors as rotary phase converters and to stick with just one, Athough I do have two 100 amp services coming in?

Treelaw45,

You've done a good job in supplying information in response to our posts. Thanks. The main concern when dealing with the larger motors on a service is not in the running of the motors, but in the starting of them. When a motor is getting started, it draws a lot more current than when it is running and doing its normal work. This excess typically is 6-times its running current at first and then drops down as the motor gets up to speed. If your load has little inertia, the motor may get up to speed in a second or less. During this starting time you usually will see lights dim because the large amount of current is causing a greater voltage drop on the lines coming in. Running a 10-Hp or even a 20-Hp motor on 230V is not a problem for a 100-amp service. Starting it may be a problem.

From the information you have posted, I believe you will do OK. When the first motor is started, its rotating inertia can help contribute power back to the line for starting the second motor. A transformer may have to be sized to allow the extra inrush current of starting the motor(s).

Perry is correct in the voltages he names for star vs. delta connections of a 6-lead motor. Note that the ratio between the high and low voltages in his post is 1.73:1, not 2:1 as was earlier suggested by another person.

I believe you have the information you need from us. Take it and use it.

Work safely--JMM