• Hi Guys,

      I finally found a used 1999 era Yaskawa Motoman UP6 robot arm with XRC controller and I need help with powering it... I bought the robot from a surplus site and don't know if it works, or how much it would cost to get it working, so I don't want to go nuts on expensive solutions at this time.

      I have single phase residential 220/240V power and I'm considering a Rotary Phase Converter (RPC) to create 3 phase power for the robot.

      I've been on the phone with a few manufacturers of RPC's and I would like to get some input on what they are telling me...

      My UP6 robot has a payload of 6KG and uses 3 phase 220V power. kVA rating is 1.5kVA, and Horsepower is supposed to be about 1.5 as well.

      I am proceeding with the knowledge that the voltage requirements are critical, and there can't be any voltage fluctuations more than about 4%.

      Looking over the websites for RPC manufacturers, the common thought is to DOUBLE the Horsepower needed to find the right size RPC.

      So if I conservatively rate my robot at 2HP, I would need 4HP. I have priced a few RPC's from American Rotary and North American Rotary, and they both have 5HP converters that seem like they would be a good fit. But when I called these companies, they immediately tried to up-sell me on more expensive RPC's: Either 10HP models or Extreme-Duty models which are about double the price.

      Can anyone tell me what I should be looking for? Is it the size of the Idler Motor/Generator or the Circuitry /Capacitors/Relays etc. that will determine if the unit will power the robot without any faults or damage?

      Is there some way to tell the Peak current that the robot could draw - and how this affects the stability of the 3 phase converter?

      Many Thanks,


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  • Hi Robodoc,

    Long time! Thanks for answering.

    We’ll, I’m not even going to think about getting 3 phase power run to my house, so for me it’s one of the 1to 3 phase converters. I’ll have to do the best I can… What’s puzzling is that I’ve gotten responses from some people who have told me they use a Rotary Phase Converter and have been having no problems. I’ve been trying to learn what exactly causes problems - so I can avoid them. I know a VFD causes problems because it chops the sine wave, but I thought RPC’s were cleaner, especially if they were tuned with capacitors…

    Any thoughts?



  • Were the welders run off of the rotary phase converters also?

    hmm I am trying to remember is the power supply was run off of it as well. They were auto axcess 300. The controllers were dx100m and MH5. Somewhere I have a picture of the phase convertor. The handling systems were all FS100 which is single phase.

  • hi dekatronic I have the same concerns. I also have a UP6 with a XRC controller.

    i was successful in running the robot on a home made RPC. BUT I became concerned about my electrical setup not being to spec on the voltage to ground , and also i had a pretty wide voltage value from my home made RPC, that is over 15 years old and was just a few inches above the high water line of a salt water flood back in 2017, which destroyed my whole shop. but that is another story,

    The UP6 is just a baby when it comes to power. My RPC is made from a 3hp 3phase motor. It ran my 2hp mill with no problems for years and years.

    But the robot wants a bit cleaner power i guess. And the voltage from my rpc is pretty up and down on the phase to phase.

    In your first post you indicated you were looking for +/- 4% on your voltage I think that is a bit over conservative from my reading of the manuals. please see attached XRC voltage requirements

    most recently i hooked up my VFD to the disconnect box on the xrc to see what it would show. and i still have my same problem of voltage on the ground terminals, but very nice stable phase to phase voltages. This was just for test. i did not energize the circuit. But i do want to know why a vfd won't work a robot?????

    OH and another thing from your PM. my robot was also set up for 480v. If yours is like mine there is a pretty massive transformer in the bottom of the XRC cabinet, that is set up for multi voltage users so to speak. My understanding is that the robot actually wants to see 240vac 3phase, +10%, -15%.

    I am even a bit skeptical about that. If you really go into its guts i am thinking that the individual servo drives/power supplies probably only need single phase, But i have not got that far into it, and don't plan on digging.

    I thought that i was getting a voltage drop thru the transformer, SO i took it completely out of the circuit, and ran straight from my rpc, NO change. and i did not put the transformer back in the circuit.

    So if i cant run on a VFD, I either need a new RPC, And since some folks don't even like RPC for robots, I am looking for a very small 3 phase generator/ alternator . A 2 bearing head that can be belt driven from a single phase motor, Then i can have " real 3 phase power"

  • Based on that logic, you just need 220Vac to power the CPS and a 300 Vdc power supply of the correct amperage and viola.

    I know a thing or two, because I’ve seen a thing or two. Don't even ask about a third thing. I won't know it.

  • i am not really sure about that. i did see a board that might have 3 phase going into it . i will try and see if i can get some readings on it while it is de-energized.

    but until i am certain about this my robot is going to remain unpowered.

    i looked at some rotary converters today, there is a sale on American Rotary converters on ebay. I am going to try and talk to them tomorrow on my drive to work.

    I also found a nice 8kw belt drive 3phase alternator head, the cost is triple from a 5kw rpc but almost double the capacity as well.

  • i am not clear on how the normal power is supposed to work on this switch/ system.

    i understand the L1 to L2, and L3 voltages. but i don't understand how 2 of the legs can have voltage to ground or neutral, and the 3 rd leg can have zero volts to neutral

  • Hi dieselxj,

    Sorry for the delayed response… I thought the thread was dead when responses stopped coming in!

    What did you think about American Rotary? They seemed legit, but I personally didn’t like the different answers they gave me, depending on who it was… You would think they would agree on which RPC would work well - and which wouldn’t.

    I’ve heard from a few people that said they used an RPC and were able to power up the system - and according to them, it worked! But there are other people that warn of DIRE CONSEQUENCES, which makes me hesitant to try.

    I’d love to hear of any progress you are able to make.



  • Hey dieselxj,

    Don’t know if you got my last response…

    Did you learn anything conclusive about the American Rotary converters?

    Just wondered if you managed to make any more progress…



  • i am not clear on how the normal power is supposed to work on this switch/ system.

    i understand the L1 to L2, and L3 voltages. but i don't understand how 2 of the legs can have voltage to ground or neutral, and the 3 rd leg can have zero volts to neutral

    I'm looking at the same issue, hoping to get a robot running with 240V Single Phase. Here's a good explanation of how the L1, L2 and L3 can have no neutral return. -I think that's what you mean?

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    Hope there's good news somewhere on this site...

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