208 WYE Electric Service is it possible to chang taps to get 480 WYE?
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  1. #1
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    Default 208 WYE Electric Service is it possible to chang taps to get 480 WYE?

    I'm looking at a bigger building that has 400 Amps of 208V WYE. Is it possible to upgrade to 400 Amps of 480V WYE by having Comed come out and change the taps on there transformer. I would also need a different breaker panel inside for 480V and a transformer to supply the original panel with 208V.

    Btw, I already have 400 Amps of 480 at my current location.

    I have a few pieces of equipment that would be a pita or impossible to change to 208V.

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    I have no idea if the power company can change taps from 208 wye to 480 wye? They may have to change the transformers themselves??

    All standard CNC's can run directly on the 208V wye without isolation or step-down transformers, as the control electronics, drives, etc. are designed to run at 200V.

    Then, for your true 480V equipment, you run transformer(s) at each machine to get eh 208 up to 480.

    Might be simpler/cheaper than power company if they charge to change main transformers on the pole?

    ToolCat

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    I'm with Toolcat on this..

    Better off to run a few step up transformers for the few things that NEED 480v, and then
    leave everything else alone.

    I also believe they would have to bring in new transformers... Then you would have to bring
    in step down transformers to drop the voltage down for everything else that you need to do..

    Seems like triple the cost and quadruple the BS to go that route.

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    For Ed to stick with what he has - he would have 1/2 the juice that he has in his current shop.

    I would highly expect the hydro to have to install new (differn't) transformers as you are expecting 2wice as many KVA as the current set-up allows.


    Over half of my CNC's require 480.


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    Might be worth seeing if they can just add 100 or 200 amps of 480. I have 600 amps of 208 and 100 amps of 480 in my shop.

    The 480 is just for machines, so it doesn't have it's own panel. Just feeds a couple disconnects straight off the meter, one of them has a step down xformer for my VF2, and the other is just a 480V SO cord to my saws.

    All my 120 comes off the 208 side along with the rest of my machines.

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    Are we talking 15HP manual machines here or are we talking 75 HP spindle CNC lathes?

    One is no issue to do with a transformer, but the other not so much.

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    I'm not sure what a "standard" machine is, my German spec CNCs require 400v.

    Whether the power company can get you 480v by just changing a transformer depends on what the service in the area is like - I had a serious rework done to power on my building just before I moved in, and was told that 480v was not available, period. (Transformer is shared with neigbhoring property, that may have been part of it.)

    I was however able to upgrade power, and the peak of the value/cost was at 1,200amps 208v - so that's what the building has.

    In short - it may be easier to get way more amps than it is to get higher volts - and so you end up with transformers (like a lot of us use.)

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    Very much doubt the local authority would allow that without replacement of the service equipment inside the building. Unless your service entrance is already rated 480V, you are most likely looking at a pretty substantial $$ outlay to upgrade stuff independent of the power company charges. Never hurts to ask, but 400A 480 volt service equipment is not cheap. Out here, 480 volt service requires ground fault protection on the service conductors, which are not inexpensive. Good luck!

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    Ed

    You say you've got 480V now... Does that mean your equipment is also predominantly 480V?

    For the record, if you need 480 for more than a onesie-twosie, you typically WANT TO pull in a 480V mains, and have a separate 120/208 tranny inside.
    Certainly not the other way around.

    As for switching the mains transformer from 120/208 to 277/480, it depends on the transformer but I believe they typically are not available as such as that would be a waste.

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    The building is fed underground. There is a very large pad transformer outside the building. The transformer is a few feet away from the meter panel, which is already the ct cabinet style. If the transformer just needed the taps changed, the underground wires to the meter panel wouldn't need to be changed. I would have to install a new breaker panel inside the shop, and then a 208v transformer feeding the current breaker panel. I would have twice the power, equal to what I have now, and a separate 480v breaker panel to run the machines.

    I have 2 okuma's that draw 60A 480V, 4 okumas that draw 50A 480V, and a brother that's about 20A 480V. All the machines have transformers.

    I have a bunch of manual machines that all run off a separate 240V service.

    I also have two schunk magnets that run off 480v single phase, and a parts washer with 480v heating elements. These are the problem childs that would need a 208 to 480v transformer.

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    Is your panel inside the building 250V rated, or 600?
    (I can't imagine ever installing new commercial that isn't rated 600!)

    If it is 600 V rated, you should be able to simply re-tap, or change the X outside and then hang a new panel for your 240.

    The current underground warrs are rated for the 400A. They don't care if it is 120 or 600V.


    Would you drop to 208 instead of 240 on porpoise?


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    From what Ive been getting quoted , the transformers at the pole are the cheap part of the equation. To change out the transformers that are currently 200 amps of 208 3 ph, to 400 amps of 480 is around 3400. The panels, breakers,transformers, permits, labor etc to change it all out is looking like 5 times that much.

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    Ed

    It sounds like you do not have any other option but to re-tap ( again, I don't know if that is possible ) or replace the mains transformer for a 480V.
    If you add up your consumers ( machines @ 480V ) you will not have enough power from the current transformer @ 208V.

    About the only thing in the middle is the possibility to change the secondary wiring on the current transformer to be a 240V delta which will gain you perhaps 15% more, but that's it.

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    It's not a for sure thing yet, so I don't have access to the panel unless I make an appointment. But it doesn't look like the panel inside is rated for 600v, and it's filled with a ton of single phase circuts for the building. I would probably just make it the subpanel fed from 480.

    I think I would drop to 208 wye for the manual machines. It's a little over and measures 215v, so I think it would be fine for them.

    I'd also run a couple of the smaller cnc machines that didn't come with a transformer off 208v. Right now they each have there own small transformer sitting next to them. It would be nice to only have one large 208v transformer for the whole building and those machines.

    Quote Originally Posted by Ox View Post
    Is your panel inside the building 250V rated, or 600?
    (I can't imagine ever installing new commercial that isn't rated 600!)

    If it is 600 V rated, you should be able to simply re-tap, or change the X outside and then hang a new panel for your 240.

    The current underground warrs are rated for the 400A. They don't care if it is 120 or 600V.


    Would you drop to 208 instead of 240 on porpoise?


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    Quote Originally Posted by SeymourDumore View Post
    Ed

    It sounds like you do not have any other option but to re-tap ( again, I don't know if that is possible ) or replace the mains transformer for a 480V.
    If you add up your consumers ( machines @ 480V ) you will not have enough power from the current transformer @ 208V.

    About the only thing in the middle is the possibility to change the secondary wiring on the current transformer to be a 240V delta which will gain you perhaps 15% more, but that's it.
    I had the 480v service added to my existing building so it's not a huge problem. I'm still crossing my fingers that the transformer can be retapped. I'd like to upgrade the electrical before I move in, if the deal goes through.

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    Ed

    Not to pry, but do you intend to purchase this building or is it a rental?

    If a rental, I'd plunk down only as much as I'd need to get by, but if for purchase, then sit down and figure out what equipment you have, what they need and what makes the most sense.

    You say that most of them have a transformer, and I'm guessing they are external.
    If so, then find what is the most common voltage that they can live off of ( quite possibly 240 ) and select that as your main supply, ditch the transformers.
    Don't sweat the 120/208 stuff, those transformers area dime a dozen, and having a separate panel for each is not a big deal.

    In my case I was lucky and the building came with a "puny" 1200A of 240 delta service supplying a Minimill size distribution panel with 12 mains breakers up-to 400A/ea.

    Right after purchase, the first thing was to install subpanels in strategic locations ( had none before) for the 240V, and made a couple runs of 2" EMT and 12" distribution boxes
    for the 120V service down the length of the shop.
    Sure as hell nice to have 6 individual subpanels for 240V throughout the shop, cuts down on bus-bars or long runs of #4 or #6 wiring for sure, while the 120 stuff is either double duplexes
    on the wall or bus drops in the middle.

    Believe me, it's a shit ton easier to do it when the place is empty.

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    I would be buying the building.

    5 of my Okumas have internal transformers. Which I like because they are after the disconnect switch on the machines. My okuma genos lathe has an external transformer, as well as my Toyokoki press brake and Brother R450X1. But all three are JIS 200V, so they would run fine off 208 without a transformer.

    The shop in the new building is not air conditioned, but the offices are. The shop will be air conditioned, hopefully sooner than later, so I have to allow for that load as well.

    My current situation is two industrial condo units next to each other. Each came with a 200A 240V single phase service. I added a 200A 240V open delta three phase service when I moved into the first condo unit. A few years after I expanded into the second condo unit I added 400A of 480V. So I actually have quite a bit of power coming into the buildings.

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    Edster, you seam to be missing this, if you retap a transformer delivering 400amps at 200 what ever volts, to 400 what ever volts, you half your current availability down to 200amps. Yes the wiring if suitably rated for the voltage is fine, but a transformer can only transform so much energy - its KVA rateings, its your choice weather you have that as more voltage or more current, but you don't get both.

    IMHO though your missing a far bigger issue, transformers are only so efficient. You don't want to be running everything off transformers, especially if you want to AC your space. The idle heat loss of that much transformation is lost then your paying more to remove that heat.

    The magnets should be easy to power with a transformer simply running backwards, its done the world over every day and transformers don't care less which way they have the power pass through them.

    The parts washer, me i would just run at the reduced voltage, yeah it half's the heating power, but it may prove to be enough, if its not, step up transformer or some more heating elements of the correct voltage. If the elements are old, its really probably a better - cheaper plan to just replace them with correctly rated voltage wise items. Lots of places make custom elements at a wide range of power ratings and there really very cheap, its common to pay sub £5 a foot of element over here for what ever rating you need.

    Equally you don't need anything like the sum of your machines name plate current rateings for incoming supply, get a industrial electrician in to spec things using correct derateings then add some head room for future expansion. If your already running everything a couple of minutes with a current clamp meter on your incoming supplier will give you some real world numbers that are far better to base things of.

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    Actually, you should be able to get a print-out for your current demands and uses from your current supplier.
    How much info depends on how smart of a meter you have.


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    Quote Originally Posted by adama View Post
    Edster, you seam to be missing this, if you retap a transformer delivering 400amps at 200 what ever volts, to 400 what ever volts, you half your current availability down to 200amps. Yes the wiring if suitably rated for the voltage is fine, but a transformer can only transform so much energy - its KVA rateings, its your choice weather you have that as more voltage or more current, but you don't get both.

    IMHO though your missing a far bigger issue, transformers are only so efficient. You don't want to be running everything off transformers, especially if you want to AC your space. The idle heat loss of that much transformation is lost then your paying more to remove that heat.

    The magnets should be easy to power with a transformer simply running backwards, its done the world over every day and transformers don't care less which way they have the power pass through them.

    The parts washer, me i would just run at the reduced voltage, yeah it half's the heating power, but it may prove to be enough, if its not, step up transformer or some more heating elements of the correct voltage. If the elements are old, its really probably a better - cheaper plan to just replace them with correctly rated voltage wise items. Lots of places make custom elements at a wide range of power ratings and there really very cheap, its common to pay sub £5 a foot of element over here for what ever rating you need.

    Equally you don't need anything like the sum of your machines name plate current rateings for incoming supply, get a industrial electrician in to spec things using correct derateings then add some head room for future expansion. If your already running everything a couple of minutes with a current clamp meter on your incoming supplier will give you some real world numbers that are far better to base things of.
    I don't need to figure anything out, I already have 400A of 480V and it's working fine.

    I'm just asking a simple question to satisfy my curiosity mostly. Do the power company's transformers have taps. It's the same wye connection for 208v as it is for 480v. It makes sense that they would have taps so they don't have to stock both types. I plan to contact my electrician, the one that installed our existing 480v service, and meet with him and the comed engineer at the site. But that's a while off.

    I don't know the kva rating of the transformer. It wasn't marked on the outside anywhere I could see it. But it's a large pad transformer, about the same size as other buildings in the industrial park. Some of those buildings are considerably larger than the one I'm looking at.


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