Running 240 3ph tools in a 208 3ph facility ?
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    Default Running 240 3ph tools in a 208 3ph facility ?

    Hello !

    Considering to relocate our small business to a new facility that has 208 3phase power. Our 2 milling machines (and 3 other tools) run off 240 3ph in our current facility. I know our vintage mill had the motor completely rewound ~4 years ago specifically for 240 3ph.

    I don't think the tools have a simple wiring connection we could swap to make them designated for 208, so I'm curious what kind of transformers, phase converters, etc... people have used to make a tool work on a differ facility voltage ?

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    The first step I would take is to post that very same question in the "transformers, motors, and VFD" subforum of this very site, since it seems more relevant to the topic than a management issue.

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    I run my 240 stuff on 208.

    Most of my welders have a spot for 208 or are multivoltage capable.

    Ironworker and Pressbrake are flywheel driven so the motors have an easy life except for startup, and no real electronics.

    My last cnc mill had lugs (not the correct term) where you could adjust over a certain range for your actual input, so I was fine there.

    My 208 is actually 212+...so you may want to measure (some say +/- 10% is legit....and it is for me on my old stuff.

    Newer stuff and $$$ I'm going to make sure I have an electrician install some buck-boost transformers if it's critical.

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    You sure you don't mean 230V? Didn't think 240 was a thing. Could be wrong.

    My building switched over to 208 and I had the same thoughts and fears. I've been running on 208 and no problems now for over a year. I have all Japanese machines and they're listed at 220 or 230. Sorry can't recall off the top of my head.

    You can get two single phase boost transformers that will boost your 208 up to very close to 230 or better. I think I bought a pair of 5kva transformers that I was going to use for my Mori mill that is wired to a 200 amp breaker. I also have a couple 3kva that I bought to run a 3 phsase 10 hp compressor. Over kill there I think.

    Let me know if you're interested in these as I still have them and would sell for what I bought them for. FYI, I find good things at bargain prices. My shop is full of good things.

    The buck boost literature will help you decide your kva needs. These transformer I have will run some pretty amp hungry machines.

    Dave

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    The OP's 240 volt 3 phase power sounds like BS to me. I cannot imagine it even exists anywhere. How is this voltage measured? I assume it is RMS leg to leg. If so, the individual leg to neutral voltage would have to be around 180 volts and that just doesn't compute. Please educate me if my assumptions are incorrect.

    In north america low voltage 3 phase power is a nominal 208 volt +/- 10%. Anything outside that is a power company problem not yours. Further, all 3 phase equipment will usually run very happily within this 10% limit.

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    Quote Originally Posted by steve-l View Post
    The OP's 240 volt 3 phase power sounds like BS to me.
    Quite possible if running off an unbalanced phase converter in an area where the single phase service runs on the high side. I have seen single phase 220 as high as 247.

    As for the OP's question if those machines are manual they will be just fine as is. If they are CNC I have seen some that have braking units and other settings on components for voltages that ranged from 200-230v. Other CNCs have had no settings to change.

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    I have 240v 3 phase. It is a delta transformer configuration with a center tap between two of the legs to provide 120v single phase.

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    Quote Originally Posted by abollman View Post
    Hello !

    Considering to relocate our small business to a new facility that has 208 3phase power. Our 2 milling machines (and 3 other tools) run off 240 3ph in our current facility. I know our vintage mill had the motor completely rewound ~4 years ago specifically for 240 3ph.

    I don't think the tools have a simple wiring connection we could swap to make them designated for 208, so I'm curious what kind of transformers, phase converters, etc... people have used to make a tool work on a differ facility voltage ?

    Well, I'm gunna say that Jamscal and Dualkit (and Archer) have it covered.
    I'd question the rest.


    But one thing that you ask about, and hasn't been covered (as it doesn't seem to fit the situation) is the question about the phase convertor.

    ???

    208 should be a 3 phase voltage only.

    A phase convertor is going to pull off of single phase, and that would always (?) be 240.
    I doubt that you would find 208 single phase anywhere in the US?

    So - if you have 208, you shouldn't need a phase convertor.
    ???


    230 hasn't been a thing since what - the 70's?


    -------------------

    Think Snow Eh!
    Ox

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    I have 240V 3-phase. As it happens, it is also 208V.

    As Archer said, if you have 240V leg to leg 3 phase with a grounded center tap between two legs, you will have two 120V leg-ground legs, and one 208V leg-ground leg. It is because of that difference that this is called a wild-leg delta configuration. In my building most all the wires are just black, but the wild leg is marked with red tape in each box.

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    I have 240V with a wild leg here...........it's actually closer to 250V when you throw a meter on it...............the Haas machines have multiple taps for various voltages. The 2 Doosans need buck/boost transformers getting the juice down to 220v +/-.

    OP.......any 3ph motor will be fine. The CNC's may need transformers to bump it up a bit.

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    The biggest concern would be what control voltage your control needs. A lot of CNC machines need 24V DC. If your supply power is too high or too low, it will either burn up your boards/drives, or not run them. I would take the time to find what the machine wants in your electrical book, and check to see what you are running now.

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    So basically you're moving from a 240 Delta service to a 208/120 Wye service.
    That's it, nothing else.

    Your plane-jane machines SHOULD be OK with the lower voltages. May run a bit warmer and less efficient, but motors usually can handle voltages
    over/under their normal rating ( assuming they aren't used at or very near full load at all times )

    More sensitive equipment, such as CNC-s usually can handle +/- 10% of deviation.
    Obviously in your case it exceeds that limit.
    Typically tho they will either have a multiple tapped transformer where a 208V tap is absolutely available, or you will need a boost transformer
    to get up-to within that 10% limit.
    Not a real big deal !!!
    In your case 2 pcs of 16/32V secondary transformers connected in "autotransformer" mode can be used.
    All of these transformers come with the wiring diagrams explaining how to connect them into buck/boost mode.
    208V + 32V = 240V

    Ox

    208V single phase is about all you have available in major cities, unless the installation warrants something else.

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    Quote Originally Posted by SeymourDumore View Post

    Ox

    208V single phase is about all you have available in major cities, unless the installation warrants something else.
    I think you meant "208 Wye 3-Phase", as for-damned sure Dominion VA Power has been reliable on 246 VAC single-phase for Donkey's Years, here.

    Powerco's can engineer whatever a customer has involvement of folks with the proper credentials to specify, draw permits for, and get through inspection - but "prefer" Wye distribution over Delta, any flavour, as a "LAST" leg default.

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    Quote Originally Posted by thermite View Post
    I think you meant "208 Wye 3-Phase",
    Bill, Yes, the source is 120/208 3Ph Wye, but often only 2 phase and Neutral is brought into the residential installation.
    Condo complex I've lived in for 15+ years had exactly that, and that is typical for all condominiums in our neck of the woods.


    And I should have said : " in many parts of major cities "

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    Not that it's of any help but, the op is in California, he's should be lucky he has any power at all

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    Quote Originally Posted by SeymourDumore View Post
    Bill, Yes, the source is 120/208 3Ph Wye, but often only 2 phase and Neutral is brought into the residential installation.
    I submit that you mean single-phase or "split phase", centre-tap to Neutral, also Earthed at the entrance (only). That's North American & Japanese practice, mostly. Europe et al work directly off two of the 3-Phase legs @ 230-250 VAC for residences, but do not ordinarily provide 120 VAC service at a wall outlet.

    TWO phase still exists, BTW, but only "barely".

    With need of four, not three power conductors as 3-Phase uses, the Copper cost of two-phase was never as popular with investors and their bean-counters when 3-Phase was both smoother and cheaper to distribute.

    "Really Cheap" is single-phase, one wire, with "phantom" return through the Earth, same as a simplex-phantom [1] telegraph cable.

    Cost issue, again - Andes mountains, mostly.

    "Back in the day" it was seen as better than no electricity at all - and "oh, BTW" could also provide that telegraph, later voice telephone service, later-yet, data - all over that same solitary wire - to a village, police post, border outpost or such.

    An IC engine PLUS its fuel and lube ever-after, far the more enduring challenge - wudda needed packing up the mountain on animal back, be it four-legged "animal" or only TWO!



    [1] Probably MOST of the internet gets the descriptions wrong in co-joining the terms that LONG predate radio.

    "Simplex" is a "one-way" (at time..) circuit. Radio, clear into War Two, Citizens band, aircraft, walkie-talkie.. "over.." ... plus most early submarine telegraph cables were so configured, then operated send-only one way part of the day, laboriously switched-over on rigorous schedule, operated the other direction the other half.

    "Laborious" as some of them needed 8,000 Volts in at the sending end to deliver a gnat's-fart worth of signal to the other end, and at as little as FOUR words per minute, even so, inductances as they were, 1898, completion of the world's first more-or-less "global internet".

    Faster than steamship? Not always. Typical 2-week wait in the queue to get a commercial message to the telegrapher's key. Longer-yet if the priority-holder - the British Government - had a war on or something similar that took up all the bandwidth.


    "Phantom" is just what it sounds like. No visible conductor. Full-duplex phantom has existed, so it is not limited to "simplex."

    The capacitance, not resistance, of the Earth's skin is used as a "sink" to simulate a conductor, given it takes a Hell of a lot longer to "charge" such a lossy capacitor it never much notices that we puny humans are even making the attempt. Earth is a conductor with (usually) high resistance as well, but that is more hazard than help.


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    Quote Originally Posted by thermite View Post
    I submit that you mean single-phase or "split phase", centre-tap to Neutral,

    No, that is absolutely not what I mean at all!

    Quote Originally Posted by thermite View Post
    Europe et al work directly off two of the 3-Phase legs @ 230-250 VAC for residences,
    That is exactly what I mean, and that is how it works here too!
    2 of the 3 phases in the US ( Wye supply) means 120V between L-N and 208V between L-L.

    Condo complex has a large pad ( or underground ) tranny for 10 - 20 - 50 - 100 - 500KVA of 120/208 secondary, all in 3Ph Wye of course.
    Then only 2 of the 3 hot legs, along with the Wye center is brought into the residence.
    120V - L1-N, 120V L2-N, 208V- L1-L2
    Simple like.
    Last edited by SeymourDumore; 10-11-2019 at 04:32 PM.

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    bill you need to find something to do with your life besides type out more creative explanations of the same damn thing each time the subject comes up.

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    Quote Originally Posted by johansen View Post
    bill you need to find something to do with your life besides type out more creative explanations of the same damn thing each time the subject comes up.
    Can I help it I'm congenitally patient?

    We shall just have to keep doing this until you get it right!

    Or they fix the PM search function so folk actually TRY to use it?

    Or - perish the very thought - search the 'net?

    Mains electricity by country - Wikipedia

    Branch-off to "See also", bottom of the page.

    Mind .. I'm limited. Only had to deal with configuring telecoms gear for 62 countries, only personally used appliances and tools in 51 countries..



    Ask the old C&W mate - an Engineer globally recognized for his specific expertise at powering-up the grid of medium islands and small nations, fer crissake - that I have been trying to get to accept that single-phase does not automagically become "two-phase" just because you distribute it off a centre-tapped transformer.

    For thirty years, already. With oscilloscopes, even. It seems to be an "English thing", much as the French refer to "the English disease", apparently.

    Semantics. Some words mean what you say they do NOT mean?

    Mind, I'm limited as to experience. Only had to deal with configuring telecoms and 'puter gear to go into 60 or 62 countries. Only personally set foot in and used 'lectrical stuff meself in 51 countries, only 16 or so w/r FM sites, hands-on.

    So? Just mind what the REAL experts have to contribute and we can both still learn a few more tricks?



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    Quote Originally Posted by SeymourDumore View Post
    No, that is absolutely not what I mean at all!



    That is exactly what I mean, and that is how it works here too!
    2 of the 3 phases in the US ( Wye supply) means 120V between L-N and 208V between L-L.

    Condo complex has a large pad ( or underground ) tranny for 10 - 20 - 50 - 100 - 500KVA of 120/208 secondary, all in 3Ph Wye of course.
    Then only 2 of the 3 hot legs, along with the center tap is brought into the residence.
    120V - L1-N, 120V L2-N, 208V- L1-L2
    Simple like.
    "Simple like" a condo is a legal term to do with ownership, not a technical term, so it is not clear if you are talking a residence, office, or row of industrial spaces?

    A hotel, office building, apartment block or such does not necessarily resemble what is delivered to the legions of smallholders running machine-tools.

    We/they are either in:

    - a subdivide of a "proper" 3-Phase shared-spaces industrial park, not necessarily Wye, even if 3-Phase, and not necessarily 208 even if Wye. My Wye is locally-derived, and 208 to 220 dial-able (gen set) to 240 VAC (RPC or Phase-Perfect -> Delta-Wye transformer).

    Because my (old) motors like it better that way, and I like a local Neutral, all legs the same potential above protective Earth - no wild leg, high-leg, stinger, "lighting circuit tap", nor corner-ground.

    - OR we are struggling with small-shop residential-grade service, stand-alone. Which is 120/240 VAC "split phase", US system, not European one, much as we might wish it wasn't so and didn't need to spend on VFD, RPC, P-P, etc.



    If your shop actually has 208 Wye on the meter? Not all that common, but "run with what yah got". ELSE add boost (auto) transformers if need be, and leave the grid to the utility company.

    Might be cheaper that way. Check the "demand" figure and billing for it.


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