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Thread: RPC question

  1. #1
    Join Date
    Jan 2006
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    Kansas City Mo
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    142

    Default RPC question

    Presently building a 7.5 HP RPC. Right now I have one three phase drill press but will be accessing more 3 phase equipment. To wire several machines to the RPC do I need a sub panel that the individual machines are wired into. Or just how is that done.

    Also the 3 phase drill press has a 1 HP motor, can I just wire the drill press directly to the RPC until I really need the sub panel or junction box. The 220 single phase input is on a 30 amp breaker. The drill press is currently on a small VFD, but with all the new equipment I plan to buy, I invested in the RPC.


    Gear

  2. #2
    Join Date
    Jan 2003
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    On the Oil Coast,USA
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    Default

    Sure you can wire the RPC directly to the DP so long as there is a switch or disconnect between the two.

    Easiest method for adding machines later is to find a small 3~ breaker panel and wire the RPC to it.Then it's just a matter of adding a breaker when you need another circuit.
    I just need one more tool,just one!

  3. #3
    Join Date
    Jan 2006
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    Kansas City Mo
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    Default

    Why the switch between the two (DP and RPC) if the converter is off the drill press is off right. Or I'm missing sometime here. Can't I just use the off/on on the drill press if the converter is running.
    Last edited by gearhead; 05-17-2009 at 05:25 PM.

  4. #4
    Join Date
    Jan 2009
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    Southern WI
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    Default

    The switch between the Drill Press and the RPC is required by Code. My understanding is that as long as you have some way of disconnecting the DP from the RPC, (like a plug and outlet), you are Okay. The RPC qualifies as a power source.

  5. #5
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    Kansas City Mo
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    Default

    Ok got it...thanks for the clean up. Did some surfing for a 3 Phase breaker panel. Pretty expensive stuff. Anyone have a source for one of these in the cheaper range. I don't need a big panel just one big enough for three machines to be attached....gear

  6. #6
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    Ebay,prolly somebody on there has breakers too.

    http://cgi.ebay.com/Square-D-QO312L1...ayphotohosting
    I just need one more tool,just one!

  7. #7
    Join Date
    Jan 2004
    Location
    Missouri
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    Default

    There is no real reason you HAVE to have a panel....... in the US at least.

    So long as the output wires are properly protected, each machine has protection, and some acceptable disconnect means is provided for each, you could treat the RPC output as a single branch circuit.

    IF the machine is rated above a certain current, which IIRC is 50A, then you need a dedicated branch circuit for each such machine. But below that number, you can have a multi-outlet circuit right off the RPC.

    Why would a panel be required?

  8. #8

    Default Good source for 3PH panel

    Get frendly with your local junk yard! (I'm surprised that someone else has not already mentioned this!)

    Since scrounging seems to be a necessary trait of good machinists in this area, often times the local junk yard is the best source for some things very useful!

    I'm fortunate to be in a rural area and have a friendly junk/salvage yard operator. He allows me to check out his stuff, and since he sells stuff to steel mills for the going price per pound, I ususlly get the things I can use for that same going price.

    One practice I use, and consider a cardinal rule! [B][U]Don't haggle the price!
    Knowing what the item is worth, if you were to buy it from another source is important in knowing just how good a deal you are getting.

    Another practice that I think is helpful, after I finish a project, I take pictures, and show the salvage dealer how I used the stuff he sold me!

    A natural scrounger, Doc-Zeus

  9. #9
    Join Date
    Jan 2006
    Location
    Kansas City Mo
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    Default

    Very good information here. Right now I just have the one 3 phase machine. Can I just put on a female 3 phase plug on RPC 3 phase out end and then plug in the different machines as I get them. I know this is not very progressive thinking but until I come up with something else is this idea still good. Or is there other issues on this....gear

  10. #10
    Join Date
    May 2008
    Posts
    121

    Default

    I have a "remote switch" for my RPC that is right over the outlet (RPC is in a space on the other side of the wall). If/when I need a second 3PH circuit I plan to add a second outlet. Along with the switches on the machine(s) themselves I don't see the need for anything fancier.

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