Rotary phase converter balancing

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Moldmaker74

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I have a Arco Roto-Phase converter. It is a model PKO,40HP standard duty unit. I am trying to run a cnc milling machine with a 10HP spindle. I know I should have bought a balanced CNC grade unit.. but this one was a good price on ebay. I need to get the legs more balanced to run my machine. Currently ground to T1 120V, T2 120V, T3 230V(manufactured leg). The unit has all run capacitors between L2 & L3. From what I have read, I need less caps on 2 & 3 to decrease the voltage and possibly add some on T1 & T3.
I have contacted the manufacturer and he doesn't give me direct answers. He has stated "The PKO has an extra bank of capacitors that are normally used when operating as the PKO, but for what you are attempting you will not want to hook these capacitors up." after asking about transfering capacitors he said "You are heading in the correct direction of adding some capacitors to T1 & T2, but you will be limited on how much you can add and how large of a spindle motor you will be able to operate."
Does anyone have experience making or balancing converters? I have read several sites about how to make a converter, but nothing specific to my aplication. I would die to have a schematic for a 40hp balanced unit.
 
Re: Rotary phase converter balancing

Do you use 120 or 240V out of the converter? The line to ground voltages may not matter if the line to line is good. What does it cause your machine to do?

Jim
 
Re: Rotary phase converter balancing

My machine Requires 240V. It boots up, but as soon as I try to start the spindle or jog an axis I get a servo error message or a emergency stop error message.
I just recieved a updated email from the manufacturer "converter has 1,000 mfd tied between T2 & T3. This is what I would try as a first attempt. Leave only 400 mfd between T2 & T3 and put 200 mfd between T1 & T3."
I am going to try this tonight and see what happens. worst case I think is that the idler motor may not start. I will post my results.
 
Re: Rotary phase converter balancing

Have you tried switching the high leg to another phase in the disconnect. We used a phase converter for a water purification system and had to be careful not to put the high leg on the leg that was for the controls. If the motor ran in reverse we simply swapped the 2- 120v legs.

??????
 
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