Closed Delta 120/240V 3-phase service

| |> |> | In article , phil-news- | | | |> |> | Specifically, the six-phase "star" and three-phase center-tapped |> |> | wye. With any two phases any number of others is a few transformers |> |> | away. |> |> |> |> I don't know which you mean by "three-phase center-tapped wye". Maybe you |> |> can pick it out from this police lineup: |> |> |> |> * * * * * * |> |> \ \ / * * * | \ / \ |> |> \ \ / / \ / | | \ / \ |> |> N---* *---N---* / \ / | *---N---* N * |> |> / / \ / \ / | | / |> |> / / \ *---N---* *---N---* *---N---* | / |> |> * * * * * |> |> |> |> 1 2 3 4 5 6 7 |> |> |> |> If you don't see the guilty party, maybe you can draw a picture :-) |> | |> | #2 be the culprit. Your "split-phase" three-phase from another |> | post. |> |> That is the same as the six-phase "star" or "6 star". So if you can't |> see any difference, that's because there isn't any. I would not have |> called this a "wye" of any sort since it doesn't look like a "Y". But |> it could be TWO Y's interleaved. | | No, not "interleaved" but split. Invert each phase, as in a center- | tapped transformer (I.e. split) and you're there.
You mean like having 2 three phase 208Y/120 transformers, one fed 180 degrees out of phase from the other, and combining their outputs with neutrals tied together? That's what I meant by interleaved. If that's not what you are saying, then I don't understand what it is you are saying.
|> To make this derived system, you need either: |> |> 1. 3 single phase transformer cores | | Kinda like they do now on the pole.
Yes. Except instead of using 120-volt-only transformers (there are such things ... just 2 lugs on the secondary), they need to use the 120/240 volt transformers (plenty of those around) and understand the concept to know how to wire it up.
Metering that could be an issue. In the case of the apartment building, individual tenants would be metered at 120/240 so it's not an issue. But if this needs to be metered in its "6 star" configuration, it can be done with 3 CTs, each carrying the 180-degree-opposite conductor pairs running in opposing directions just as a single CT would be used for single phase power.
|> 2. 1 three phase tranformer E-core | | Kinda...
It could be done. The manufacturing just has to provide a pair of 120 volt windings, or a series 120/240 tapped winding, and sufficient terminal board space to deal with it.
|> Then you need to wrap these cores with 3 primary windings and 3 secondary |> windings. Usually the secondaries go on the inside and the primaries go |> on the outside, so the secondary at lower voltage and higher current has |> less winding resistance. | | Ok, I'm confused. This is different how?
The difference is that a traditional E-core 208Y/120 transformer would have only ONE 120 volt winding per core bar (times the 3 core bars). Two such windings at 120 volt each, or a 120/240 volt series winding (connected in series inside the winding instead of at the terminal board) would be needed for the "6 star" configuration.
|> Each of the 3 secondary windings needs to be either: |> |> 1. a pair of 120 volt windings which you can wire in series |> 2. a single 240 volt winding with a center tap right in the middle | | Exactly (is there a difference?).
Yes, there is a difference. In #1 you have 4 wires coming from the secondary winding to the terminal board. In #2 you have 3 such wires because the winding is series connected, possibly a continuous single wire, inside the winding itself, and just tapped at a mid-point.
It's a difference in construction. Some people might be more familiar with one over the other.
|> All of the center points of these windings are wired/bonded together and |> grounded. Then each of the three phases will have two poles 180 degrees |> apart. Some people will call this six phases. | | Right; split-phase "wye".
Keep the "wye" in quotes, then; it's not really wye. I would never call it a wye at all. It's a 6 pointed radial star.
|> |> Note that drawings are NOT to scale (relative to voltage). |> | |> | Close enough for government work. |> | |> | |> | |> |> |> Can you describe an electrical system configuration which is capable of: |> |> |> |> |> |> 1. Supplying 120 and 240 volts (not 208 volts) in single phase to all |> |> |> single phase loads. |> |> | |> |> | Look harder at a center-tapped wye. There is only 60degrees between |> |> | the "negative" of phase-A and Phase-B. |> |> |> |> I don't know which I need to look at. |> | |> | #2 |> |> Let me relabel the terminals like so: |> |> C' B |> \ / |> \ / |> A----N----A' |> / \ |> / \ |> B' C |> |> Between A and A' you have 240 volts. |> Between B and B' you have 240 volts. |> Between C and C' you have 240 volts. |> Between A and B you have 208 volts. |> Between B and C you have 208 volts. |> Between C and A you have 208 volts. |> Between C' and A' you have 208 volts. |> Between A' and B' you have 208 volts. |> Between B' and C' you have 208 volts. |> Between A and N you have 120 volts. |> Between B and N you have 120 volts. |> Between C and N you have 120 volts. |> Between A' and N you have 120 volts. |> Between B' and N you have 120 volts. |> Between C' and N you have 120 volts. |> Between A and C' you have 120 volts. |> Between C' and B you have 120 volts. |> Between B and A' you have 120 volts. |> Between A' and C you have 120 volts. |> Between C and B' you have 120 volts. |> Between B' and A you have 120 volts. |> |> Which connection pair do you need to ask about? | | I don't. You seem to see a difference between this "star" and an | ordinary 3-phase "wye" that delivers residential 240V split-phase. | I don't see anything new or particularly interesting here, but am | trying.
A true WYE is not split phase. That makes a contradiction of terms. But if you know of a manufacturer that makes such a transformer AND calls it "split phase wye" or some such thing, please do point to their catalog reference. I've looked at a lot of transformer catalog info online and have never seen such a thing in a single transformer.
|> |> |> 2. Divides up the single phase load in three equal groups in order to |> |> |> maintain a balance on each of the three phases of the utility supply. |> |> | |> |> | How does it divide anything? An imbalance can still be placed on |> |> | any one (or two). |> |> |> |> Of course an imbalance can always happen, and likely will. But it is a |> |> statistical thing. If a building has 54 apartments, connecting 18 of them |> |> to phase A, 18 to phase B, and 18 to phase C, would be "balanced" enough |> |> for utility purposes. If the supply were coming in as 120/240DCT, then |> |> all of the apartments would be on just one of the phases and the phase |> |> loading would be as lopsided as if the entire building were supplied with |> |> single phase power. If the utility insists on balancing the phases and |> |> rejects single phase service for this reason, they will reject 120/240DCT. |> |> If the supply is 208Y/120, that would satisfy the utility (18 apartments |> |> supplied with phases A and B, 18 suppleid with B and C, and 18 supplied |> |> with C and A). But it would not satisfied the need to have 240 volts. |> | |> | Sure, but your "six-phase" is no different than the normal three- |> | phase "wye". At least I don't see it. |> |> The normal three phase WYE is just: |> |> B |> / |> / |> A----N |> \ |> \ |> C |> |> Between A and B you have 208 volts. |> Between B and C you have 208 volts. |> Between C and A you have 208 volts. |> Between A and N you have 120 volts. |> Between B and N you have 120 volts. |> Between C and N you have 120 volts. |> |> There aren't any other ways to connect, and no way to get 240 volts. | | That's funny, because that's exactly how I get the 240V for my house | off the 3-phases on the pole.
Which connections give you 240 volts? If you are getting 240 volts from A-B or from B-C or from C-A, and if the phase angles really are 120 degrees as a true three phase WYE would be, then you are going to get 139 volts at A-N, B-N, and C-N. I don't think that is what you want.
FYI, I did find one utility offering 240Y/139 service for some portions of their service area, as a replacement for 240D.
Maybe you are getting ONE phase of 120/240 via ONE split phase transformer tapped to ONE phase (connected L-N) or TWO phases (connected L-L) of the primary distribution lines. But just because there is three phase on the distribution does NOT mean you are getting it. You are most likely getting one of: 208Y/120 three phase (my grandfather actually did get this at his home), or 120/240 single phase, or that old 240DCT/120 setup.
|> |> |> |> ... that is not the "6 star" I described? |> |> | |> |> | I still don't see the difference between that and a center-tapped |> |> | wye. Again, I'm not a power jock, so may be missing something |> |> | subtile. |> |> |> |> Maybe you saw something I didn't see. Check the above police lineup. |> | |> | Nope. You saw it, just one of us isn't "getting it" (I could easily |> | be missing something - 65h work weeks do that after a while). |> |> OK, hope the above helps. | | Nope. I'm still wondering why you see your "star" as any different | than what we see on 90% of the poles in the country.
208Y/120 is _very_ different. 208Y/120 has THREE line wires coming out at 120 degree phase angle equal intervals. The "6 star" (maybe we can call it 240*/208/120) has SIX line wires coming out at 60 degree phase angle equal intervals.
If I provide you with exactly 3 transformers which are wired up with one winding for the primary voltage and one winding for the secondary at 120 volts, it can be wired up by connecting the primaries in whatever they need for the type of service (delta or wye) and connecting the secondaries in a wye configuration. There, you have 208Y/120 just like 90% of the three phase poles in the country (I'll just accept your stats of 90% as I do not know the actual figures).
I have never seen, and never heard of, any "6 star" or 240*/208/120 setup anywhere. I have never seen any utility tariff (I've looked through a few dozen over the past few years) that offers such a service.
I HAVE seen a couple three phase setups where a 120/240 volt pole pig was used, and only HALF of it was wired up to get 120 volts. I HAVE seen one manufacturer detail that they do make cans with the 120 volt windings in parallel internally, and still have 3 lugs with one of them not connected. So these are not necessarily a case of wasting half the capacity. The 3rd lug may simply be there are part of the process of manufacturing only one set of empty cans instead of two different sets.
Reply to
phil-news-nospam
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| krw wrote: |> |> |> > |> > What makes you think that its up to you to chose? The utility |> > company is going to tell you what is available. The elevator company is |> > going to tell you what they need, as well. As usual, you're playing |> > another of your long winded, and useless games of 'What if'... |> |> What if Phil bought his own bigass transformer? | | | Progress Energy, who bought Florida Power, wouldn't let you provide | any transformers. They did the calculations, and set their own | transformers. Three phase availability was determined by your location, | but generally any building above a certain level was three phase. Even | small convenience stores and gas stations are three phase around here. | The only home I've seen with an elevator had three phase power, along | with an Onan diesel three phase generator with an automatic transfer | switch.
Maybe Florida has no provision to require the utility to provide standard voltages (like 240 volts). Some other states do. And such a requirement is NOT a problem to meet (although if you want to change an existing setup I can expect you have to pay the full costs).
Do you know if that home has 208Y/120 or 240DCT/120 ?
This system is overkill for a single home:
* * \ / *--*--* / \ * *
But this system could do the job adequately:
* / *--*--* \ *
Which to choose depends on whether the distribution supply needs to be kept in balance or not. Utilities require (and this is a reasonable requirement) that larger services be three phase so they can keep the lines in the area in balance.
I've not seen generators that readily do either of these diagrammed examples, so I suspect that house is either 208Y/120 or 240DCT/120. And the 240DCT/120 can be done at least three different ways.
Reply to
phil-news-nospam
| |>| What makes you think that its up to you to chose? The utility |>| company is going to tell you what is available. The elevator company is |>| going to tell you what they need, as well. As usual, you're playing |>| another of your long winded, and useless games of 'What if'... |> |> | I think that logically, the process goes something like this. | | 1. The architect or building contractor responsible for the | electrical system needs to research the utility tariffs and policies | and determine what services are available. | | 2. Further research may be necessary to see what services are | available at the specific location of the building under construction. | | | This may be different then #1. | | 3. Given the available choices, it is up to the person designing the | electrical system within the building the most economical and useful | service, given the specific needs of the building (elevators, HVAC, | pumps, machine shop tools, etc.) That is, should it be 120/208, | 120/240, volt single phase or three phase, open wye, or closed-delta, | etc. | | #3 is the most interesting and the most difficult, apparently, from | the comments offered on this thread. It doesn't seem that there are | any carved-in-stone rules for what is best, only tradeoffs and | different opinions. | | Have I got this right?
Basically, yes. One point is that to choose 120/240 when the building size (in terms of load) is above the point where three phase is required means a greater cost. Unlike single homes, such developments, even if residential in nature, are treated like commercial, at least up to the point where the tenant metering takes place. So the developer has to pay most or all of the electrical service installation costs. Since traditional 208Y/120 is lower in cost (one stock transformer, one entrance disconnect), it may well be the one chosen. It can cost more to then get special appliances for each unit to operate at 208 volts. Or, as appears to be the case quite often, the developer just passes the cost on to the owner(s) or tenants in the form of poorly chosen appliances, or leaving it up to condo buyers to find the 208 volt appliances, or suffer with 240 volt appliances. The fact that so many cases are decided in bad ways does not mean better choices are not available; they just cost a little more.
I do know some apartment buildings are large enough to have transformers on each floor. I was in one building many years ago that had 8 units on each of 12 floors. There was a transformer on each floor, and metering for each tenant was in a small room on the same floor. The meter room did not have the transformer. That would certainly be essential of the feed was at distribution voltage (I don't know what it was in that building as I did not actually inspect the rooms). I do know it had 208 volts to each unit, and specially bought 208 volt appliances. But they could have just done this with a single phase transformer on each floor and saved on the cost of appliances but getting normal 240 volt ones. In this case, it would not have been any more expensive, and it would have been at least as well balanced across the distribution phases as the existing setup. Any needs for three phase power could have been satisfied with a separate three phase transformer at the top or bottom of the building. It would have to be separately metered, anyway.
Reply to
phil-news-nospam
| snipped-for-privacy@ipal.net wrote: |> |> Maybe you should read some of the tariffs. Most jurisdictions do have |> some requirements that certain services must be made available of so |> requested. The only "what if" here is "what if someone knew what they |> were allowed to really ask for". | | | Obviously, you don't and you've been flogging another dead horse. | You can take any simple subject and turn it into mind numbing drivel. | You've flogged this one for a week and made zero progress. Even if you | got answers, they would only be valid for one location, not the entire | planet earth.
How do you know there is "zero progress"? Just because I have failed to educate YOU on the issue does not mean I have failed to open the eyes of others to the issues AND solutions.
| You bitch about no availability of 208 volt appliances. How many do | you see that are marked 240 VAC only? I see a lot that are marked | 208-240 VAC. So your water heater is a few volts low. It won't make | much difference in the output. If you buy at the right places, 208 volt | stuff isn't hard to find, even in the deep south. If you are in an | apartment, it is up to the landlord to provide the major appliances, and | repair or replace them when they quit. So, if the building is big | enough, they are supplied three phase. no matter how much you want to | yak about what ifs, no one really gives a damn, except the local power | company, and the owner of the building.
I have real experiences with such low voltage issues.
My grandfather had this issue with his home when he obtained three phase service for his home to power three phase motors in his shop. He had problems with a stove that was slow to heat up, an electric dryer motor that burned out a couple times, and occiaisional issues with the air conditioning. Apparently he needed 240DCT/120 and they gave him 208Y/120.
I worked in a commercial building at an ISP at the beginning of the popularity of the internet. As the heat output in the computer room went up, and it was expanded into a 2nd room, it taxed the A/C system more. The A/C system was rated for that level of heat, but kept failing anyway. The building was originally single phase, but was converted over to three phase many years prior to our occupancy (apparently due to one tenant installing some equipment that needed some major amount of power. The A/C systems were single phase, and now running on 208 volts. The A/C servicing company had to special order a 208 volt single phase motor to replace the 240 volt single phase motors that kept burning out. Once the 208 volt motor was in, it worked fine.
The fact is, there are problems with 208 volt services. Yes, there are appliances that can work on 208 volts. Some work less well. Some work just fine. Some will fail.
If it is a building where the owner buys the appliances, the owner needs to consider the costs of those appliances as part of the overall cost savings strategy. In cases where the residents have to buy their own, such as many condominium arrangemnts, this is a cost passed on to the residents (so the developer might not give a damn).
To be cheap, landlords might well buy the very cheapest appliances that are available, which might be 240 volt just because there is a larger market for these. Then when residents complain that it takes longer to cook food and recover heat in the water tank, the landlord just says to accept it or move out at the end of the lease. Do not under any case think that landlords will be sure there are no problems.
I have pointed out the alternative to get true 240 volts. Not all cases would be able to utilize that without extra costs. Certainly a retrofit won't be free. But in many cases it can be a no greater cost to supply genuine split-phase single phase 120/240 volt service to residential units.
Part of the problem is that too many developers and engineers continue to think inside the 208 volt box. They think it is an accepted norm (and it is so relative to the people they deal with: landlords and developers who can shield them from the real problems of residents). So they don't even think about it. They just whack out a variation of the same old same old and people are then stuck with no improvement and have to accept it.
Reply to
phil-news-nospam
| |> snipped-for-privacy@ipal.net wrote: |> > |> > Maybe you should read some of the tariffs. Most jurisdictions do have |> > some requirements that certain services must be made available of so |> > requested. The only "what if" here is "what if someone knew what they |> > were allowed to really ask for". | | |> Obviously, you don't and you've been flogging another dead horse. |> You can take any simple subject and turn it into mind numbing drivel. |> You've flogged this one for a week and made zero progress. Even if you |> got answers, they would only be valid for one location, not the entire |> planet earth. | |> You bitch about no availability of 208 volt appliances. How many do |> you see that are marked 240 VAC only? I see a lot that are marked |> 208-240 VAC. So your water heater is a few volts low. It won't make |> much difference in the output. | | Power is a function of the voltage squared. So a 3kW heater at 240v | becomes 2.25kW at 208v. It may not be significant if it's used for storage | heating but as an instantaneous heater it would matter.
It depends on how many people want to use hot water and how _soon_ after a previous person has used it up.
It does appear that modern ranges with electronic controls on cooktops and ovens do a fine job with 208 volts or 240 volts. They just have more "on time" at 208 volts than at 240 volts for whatever setting is involved. My father's range at 240 volts is on about 75% of the time at the top setting. I suspect it will work fine at 208 volts.
Other things might not do so well at 208 volts. It can, for example, affect the sustained temperature a house can be kept at when electric heat is used and the outside temperature is in a deep cold spell.
I think the USA might well have been better off with "everything 240 volts" as is the case in the UK (though I would not want those ring circuits).
I described a while back an electrical system design that I would put in place if it were my say to do so, if I could have done it way back in time when changing over would be little or no cost, based on knowledge I have today (they did not have it back then, over 100 years ago). That system would be 288 volts always connected line to line. It would have 144 volts line to neutral in single phase systems (e.g. split phase as the USA has now). It would have 166 volts line to neutral in three phase systems in a star/wye arrangement. Everything except incandescent lights would be on 288 volts. Nothing would use the 144 or 166 volt connections. There would be a small transformer serving a light or group of lights to step the 288 volts down to 12 or 12/24 volts. This would mean the use of filaments that would be thicker, and could run hotter. That should at least make up for the loss in the transformer (as is now the case to justify the use of low voltage lighting). Fluorescent lighting could be run directly on the 288 volt connection. My system would have avoided the voltage discrepancy issues the USA currently has between 208 volts and 240 volts, while having a lower "relative to ground" voltage in the wiring than the UK has.
Reply to
phil-news-nospam
Generally, if you are a renter, you experience a lack of choice in many aspects of your housing. You may have lack of choice in being subjected to noise from the Bickersons in the apartment above you or the sax player next door. You may not have the choice of doing your laundry in your unit, or painting your walls lime green, or having your own parking space. If your landlord provides a 240V dryer on a 208V circuit, then yes... your clothes will take longer to dry. You have no choice. The lower voltage might have the dryer heater cycle on for a longer period of time, but the maximum wattage delivered will definately be less.
In the US, at least, condo unit owners may have it better, in that they might have a few more things under their control. Most multi-unit condos have an in-unit washer and dryer, so at least you might have a choice about getting the dryer at the correct voltage.
I would argue that its still more of a hassle though (for most people), and it may be hard to find or order the one you want that runs properly on 208V. You will probably be faced with increased expense, as well. Perhaps the one currently on sale has only the 240V element.
Beachcomber
Reply to
Beachcomber
Either that or CT secondaries. Same difference.
IF there is any advantage (doubt it), they'll figure out how to wire it up. It's rather obvious.
Yes, that's why I see nothing unique about your "idea". It's done today, except there is no need for the inversion.
There is likely a reason they don't. Though in your case of an apartment building they do, though likely with individual transformers. It's done on 90% of the poles in the country.
No different than what happens on 90% of the poles in the country, except those are in three cans rather than one.
A distinction without a difference. WHo cares how many screws are on the terminal board?
Sure. If there is no reason to make a widget there is a good chance that most are unfamiliar with the widget.
"Wye" is usually in quotes, even in a normal implementation.
Certainly it is, on 90% of the poles in the country.
The CT on any leg.
It's a "wye" not a delta. Three transformers with CT secondaries from A-N, B-N, and C-N. You just made you "star" configuration.
I didn't say an individual home was getting three phase, but it's there on the pole. ...including your "star".
Look at 100 random poles. You'll see 90 of them wired as 3-phase "wye" (really doesn't matter if they are delta). The secondaries are CTed, so you have the six points of your "star". Nothing new here.
You've seen it, just haven't called it that. There is no point to it, so it isn't named.
Irrelevant manufacturing detail.
Reply to
krw
...and the house to the north gets:
* * \ / *--* \ *
...and the house to the south gets:
*
/ *--* / \ * *
And pretty soon you have something on the pole that looks kinda like:
* * \ / *--*--* / \ * *
Three phase also sorta allows them to deliver more power for a given conductor size.
Reply to
krw
208Y/120 They also had a couple 12" wells with three phase pumps, and a diesel powered backup pump.
Reply to
Michael A. Terrell
I haven't seen people agreeing with you, or supporting your theories.
Sure you do. We've all seen brownouts. My line voltage was about 105 volts for a month while the area was rebuilt after some hurricanes. It was 27 volts for half a day. Fluorescent lights didn't work right at 105 volts, but it didn't bother the refrigerators.
Apparently he needed the proper appliances. He made the decision to convert to three phase, so don't blame the equipment that he was to cheap to convert, or replace.
One TV transmitter site I worked at was supplied with 480 Wye service only. That was fine for most of the transmitter and cooling system, but the crystal ovens and oscillators ran on 120 single phase so we had to install three 2 KVA 480 to 120 volt transformers to power everything else.
I've lost three air conditioner compressors in the last nine years at my home, and all were running at the rated voltages. Microdyne lost at least a half dozen a year, all were three phase, and running the right voltage. How can you prove it was under voltage, not that the air conditioner couldn't handle the load? Tty air conditioning a TV station's control room and studios. We had a five ton unit just for the VTRs and effects racks.
Gee, Phil. If the owner has to buy and maintain the appliances, why would they buy the cheapest shit made? They aren't that stupid. Well, at least around here. Their cost for the appliances are in bulk, and at wholesale. A lot of damage to their buildings is avoided by supplying the appliances, and they can charge higher rent. The longer an appliance lasts, the more money they make off it.
Where is this? Defects in a building can get the landlord and or management company fined. for failing to make repairs in an acceptable time. In severe cases, the building can be condemned. After that, the owner has a little time to do the repairs, and get a new certificate of occupancy. You're just trying to blow smoke up my ass, as usual.
Name ONE thing a renter needs to run on 240 volts that isn't supplied by a decent landlord.
They do it because it works reliably, and at a reasonable cost. It really isn't up to you, and there is no valid need for any 240 VAC for anything the owner doesn't supply.
Reply to
Michael A. Terrell
| |> |> | |> |> |> |> | In article , phil-news- |> | |> | | |> |> That is the same as the six-phase "star" or "6 star". So if you can't |> |> see any difference, that's because there isn't any. I would not have |> |> called this a "wye" of any sort since it doesn't look like a "Y". But |> |> it could be TWO Y's interleaved. |> | |> | No, not "interleaved" but split. Invert each phase, as in a center- |> | tapped transformer (I.e. split) and you're there. |> |> You mean like having 2 three phase 208Y/120 transformers, one fed 180 degrees |> out of phase from the other, and combining their outputs with neutrals tied |> together? That's what I meant by interleaved. If that's not what you are |> saying, then I don't understand what it is you are saying. | | Either that or CT secondaries. Same difference. | |> |> To make this derived system, you need either: |> |> |> |> 1. 3 single phase transformer cores |> | |> | Kinda like they do now on the pole. |> |> Yes. Except instead of using 120-volt-only transformers (there are such |> things ... just 2 lugs on the secondary), they need to use the 120/240 volt |> transformers (plenty of those around) and understand the concept to know |> how to wire it up. | | IF there is any advantage (doubt it), they'll figure out how to wire | it up. It's rather obvious.
There is an advantage to having genuine 240 volts. Not all circumstances make it easy to use separate single phase transformers. The ones that do would already have multiple transformers. Otherwise it increases cost. And there are no "6 star" transformers made (yet).
|> Metering that could be an issue. In the case of the apartment building, |> individual tenants would be metered at 120/240 so it's not an issue. But |> if this needs to be metered in its "6 star" configuration, it can be done |> with 3 CTs, each carrying the 180-degree-opposite conductor pairs running |> in opposing directions just as a single CT would be used for single phase |> power. | | Yes, that's why I see nothing unique about your "idea". It's done | today, except there is no need for the inversion.
Maybe there is a confusion here. CT could mean "center tap" or it could mean "current transformer". In the above, I mean "current transformer" for the purpose of metering.
|> |> 2. 1 three phase tranformer E-core |> | |> | Kinda... |> |> It could be done. The manufacturing just has to provide a pair of 120 |> volt windings, or a series 120/240 tapped winding, and sufficient terminal |> board space to deal with it. | | There is likely a reason they don't. Though in your case of an | apartment building they do, though likely with individual | transformers. It's done on 90% of the poles in the country.
What is done in on 90% of the poles? The "6 star" suggest is certainly not.
|> |> Then you need to wrap these cores with 3 primary windings and 3 secondary |> |> windings. Usually the secondaries go on the inside and the primaries go |> |> on the outside, so the secondary at lower voltage and higher current has |> |> less winding resistance. |> | |> | Ok, I'm confused. This is different how? |> |> The difference is that a traditional E-core 208Y/120 transformer would have |> only ONE 120 volt winding per core bar (times the 3 core bars). Two such |> windings at 120 volt each, or a 120/240 volt series winding (connected in |> series inside the winding instead of at the terminal board) would be needed |> for the "6 star" configuration. | | No different than what happens on 90% of the poles in the country, | except those are in three cans rather than one.
The "6 star" is not done anywhere I have ever heard of. You must be referring to a common WYE, which is not the same thing (WYE is a "3 star" not a "6 star").
|> |> Each of the 3 secondary windings needs to be either: |> |> |> |> 1. a pair of 120 volt windings which you can wire in series |> |> 2. a single 240 volt winding with a center tap right in the middle |> | |> | Exactly (is there a difference?). |> |> Yes, there is a difference. In #1 you have 4 wires coming from the secondary |> winding to the terminal board. In #2 you have 3 such wires because the |> winding is series connected, possibly a continuous single wire, inside the |> winding itself, and just tapped at a mid-point. | | A distinction without a difference. WHo cares how many screws are | on the terminal board?
You need more screws for the extra wires. How many depends on if you want to double up on a single lug or not.
|> It's a difference in construction. Some people might be more familiar with |> one over the other. | | Sure. If there is no reason to make a widget there is a good chance | that most are unfamiliar with the widget. | |> |> All of the center points of these windings are wired/bonded together and |> |> grounded. Then each of the three phases will have two poles 180 degrees |> |> apart. Some people will call this six phases. |> | |> | Right; split-phase "wye". |> |> Keep the "wye" in quotes, then; it's not really wye. I would never call it |> a wye at all. It's a 6 pointed radial star. | | "Wye" is usually in quotes, even in a normal implementation.
Really? I see it more NOT in quotes. The term WYE is a longish form of "Y" which is a depiction of a 3 pointed star configuration, not 6. The "*" more resembles 6 under most fonts (some have 8, but that's another issue).
|> |> Which connection pair do you need to ask about? |> | |> | I don't. You seem to see a difference between this "star" and an |> | ordinary 3-phase "wye" that delivers residential 240V split-phase. |> | I don't see anything new or particularly interesting here, but am |> | trying. |> |> A true WYE is not split phase. That makes a contradiction of terms. |> But if you know of a manufacturer that makes such a transformer AND |> calls it "split phase wye" or some such thing, please do point to |> their catalog reference. I've looked at a lot of transformer catalog |> info online and have never seen such a thing in a single transformer. | | Certainly it is, on 90% of the poles in the country.
Since well more than 10% of poles have a traditional 3 pole wye, there cannot be 90% with a 6 pole three phase star arrangement.
|> |> Between A and B you have 208 volts. |> |> Between B and C you have 208 volts. |> |> Between C and A you have 208 volts. |> |> Between A and N you have 120 volts. |> |> Between B and N you have 120 volts. |> |> Between C and N you have 120 volts. |> |> |> |> There aren't any other ways to connect, and no way to get 240 volts. |> | |> | That's funny, because that's exactly how I get the 240V for my house |> | off the 3-phases on the pole. |> |> Which connections give you 240 volts? | | The CT on any leg.
Be specific. First of all you know you need TWO connection points for a voltage. Simply saying "CT" (which I assume to mean "center tap" instead of "current transformer") means ONE connection. You get no voltage from one connection.
So how do you get 240 volts from a 208Y/120 wired transformer bank? Answer: you don't.
|> If you are getting 240 volts from |> A-B or from B-C or from C-A, and if the phase angles really are 120 degrees |> as a true three phase WYE would be, then you are going to get 139 volts |> at A-N, B-N, and C-N. I don't think that is what you want. | | It's a "wye" not a delta. Three transformers with CT secondaries | from A-N, B-N, and C-N. You just made you "star" configuration.
What are you labeling A-N, B-N, and C-N? The primaries or secondaries? Your statement "CT secondaries from A-N, B-N, and C-N" makes no sense. If there were 3 split-phase secondaries involved, there would be a lot more connection points than just these three. Even if all the center taps were connected together, you would still have 6 connection points to label. Starting at A, that runs to F.
|> FYI, I did find one utility offering 240Y/139 service for some portions |> of their service area, as a replacement for 240D. |> |> Maybe you are getting ONE phase of 120/240 via ONE split phase transformer |> tapped to ONE phase (connected L-N) or TWO phases (connected L-L) of the |> primary distribution lines. But just because there is three phase on the |> distribution does NOT mean you are getting it. You are most likely getting |> one of: 208Y/120 three phase (my grandfather actually did get this at his |> home), or 120/240 single phase, or that old 240DCT/120 setup. | | I didn't say an individual home was getting three phase, but it's | there on the pole. ...including your "star".
It's not there if what's on the pole is 208Y/120, which most poles supplying three phase power have. The only voltages available are 208 volts and 120 volts. Every possible pairing of 2 connections on these very common setups gives either 208 volts or 120 volts. I listed them previously. I left none out. None have 240 volts.
| | |> |> |> |> OK, hope the above helps. |> | |> | Nope. I'm still wondering why you see your "star" as any different |> | than what we see on 90% of the poles in the country. |> |> 208Y/120 is _very_ different. 208Y/120 has THREE line wires coming out at |> 120 degree phase angle equal intervals. The "6 star" (maybe we can call |> it 240*/208/120) has SIX line wires coming out at 60 degree phase angle |> equal intervals. | |> If I provide you with exactly 3 transformers which are wired up with one |> winding for the primary voltage and one winding for the secondary at 120 |> volts, it can be wired up by connecting the primaries in whatever they |> need for the type of service (delta or wye) and connecting the secondaries |> in a wye configuration. There, you have 208Y/120 just like 90% of the |> three phase poles in the country (I'll just accept your stats of 90% as I |> do not know the actual figures). | | Look at 100 random poles. You'll see 90 of them wired as 3-phase | "wye" (really doesn't matter if they are delta). The secondaries | are CTed, so you have the six points of your "star". Nothing new | here.
You really think that?
Sure, a 120/240 volt split phase transformer used normally for single phase service could be used for 208Y/120 by connecting only ONE SIDE. And it might be done in a few places. But it would be very rare since it is a waste of half the transformer capacity, and thus a higher cost than needed. They do make transformers that can deliver their entire capacity on just 2 lugs at 120 volts. There is no center tap. Or if there is, the center of 120 is 60 so it would not be used.
The majority of 208Y/120 services derived using single phase pole pigs is done with 3 cans that have 120 volt ONLY secondaries.
|> I have never seen, and never heard of, any "6 star" or 240*/208/120 setup |> anywhere. I have never seen any utility tariff (I've looked through a few |> dozen over the past few years) that offers such a service. | | You've seen it, just haven't called it that. There is no point to | it, so it isn't named.
So you really do have 208Y/120 mixed up with "6 star" or whatever someone else might refer to it as.
|> I HAVE seen a couple three phase setups where a 120/240 volt pole pig was |> used, and only HALF of it was wired up to get 120 volts. I HAVE seen one |> manufacturer detail that they do make cans with the 120 volt windings in |> parallel internally, and still have 3 lugs with one of them not connected. |> So these are not necessarily a case of wasting half the capacity. The 3rd |> lug may simply be there are part of the process of manufacturing only one |> set of empty cans instead of two different sets. | | Irrelevant manufacturing detail.
It's very relevant. It decides if the transformer has only 120 volts or if it has 120/240 volts. It decides in the case of 2 separate 120 volt windings whether they can be paralleled or not (and they need to be in parallel for the 208Y/120 service). The only transformer design that allows an external choice of configuring 120 volt parallel or 120/240 volt series center tapped is one with 4 lugs. I have seen such a transformer. But virtually all the rest of 3 lugs or 2 lugs.
Reply to
phil-news-nospam
|> Do you know if that home has 208Y/120 or 240DCT/120 ? |> |> This system is overkill for a single home: |> |> * * |> \ / |> *--*--* |> / \ |> * * |> |> But this system could do the job adequately: |> |> * |> / |> *--*--* |> \ |> * | | ...and the house to the north gets: | | * * | \ / | *--* | \ | * | | ...and the house to the south gets: | | | * | / | *--* | / \ | * * | | And pretty soon you have something on the pole that looks kinda | like: | | * * | \ / | *--*--* | / \ | * *
It would certainly be possible to deliver three such configurations to three different houses from the same pole with three transformers of the 120/240 split phase design. And you say this has been done? If so, then I think that's cool. But that is not what is generally done in 99% or more of three phase installations.
|> Which to choose depends on whether the distribution supply needs to be kept |> in balance or not. Utilities require (and this is a reasonable requirement) |> that larger services be three phase so they can keep the lines in the area |> in balance. | | Three phase also sorta allows them to deliver more power for a given | conductor size.
When comparing single phase L-L voltage to a delta with the same voltage that is true by 15.47%. If you take 240 delta, and compare it to 240 single phase 2 wire (regardless of where the grounding point is on either system), the 240 delta has more power in the same conductor size.
But if you look at both systems relative to the center of the system, the single phase is 2x 120 volts whereas the three phase is 3x 139 volts. You get the extra power based on the relative system voltage effectively being higher. Compare 120/240 volt single phase to 240Y/139 three phase. Put in 6 conductors, 3 per pole for 120/240 volt single phase and 2 per pole for 240Y/139 three phase. The latter gets its gain by virtue of the higher voltage.
Compare 208Y/120 to 120/240 and there is no such gain. It's all in the voltage comparison where delta allows it to look like it has a lower voltage than it really does.
Reply to
phil-news-nospam
| snipped-for-privacy@ipal.net wrote: |> |> |> | krw wrote: |> |> |> |> |> |> > |> |> > What makes you think that its up to you to chose? The utility |> |> > company is going to tell you what is available. The elevator company is |> |> > going to tell you what they need, as well. As usual, you're playing |> |> > another of your long winded, and useless games of 'What if'... |> |> |> |> What if Phil bought his own bigass transformer? |> | |> | |> | Progress Energy, who bought Florida Power, wouldn't let you provide |> | any transformers. They did the calculations, and set their own |> | transformers. Three phase availability was determined by your location, |> | but generally any building above a certain level was three phase. Even |> | small convenience stores and gas stations are three phase around here. |> | The only home I've seen with an elevator had three phase power, along |> | with an Onan diesel three phase generator with an automatic transfer |> | switch. |> |> Maybe Florida has no provision to require the utility to provide standard |> voltages (like 240 volts). Some other states do. And such a requirement |> is NOT a problem to meet (although if you want to change an existing setup |> I can expect you have to pay the full costs). |> |> Do you know if that home has 208Y/120 or 240DCT/120 ? |> | | | 208Y/120 They also had a couple 12" wells with three phase pumps, | and a diesel powered backup pump.
OK, so they didn't have any 240 volt supply.
Reply to
phil-news-nospam
| charles wrote: |> |> Power is a function of the voltage squared. So a 3kW heater at 240v |> becomes 2.25kW at 208v. It may not be significant if it's used for storage |> heating but as an instantaneous heater it would matter. | | | Gee thanks for that lesson. I've know and used it since the '50s. | If you need that extra bit of heat, you can buy the proper heating | element. Not at the over the counter type 'DIY' dumps, but at a real | plumbing supply house.
Which means it is more expensive. And in many cases they have to special order it. I've already experienced the special order cost case with a 208 volts single phase motor (it was twice as much as a 240 volt motor of the same HP and mounting).
Reply to
phil-news-nospam
| |>Part of the problem is that too many developers and engineers continue to |>think inside the 208 volt box. They think it is an accepted norm (and it |>is so relative to the people they deal with: landlords and developers who |>can shield them from the real problems of residents). So they don't even |>think about it. They just whack out a variation of the same old same old |>and people are then stuck with no improvement and have to accept it. |> | | Generally, if you are a renter, you experience a lack of choice in | many aspects of your housing. You may have lack of choice in being | subjected to noise from the Bickersons in the apartment above you or | the sax player next door. You may not have the choice of doing your | laundry in your unit, or painting your walls lime green, or having | your own parking space. If your landlord provides a 240V dryer on a | 208V circuit, then yes... your clothes will take longer to dry. You | have no choice. The lower voltage might have the dryer heater cycle | on for a longer period of time, but the maximum wattage delivered will | definately be less.
Yes, landlords go cheap on lots of things, not just the power.
The last apartment I lived in had 120/240. The complex consisted of 60 some buildings with 12 apartments each. Each building had a single phase pad mount. I don't know what its rating was as the nameplate was not visible (probably inside and I didn't care to get into it). Presumably it could have been as much as 167 KVA, the largest single phase pad mount I've seen in catalogs. That is probably fine for 12 apartment units.
| In the US, at least, condo unit owners may have it better, in that | they might have a few more things under their control. Most | multi-unit condos have an in-unit washer and dryer, so at least you | might have a choice about getting the dryer at the correct voltage.
Yes, if they go buy one for the condo, they can choose between the $400 240 volt model and the $440 208 volt special order model. If they already have one from the house they now live in and want to take it with them, it's probably a 240 volt model.
| I would argue that its still more of a hassle though (for most | people), and it may be hard to find or order the one you want that | runs properly on 208V. You will probably be faced with increased | expense, as well. Perhaps the one currently on sale has only the 240V | element.
Exactly. The costs for 208 volt models can be from both the smaller market as well as the special order handling.
Reply to
phil-news-nospam
| snipped-for-privacy@ipal.net wrote: |> |> |> | snipped-for-privacy@ipal.net wrote: |> |> |> |> Maybe you should read some of the tariffs. Most jurisdictions do have |> |> some requirements that certain services must be made available of so |> |> requested. The only "what if" here is "what if someone knew what they |> |> were allowed to really ask for". |> | |> | |> | Obviously, you don't and you've been flogging another dead horse. |> | You can take any simple subject and turn it into mind numbing drivel. |> | You've flogged this one for a week and made zero progress. Even if you |> | got answers, they would only be valid for one location, not the entire |> | planet earth. |> |> How do you know there is "zero progress"? Just because I have failed to |> educate YOU on the issue does not mean I have failed to open the eyes of |> others to the issues AND solutions. | | | I haven't seen people agreeing with you, or supporting your theories.
Maybe if you look beyond just who is posting, you'd see more. There are already some that are posting, too. The rest are quiet and you cannot tell if they agree or not.
|> | You bitch about no availability of 208 volt appliances. How many do |> | you see that are marked 240 VAC only? I see a lot that are marked |> | 208-240 VAC. So your water heater is a few volts low. It won't make |> | much difference in the output. If you buy at the right places, 208 volt |> | stuff isn't hard to find, even in the deep south. If you are in an |> | apartment, it is up to the landlord to provide the major appliances, and |> | repair or replace them when they quit. So, if the building is big |> | enough, they are supplied three phase. no matter how much you want to |> | yak about what ifs, no one really gives a damn, except the local power |> | company, and the owner of the building. |> |> I have real experiences with such low voltage issues. | | | Sure you do. We've all seen brownouts. My line voltage was about 105 | volts for a month while the area was rebuilt after some hurricanes. It | was 27 volts for half a day. Fluorescent lights didn't work right at 105 | volts, but it didn't bother the refrigerators.
Yes, I have seen brownouts before. Some things work OK at reduced voltage and some things done. You get both in each class of appliance.
|> My grandfather had this issue with his home when he obtained three phase |> service for his home to power three phase motors in his shop. He had |> problems with a stove that was slow to heat up, an electric dryer motor |> that burned out a couple times, and occiaisional issues with the air |> conditioning. Apparently he needed 240DCT/120 and they gave him 208Y/120. | | | Apparently he needed the proper appliances. He made the decision to | convert to three phase, so don't blame the equipment that he was to | cheap to convert, or replace.
More likely he didn't know. I didn't discuss lots of details with him at the time, since I was only 12 years old. I knew WHAT three phase was for, but I had no idea how the systems were configured, or that it really mattered. What I knew then was that he did say the voltage was too low and he was trying to get the power company to fix it.
I suspect when he asked for three phase, he didn't know the choices and might have been expecting to get 240DCT/120. I don't know if his shop equipment needed 240 or 208. I just know he was trying to get it redone up to the day he died. I don't know why it was not redone. I can only guess and many possible explanations seem plausible.
| One TV transmitter site I worked at was supplied with 480 Wye service | only. That was fine for most of the transmitter and cooling system, but | the crystal ovens and oscillators ran on 120 single phase so we had to | install three 2 KVA 480 to 120 volt transformers to power everything | else.
And the transmitter manufacturer didn't integrate things so that it could be connected to a single power source?
|> I worked in a commercial building at an ISP at the beginning of the |> popularity of the internet. As the heat output in the computer room |> went up, and it was expanded into a 2nd room, it taxed the A/C system |> more. The A/C system was rated for that level of heat, but kept failing |> anyway. The building was originally single phase, but was converted |> over to three phase many years prior to our occupancy (apparently due |> to one tenant installing some equipment that needed some major amount |> of power. The A/C systems were single phase, and now running on 208 |> volts. The A/C servicing company had to special order a 208 volt single |> phase motor to replace the 240 volt single phase motors that kept burning |> out. Once the 208 volt motor was in, it worked fine. | | | I've lost three air conditioner compressors in the last nine years at | my home, and all were running at the rated voltages. Microdyne lost at | least a half dozen a year, all were three phase, and running the right | voltage. How can you prove it was under voltage, not that the air | conditioner couldn't handle the load? Tty air conditioning a TV | station's control room and studios. We had a five ton unit just for the | VTRs and effects racks.
The motors burned out very frequently, generally lasting no more than two weeks as summer come on along with the new computers in place. Once the 208 volt motor was put in, the problem completely went away. Clearly the A/C servicing people believed it was a voltage issue. Based on what changes took place, I'd agree it was.
That doesn't mean there can't be failures for other reasons. But in the above case, it was clearly voltage with 99% confidence. Go ahead and pick on the 1% if you want.
|> The fact is, there are problems with 208 volt services. Yes, there are |> appliances that can work on 208 volts. Some work less well. Some work |> just fine. Some will fail. |> |> If it is a building where the owner buys the appliances, the owner needs |> to consider the costs of those appliances as part of the overall cost |> savings strategy. In cases where the residents have to buy their own, |> such as many condominium arrangemnts, this is a cost passed on to the |> residents (so the developer might not give a damn). |> |> To be cheap, landlords might well buy the very cheapest appliances that |> are available, which might be 240 volt just because there is a larger |> market for these. | | | Gee, Phil. If the owner has to buy and maintain the appliances, why | would they buy the cheapest shit made? They aren't that stupid. Well, | at least around here. Their cost for the appliances are in bulk, and at | wholesale. A lot of damage to their buildings is avoided by supplying | the appliances, and they can charge higher rent. The longer an | appliance lasts, the more money they make off it.
Actually, in a great many cases, they _are_ that stupid. While motor based appliances might well burn up, heating element appliances may have no issued. BTW, dryers tend to have the motor on L-N, not L-L. So the motor would be getting what it expects even on 208Y/120. Ranges and water heaters are NOT going to have a shortened life due to running on a reduced voltage. So they _can_ get away with using 240 volt stuff on 208 volts.
|> Then when residents complain that it takes longer to |> cook food and recover heat in the water tank, the landlord just says to |> accept it or move out at the end of the lease. Do not under any case |> think that landlords will be sure there are no problems. | | | Where is this? Defects in a building can get the landlord and or | management company fined. for failing to make repairs in an acceptable | time. In severe cases, the building can be condemned. After that, the | owner has a little time to do the repairs, and get a new certificate of | occupancy. You're just trying to blow smoke up my ass, as usual.
I'd like to see them get fined for such things. Generally, they don't.
|> I have pointed out the alternative to get true 240 volts. Not all cases |> would be able to utilize that without extra costs. Certainly a retrofit |> won't be free. But in many cases it can be a no greater cost to supply |> genuine split-phase single phase 120/240 volt service to residential units. | | | Name ONE thing a renter needs to run on 240 volts that isn't supplied | by a decent landlord.
In renting situations, probably nothing. But in at least a lot of cases, and maybe most, where 208 volts is supplied, the appliances are 240 volt models.
When the building is converted to condo, the picture changes. And this is where most of the reports of this issue come from.
|> Part of the problem is that too many developers and engineers continue to |> think inside the 208 volt box. They think it is an accepted norm (and it |> is so relative to the people they deal with: landlords and developers who |> can shield them from the real problems of residents). So they don't even |> think about it. They just whack out a variation of the same old same old |> and people are then stuck with no improvement and have to accept it. | | | They do it because it works reliably, and at a reasonable cost. It | really isn't up to you, and there is no valid need for any 240 VAC for | anything the owner doesn't supply.
As long as the landlord supplies correct voltage appliances for whatever is supplied, all is well. Sadly, that is not the case quite often.
Reply to
phil-news-nospam
You were ripped off. Find an honest business to buy from.
Reply to
Michael A. Terrell
Why should they? Early TV stations had the studio at the transmitter site, and 120 VAC was readily available. In this case, a transmitter built in 1952 was moved to a new site to build a low power TV station in the mid '80s. The "Studio" was in a house 50 feet away. The "Studio" had 120/240 single phase service. the transmitter building didn't.
What kind of company continues to use the wrong compressor?
When they buy in quantity, they pay the same price for either version.
Then the judges are crooked.
One of the county's largest group of condos is a few miles from here. It is so big that some contractors do nothing but work to build new units, and maintain existing units. It is called, "The Villages"
Then the property isn't up to minumum housing codes, and can not legally be leaased or rented.
Reply to
Michael A. Terrell
| snipped-for-privacy@ipal.net wrote: |> |> |> |> | charles wrote: |> |> |> |> Power is a function of the voltage squared. So a 3kW heater at 240v |> |> becomes 2.25kW at 208v. It may not be significant if it's used for storage |> |> heating but as an instantaneous heater it would matter. |> | |> | |> | Gee thanks for that lesson. I've know and used it since the '50s. |> | If you need that extra bit of heat, you can buy the proper heating |> | element. Not at the over the counter type 'DIY' dumps, but at a real |> | plumbing supply house. |> |> Which means it is more expensive. And in many cases they have to special |> order it. I've already experienced the special order cost case with a |> 208 volts single phase motor (it was twice as much as a 240 volt motor of |> the same HP and mounting). | | You were ripped off. Find an honest business to buy from. |
It was like $120 instead of $60. That's no big deal considering the costs of dealing with A/C system failures, and having to shut down equipment to avoid over heating. The big hassle was it took 4 weeks to get that motor. Three 240 volt motors at $60 apiece burned up in the mean time.
Reply to
phil-news-nospam
Three transformers can't cost more than a three-phase transformer, or they'd do it for the 90% of the poles in existence now.
I wonder why? Could it be because there isn't a reason?
Ok, there was confusion on that point. Metering with a current transformer would seem to have calibration problems. They really need to meter power, not current.
It *CERTAINLY* is. Look at the voltages on the top of those pigs. It is *EXACTLY* what you describe as "six star". We generally look at it as three Edison 240V circuits, but it is *exactly* what you describe (six 120V circuits - each 60degrees from the next.
Look again (open your eyes this time). You're not seeing the forest for the trees. It *IS* on top of 90% of the poles in the country. The other 10% are single phase only, generally found only in rural areas.
Screws aren't expensive. The wires are there. It exists, though perhaps a bit different that you describe mechanically.
Really.
Huh? What are you blabbering about?
Get it through your head, IT'S THE SAME DAMNED THING. When you split the three phase ("wye" or delta) into three 240V Edison circuits you've just made your "six star". That's done on 90% of the poles in the country. As I said above, the other 10% are rural single-phase only circuits.
Good grief Phil, the CT transformer gives you 120V from the A-phase and it's mirror, 120V A'. Three of those gives you your "six-star".
The CT transformers on every damned pole in town. Man, you're thick.
Does it matter? The secondaries are the same phase as the primaries.
Think for a moment.
DAMN, you're thick!
You have three phases, each supplying a 240V Edison circuit. Connect the dotted lines...
I *KNOW* that.
You are master of the irrelevant, Phil.
A-HA! He does get it! Now look at the voltages on those secondaries; your "six-star".
Phil, I'm not the one who is "mixed up" here.
Totally irrelevant drivel.
Reply to
krw

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