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Thread: Someone experienced in 3ph to single ph conversion ?

  1. #1
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    Someone experienced in 3ph to single ph conversion ?

    Hi,
    The job seems to be not easy and requires someone experienced in 3 phase to single phase conversion for a "medium" sized compressor.
    The HVAC system is a split cooling/heat pump using the compressor described below. The system was bought as 400v 3 phase unit but now, due to local electrical restrictions the house can not be supplied with 3 ph anymore, and therefore, the system must be converted to single phase supply.
    The problem is that the compressor is somewhat bigger than "normal" used in smaller systems using run (and eventually start) capacitors and that is why I prefer to ask for help here: if someone have the value of the capacitors or a clue on how how to get it for the conversion.

    COMPRESSOR: Copeland zr61kc-tfd-522
    R22, power input: 4KW, power output: 14Kw, 50000 BTU/h,
    400v 3ph, Rated Amp: 8, RLA: 10A, MCC: 14A, LRA: 60A

    Thanks in advance for your help,

  2. #2
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    New comp and wiring, that would be the most common way and cheapest.
    UA Local 32 retired as of Jan 2020

  3. #3
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    Thread Starter
    Thanks Buford for your prompt reply.
    Unfortunatelly, just new compressor would cost arround 2.000 USD, what makes it unafordable. That is why I thought on conversion 400v 3ph star to 220 1ph delta with capacitors (conversion using electronic inverter is also an expensive way althoungh cheaper than changing the compressor).
    What I really do not know yet is if the Copeland conections allow the change star-delta...

  4. #4
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    I do not know that, i would keep it simple and change the comp. sorry
    UA Local 32 retired as of Jan 2020

  5. #5
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    You have to change that entire unit, because if you don't the cost would be more than a new unit. And who had their head up their butts thinking a power company allows home owners to have 460 3 phase.
    Federal Reserve, stealing your kids futures since 1913

    UA290

  6. #6
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    Buy a used compressor on eBay. Cheapest way around it.

  7. #7
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    As others have said, it can't be done. Give up on the crazy idea of trying to operate this thing on single phase 230v power. It ain't going to happen.

    Sounds like you found some kind of amazing deal that you couldn't refuse. Time to chalk this one up as a learning experience and cut your losses and start over. Find a reputable HVAC contractor that knows what they're doing and pay them what ever it takes to provide a properly designed and installed system.
    If at First You Don't Succeed, Skydiving Is Not for You.

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  9. #8
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    Quote Originally Posted by buford View Post
    New comp and wiring, that would be the most common way and cheapest.
    Quote Originally Posted by VTP99 View Post
    Buy a used compressor on eBay. Cheapest way around it.
    Quote Originally Posted by HVAC_Marc View Post
    Just change the compressor. It's the least expensive most reliable route
    Don't forget that if you go this route, you will also need to replace the condenser fan motor(s) and anything else that isn't designed to run on 230v single phase (or whatever they've actually got there). Also as buford said, you may also need new wiring since the 230v stuff will draw more amps than the 400v stuff and may require bigger wire. You will also void your UL listing and could be on the hook if your house ever were to burn down. (Never mind the fact that it's a commercial unit in the first place, which could cause insurance type problems on it's own).

    Anyways, Good Luck.
    If at First You Don't Succeed, Skydiving Is Not for You.

  10. #9
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    Just change the compressor. It's the least expensive most reliable route

  11. #10
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    Quote Originally Posted by ammoniadog View Post
    Don't forget that if you go this route, you will also need to replace the condenser fan motor(s) and anything else that isn't designed to run on 230v single phase (or whatever they've actually got there).
    Good point, 208/230 3ph might be more feasable seeing how they (the manufacturers) will use only a single phase for those other motors. But 480 not likely.

  12. #11
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    Just remember, HP is HP and when you decrease the voltage it increases the current, which means bigger wire.
    Federal Reserve, stealing your kids futures since 1913

    UA290

  13. #12
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    I have wired three phase motors to run on single phase, and yes, it is done with capacitors. There is a rule of thumb, but best if you Google it for yourself. But there are a couple problems besides what have already mentioned. First off, to make that existing compressor work, you'd need to first step up the voltage. Then do the special capacitor trick to make it run on single phase.

    Secondly, if only doing the capacitor trick, then you lose horsepower. Can't remember how much, but in this application, you would not have good results. Works good for things like drill presses and lathes.

    If you want to maintain capacity, then after stepping up the supply voltage, you'd need to power another motor with the capacitor trick. It just idles along with no load. Then you tie your existing compressor in parallel with that idler motor.

    So, yes, it can be done. And I have done it. But not to an HVAC compressor.

  14. #13
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    Quote Originally Posted by BBeerme View Post

    So, yes, it can be done. And I have done it. But not to an HVAC compressor.
    And it sounds less reliable than other options, plus more expensive than the 2k he was griping about.

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  16. #14
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    It's kinda fun to do. You feel like you're defeating the laws of electricity.

    In the case of the OP, a whole new system is likely the best option.


    Quote Originally Posted by HVAC_Marc View Post
    And it sounds less reliable than other options, plus more expensive than the 2k he was griping about.

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  18. #15
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    Not to mention how dangerous it would be with a step up transformer and a bunch of capacitors laying outside the unit, hack job.
    Federal Reserve, stealing your kids futures since 1913

    UA290

  19. #16
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    Thanks guys for your advice.
    I found the information of this Copeland compressor and unfortunatelly it is clear that there is no accesible conections with jumpers to make the star to triangle conversion. Therefore, there is no way to use it with 220v, and in consecuence, no matter if there is solution or not for the single phase issue.
    The only way I have found is to use an electronic inverter for about 600 usd (220v single ph to 380v 3 ph 7kw)
    I know that the starting peak of a 4kw compreessor is huge for an electronic inverter, but this compressor is a scroll device with a soft start even with not equalized pressures, so, I hope it can work... żor not?

  20. #17
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    Quote Originally Posted by maximusvigor View Post
    Thanks guys for your advice.
    I found the information of this Copeland compressor and unfortunatelly it is clear that there is no accesible conections with jumpers to make the star to triangle conversion. Therefore, there is no way to use it with 220v, and in consecuence, no matter if there is solution or not for the single phase issue.
    The only way I have found is to use an electronic inverter for about 600 usd (220v single ph to 380v 3 ph 7kw)
    I know that the starting peak of a 4kw compreessor is huge for an electronic inverter, but this compressor is a scroll device with a soft start even with not equalized pressures, so, I hope it can work... żor not?
    Your wasting your time and money.

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  21. #18
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    i bet he doesnt tell us how the inverter melted after a few starts

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  23. #19
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    Quote Originally Posted by BBeerme View Post
    I have wired three phase motors to run on single phase, and yes, it is done with capacitors. There is a rule of thumb, but best if you Google it for yourself. But there are a couple problems besides what have already mentioned. First off, to make that existing compressor work, you'd need to first step up the voltage. Then do the special capacitor trick to make it run on single phase.

    Secondly, if only doing the capacitor trick, then you lose horsepower. Can't remember how much, but in this application, you would not have good results. Works good for things like drill presses and lathes.

    If you want to maintain capacity, then after stepping up the supply voltage, you'd need to power another motor with the capacitor trick. It just idles along with no load. Then you tie your existing compressor in parallel with that idler motor.

    So, yes, it can be done. And I have done it. But not to an HVAC compressor.
    I've got a customer running a 3 phase ice machine compressor on single phase supply. We've got a capacitor bank called roto phase and the idler motor. It works well.

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  25. #20
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    Quote Originally Posted by Red Man View Post
    I've got a customer running a 3 phase ice machine compressor on single phase supply. We've got a capacitor bank called roto phase and the idler motor. It works well.
    I've seen my pops do the same thing. It was on a commercial 3 phase washing machine, for a laundry service.

    Sent using crapatalk.
    "If you can’t describe what you are doing as a process, you don’t know what you are doing." ~ W. Edwards Deming

    All those who wander..are not lost.

    Do NOT..mistake my kindness for weakness.

    The early bird may get the worm..but the second mouse gets the cheese.

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