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  1. #21
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    I called and spoke with the power company today. He said they turn the power up 10V to 250V in June for irrigation and back down to 240V in September.. and that in fact tomorrow it will be going down to 240V.

    Concerning the high leg to ground I was told as long as voltages across all three legs were balanced it should be good. It is still concerning though. I plan to connect transformer first and check how close to 200V output the three legs (U, V, W) are.

  2. #22
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    Toolcat,
    Be careful, if your machine is set up for Wye and you hook Delta power up to it you will likely damage something!
    Wye configuration has three balanced legs, meaning there is no high leg as there is in the Delta configuration.
    Take a picture of the transformer or machine label and post it so others may be able help get the problem solved before any damage is done.
    Goog luck.
    Kevin.

  3. #23
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    I've been reading the net more (dangerous). Called Makino trying to get a manual. I don't know if it will work with delta or only Wye..

    The legs are balanced across each other but not from legs to ground. They are like this image but with only one ground/neural line.

  4. #24
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    From phaseconverterinfo.com http://phaseconverterinfo.com/phasec..._isolation.htm
    "If the three-phase equipment has 120V phase-to-neutral circuits that cannot be isolated and connected to either leg 1 or leg 2, the output of the phase converter must be passed through a 240V delta to 120/208V wye isolation transformer. This transformer will establish ground and neutral at equal distance from all three legs and deliver the power in a wye configuration.
    This is especially important when operating some newer CNC machines that have certain Fanuc or Siemens controls. These controls handle regenerative power from the spindle motor by putting the regenerative power back onto the line utilizing a phase-to-neutral connection on all three legs. If these machines are powered by a phase converter with delta configured power, the regen circuit on the leg manufactured by the phase converter will operate at a voltage that is too high. An isolation transformer must be used to convert the power from delta to wye configuration."

    Here is the transformer plate...


  5. #25
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    Can't remember how the RMC is configured but on the KE, the main input is wired to the main on/off rotary switch. From there the 230 volt (or 480 volt if that is what you have) wires go to the transformer, voltage is lowered to 200 volts and the the 200 volts wires come back to the control box where they supply voltage to run the machine (and are lowered more still for motor contractors, etc)

    I mention this only because it's curious your R,S,T and G wires are cut on the transformer itself as on a KE there is no senario where that would be necessary. But maybe on an RMC your main input goes first to the transformer and then to the rotary on/off switch ?

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    The R, S, T and G wires were cut by the electrician at the school when they disconnected the incoming power line. This is where they had the power coming in. Wire cutters were used instead of a screw driver.

  7. #27
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    Quote Originally Posted by ToolCat View Post
    The R, S, T and G wires were cut by the electrician at the school when they disconnected the incoming power line. This is where they had the power coming in. Wire cutters were used instead of a screw driver.
    In that case, if you are absolutely sure main input first goes to transformer I don't see how it could hurt anything if you connect your 3 phase wires to R,S,T and G..... with main on/off switch in "off" position and then measure the voltages across the 3 input terminals of the main switch before turning it on. As long as you measure more than 185 and less than 215 volts it will be fine. I suspect the "wild leg" won't matter as the transformer should moderate it. But if still worried about it, perhaps post this in the PM transformer, phase converter forum and ask there.

    My shop is 480 volts true 3 phase so my memory is a bit dim on the "wild leg" issues I too recall facing.

  8. #28
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    "High leg delta" is real three phase, its just balanced around a different point. When connected to a delta load, no one will know the difference. You do not want to connect it to a wye load. If the transformer is delta-wye, you don't need to worry about which is the high leg, on the load side it will look ok. But the placard seems to show a wye-wye transformer - if that is what you have, I believe you will definitely have problems with your 240V high leg delta supply. It will produce a high leg on the secondary and may overheat the high leg primary winding. I would not power up until you are sure what you have. It may be very wise to disconnect the machine completely from the transformer output, power up the transformer when you think you have it right, and measure the output before proceeding further. I would do that even if qualified electricians were involved.

  9. #29
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    Thank you again for the help. I believe I am in the market for an isolation transformer to turn the delta into wye. I have a yam cnc lathe to wire up too and it is not worth the risk to burn it or the mill up. Any recommendations on brand/model for the isolation transformer? The rotary phase converter is 30hp.
    Last edited by ToolCat; 09-13-2012 at 02:56 PM.

  10. #30
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    Does that YAM also run at 200V? If they are different, you will need a transformer for each. There are many, many brands, for the most part they all do the same thing. A used one on eBay will cost you about 1/2 what a new one runs. Search for "240 200 transformer" or similar to sort out some of them - there are tons. Most machine isolation transformers seem to be delta-wye. The wye-wye is a little unusual. Check the KVA rating, you want something with enough capacity but not too much (the idle power will increase).

  11. #31
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    It may be very wise to disconnect the machine completely from the transformer output, power up the transformer when you think you have it right, and measure the output before proceeding further. I would do that even if qualified electricians were involved.
    That's what I meant by having the main on/off switch in "off" position. Just connect the transformer to your power and measure the voltage at the input side of of main on/off with main in "off" position. I suspect voltages will be fine (unless the machine was previously run off 480 volts) in which case you can turn it "on" and start 'er up.

    Milacron

  12. #32
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    Quote Originally Posted by Admin5 View Post
    That's what I meant by having the main on/off switch in "off" position. Just connect the transformer to your power and measure the voltage at the input side of of main on/off with main in "off" position. I suspect voltages will be fine (unless the machine was previously run off 480 volts) in which case you can turn it "on" and start 'er up.

    Milacron

    Yup, I'll disconnect the transformer outputs to isolate the transformer from everything and see what the outputs read.

    In the mean time I'm still trying to find manuals. I spoke with makino and the price for each individual manual is $330. I already have the Parts manual, Machine diagnostic, and electrical drawings. I am looking for the maintenance and owners manuals, although I'm not that desperate (yet) to spend $660 for them.

  13. #33
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    Good news. The high leg is gone through the transformer.

    Ground to W, V and U range from 125.7V to 128V

    Connecting between W, V and U range from 217.3V to 221.8V
    I then turned on a 7.5 HP motor on the shaper and again checked between W, V and U. They were within one of 214V

  14. #34
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    Quote Originally Posted by ToolCat View Post
    Good news. The high leg is gone through the transformer.
    Connecting between W, V and U range from 217.3V to 221.8V
    As I said earlier, the transformer will tend to moderate any high leg. Your voltage readings are a bit of a cringer as they are probably ok but not for sure. Normal tolerance is +- 10%, so in theory upper limit is 220 volts. I would say 98% chance it's ok to run the machine as it is now but would still be good to figure out a way to lower the voltage some eventually...either by bypassing your built in transformer or using yet another transformer. If using two sounds strange I do it all the time... I lower 480 volts to 212 volts with one transformer and then raise 212 to 380 volts with another one (for my Euro machines)

    And if curious why 212... it's so I can run 230 volt machines ok but also 200 volt Japanese Fanuc machines without yet another transformer....a useful compromise of voltages in my case.

  15. #35
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    I tried running the machine. I am getting servo alarm errors and all three axises. I didn't write them all down but the X axis alarm error number was 414.

  16. #36
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    Quote Originally Posted by ToolCat View Post
    I tried running the machine. I am getting servo alarm errors and all three axises. I didn't write them all down but the X axis alarm error number was 414.
    Well, if it ran perfectly before you bought it, it's almost certainly something simple... either a board came loose or moved during shipping...or it's your phase converter. Seems like every CNC machine I've ever sold that ran perfectly when it left here but not so when the user got it was due to phase converter use. Only cure was a Phase Perfect. However the phase converter problems are usually more subtle issues. In your case, the issues are more stark and broad based....so I'll bet it's just a tripped circuit breaker or loose board at best...or pinched wire at worse. Could also be lost parameters...you sure your new batteries didn't come loose ?

  17. #37
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    I'm reading that servo errors can be caused by high voltage. I wonder if the next step is buck boost transformer to get the voltage down by 10 or 15V and see what that does.

    PS.. I think my batteries stayed in place, but how can I tell? Can I get past the errors to check if the parameters are still there?

  18. #38
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    Quote Originally Posted by ToolCat View Post
    I'm reading that servo errors can be caused by high voltage. I wonder if the next step is buck boost transformer to get the voltage down by 10 or 15V and see what that does.

    PS.. I think my batteries stayed in place, but how can I tell? Can I get past the errors to check if the parameters are still there?
    Re high voltage...I suppose that's possible but seems unlikely in your case as your voltages are so close to optimal. You can check control to see if parameters still in place even with errors...and/or you could put a meter on the two wires coming from the battery box to see if you have at least 4.7 volts dc.

  19. #39
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    I turned on the 2hp motor on the bridgeport and that lowered the voltage of W, V and U to 216V and then powered up. It booted up with no servo errors. I then did nothing but shut it down and rebooted again and the errors are back. Tried three more times and no good.. errors each time.


    Update... Okay after it has been setting for 15 minutes I tried to power it up again and this time no errors.
    Last edited by ToolCat; 09-14-2012 at 06:36 PM.

  20. #40
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    An RPC doesn't transmit the same current under load on the generated leg, as does the straight utility power. Which in my opinion makes an RPC suitable for powering a motor but not a servo amplifier. That's just me, I'm sure there are thousands of people running CNC/servo machines off RPCs but I think its sort of akin to playing with fire.


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