280V motor on 230V circuit

wrote: |
| |> |> wrote: |> |> |> |>> There are two different flavors of 220/230/240 volts. Some places
|> |>> have a |> |>> simple system with one wire hot and one wire grounded. Other |> |>> places have |> |>> a split system where the voltage is split in half to get |> |>> 110/115/120 volts |> |>> relative to ground, by adding a additional "middle" conductor that |> |>> is the |> |>> grounded one. |> |> |> |> Sonny, you need to LEARN the difference between Ground and |> |> Neutral...... |> |> before you spout any further BS....... |> | |> | What he wrote looks reasonable to me in terms of ground and neutral. |> | Neutral is the grounded conductor where I live. He does not say to |> | use a ground as a neutral, if that's what you're getting at. I can |> | only guess that that may be what you're getting at, you haven't really |> | said. |> |> He might be one of those "knows just enough to be really dangerous" people |> on the net. I didn't even mention "neutral". My intent was to explain it |> in a simpler way for someone to just understand the basic difference. The |> term "middle" was to convey a little more information than "neutral" would | <SNIP> | | Well, I understood what he meant, but maybe I took it the wrong way. When he | said middle conudctor I was thinking the center lug on the transformer which | is grounded and used as the neutral.
That is what I meant when I said middle conductor. I intentionally avoided calling it neutral for the person I was responding to. I did quote it to make it clear (but this apparently was not clear enough for at least one person) for others that I was using some other term.
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Nope. LV (low voltage)230-V in Europe is just sufficient for 1 km distance. MV (medium voltage) 20 kV for 60 km. HV (high voltage) 150 kV for 220 km. EHV 400kV for 500 km with stability issues. 110 volt is so low you need a transformer outside each building....
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Learn the system before you criticize it.
It's not 110V, it's 240V, we simply split it with a grounded center tap which gives 120V between each side and neutral, or 240V between the sides.. There's no transformer per house, except rural applications. Generally 5-10 houses are on each transformer, sometimes more. The problem with long runs is that the voltage fluctuates substantially with large loads such as central air conditioning. Standard North American residential service is 200 Amps 240V, I gather this is quite a bit larger than typical European domestic stuff, so stretching it over 1km distance would require prohibitively large cables or suffer from wide voltage swings. Makes more sense to run 7200V down the street and locate a smallish transformer near every half dozen houses.
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I'm perfectly aware of this, only in theory, though, as I've never been in USA. I have worked, though in the decommisioned US base in Gournes, really impressive your distribution systems:-) And in Europe we have 400 V (3 phase) line to line voltage. It's 230 line to earth. Large motors and conditioners use 3 phase. Normal residence is 40 A 230 V single phase, or for energy hogs 400 V 3 X 40 A 3 phase..

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Residential power in Sweden is 400V 3 phase, main fuses normally 25A or lower.
Room outlets are wired with one phase, neutral and ground to get 230V.
There is a smallish transformer station in the neighborhood which probably powers two entire blocks. I would guess somewhere around 20-30 houses.
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Absolutely the same here, in Greece we are using only Schuko sockets, from german Schutzkontakt, security contact. There is a larger substation, maybe 2-3 for a city (in Iraklion we have 3, 180,000 residents) that steps down from the transmission voltage, 150 kV down to primary distribution voltage, 15 kV that is the distributed with cables buried in earth. Our local power station has units with 15 kV (older) and newer with 6.6 kV alternators, all is stepped up to 150 kV even for the ~15 km to Iraklion. In capitals, like Athens, electricity comes at 400 kV, is stepped down to 150 kV for secondary transmission, again goes to the areas af the city with underground cables, stepped down to 15 kV locally, and then distributed again (the main generation facilities are in Kozani, West Macedonia, and they burn brown coal. Typical size of a unit is 300 MW, voltage 21 kV and current 10 kA which is stepped up to 400 kV, 400 A line current for transmission to Athens and Thessaloniki).
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Similar in UK.
In most European countries, there's a single phase current limit, above which you have to take a 3-phase supply. In the UK, that's 100A, so it's not very common to have a 3-phase supply although you can ask for one if you want a 3-phase supply. In some other European countries, the single phase limit is as low as 20A, so just about everyone has a 3-phase supply.
Residential substation transformers (11kV down to 230/400) are usually 1MVA, feeding a number of streets. A substation may have more than one transformer in some cases (although they usually only start out with one). Obviously, smaller transformers are used where there aren't so many houses, and these are sometimes pole mounted if the wiring is overhead.
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or, as in the case of the transformer that feeds my house, pole mounted in field with the output cables going underground immediately.
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It's the regulation at 120V which people notice. If you want to call it a 240V supply, then you need to call EU supplies 400V or 415V. That's equally misleading.

The transformers are small in comparison, which gives poor regulation in comparison (and as I said before, it's the regulation at 120V which is the primary concern -- regulation of 240V across 2 hots doesn't matter much for typical US 240V loads).
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Regardless, the regulation is very good. I monitored mine for a while and never saw it dip below 118V or go above 122V, most of the time it was just about spot on 120V. A friend in the UK was doing the same on his and it went as low as 224V and as high as 246V. We've done a lot of comparing and have agreed that neither system is inherently better or worse than the other, both have advantages and disadvantages.
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|> |> It's not 110V, it's 240V, we simply split it with a grounded center tap |> which gives 120V between each side and neutral, or 240V between the sides.. | | It's the regulation at 120V which people notice. | If you want to call it a 240V supply, then you | need to call EU supplies 400V or 415V. That's | equally misleading.
The effect of loading and how it affects voltage depends on how well balanced the TWO 120 volts phases are. If they are in balance, then the effect of the loading on the voltage works as if you were considering the voltage at 240 volts.
If you get a three phase supply, and keep it balanced with the single phase line to neutral loads, then the voltage regulation is going to be just like you had loaded it with line-to-line loads, 208 volts in North America and 400 volts in Europe.
If your neighborhood transformer is three phase, even if your home gets only one phase of it (at just 230 volts), you still get advantage because other homes will be distributed over other phases to keep it in balance.
But if you are comparing a single phase system, North American 120/240 with three wires, vs. European 230 with two wires, it works out to be about the same. The difference is we pay more for the extra wire, but we have a lower line to ground shock risk (which isn't really much of an issue anymore with improvements in safety in various ways such as GFI/RCD protection, better rules on installations, etc).
So if you moved from Europe where you had 400/230 volts three phase in your home, and came to North American and discovered we really had 480/277 volts three phase, would that trouble you (assuming all appliances were designed for that)?
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writes:

The regulation, at least in Europe, is done at 150/15 kV substations and at the HV side of the transformers, thus at 150 kV. Typical current for 2 x 25 MVA transformers is 150 A, 150 kV and of course secondary at 15 kV, 1500 A. The regulation is done automatically with tap changers, live. The local transformers at your neighborhood are fixed tap, 15 kV (they intend to change everything to 20 kV).
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I'm referring to the transformer regulation (and also the LV supply cable voltage drop) response to load changes. E.g. if I switch on my 10kW shower, that's a 0.1% change against the max load of my 1MVA substation transformer and therefore makes no perceivable difference to the voltage in my house. If I were to try that on a US 50kVA transformer, that load is going to trigger a change of 20% of the transformer regulation, which is much more significant and would certainly be visible as a brightness change in light bulbs.
Having lived in both countries, I would say it's pretty much expected in the US that lights dim even with quite moderate loads coming on, whereas it's rare in the UK (generally only in rural areas with long supply lines). There are many contributory factors to this difference, but the 120V verses 240V (or if you must, 240V verses 415V) is ultimately the underpinning reason.
Automatic tap changing in the HV network is completely invisible to the residential consumer, as indeed it should be.
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| I'm referring to the transformer regulation (and also the LV | supply cable voltage drop) response to load changes. E.g. if | I switch on my 10kW shower, that's a 0.1% change against the | max load of my 1MVA substation transformer and therefore | makes no perceivable difference to the voltage in my house. | If I were to try that on a US 50kVA transformer, that load | is going to trigger a change of 20% of the transformer | regulation, which is much more significant and would | certainly be visible as a brightness change in light bulbs.
What is the available fault current in these situations?
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wrote:
| The central air kicks on without my lights dimming, and I am in North | Central Florica.
I bet it's on its own branch circuit, too.
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snipped-for-privacy@ipal.net wrote:

Of course it is, that's the only legal way to do it.
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snipped-for-privacy@ipal.net wrote:

So what? The meter is on a pole on one side of the driveway ( two feet from the property line, because Progress Energy does not allow drops to cross a driveway anymore.), and an outdoor breaker box is on the remaining four foot stump of the old pole on the other side of the paved drive, about 40 feet away. The 60 A breaker for the AC is in that box, along with the 100 A main breaker that is used as a disconnect for the house. That box is over 125 feet from the pole pig, on a 150 A service. That box also feeds another underground line to the laundry building,, and well pump. The main breaker box for the house is another 20 feet from the outdoor box. Now, tell me how it can have no effect on the line voltage. I still see very little flickering, usually only on hot summer days when everyone in the subdivision is using the AC and their kitchen stoves at the same time. That is usually followed by a blown 60 A fuse in the 7200 volt line, feeding my street.
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wrote: | snipped-for-privacy@ipal.net wrote: |>
wrote: |> |> | The central air kicks on without my lights dimming, and I am in North |> | Central Florica. |> |> I bet it's on its own branch circuit, too. | | | So what? The meter is on a pole on one side of the driveway ( two | feet from the property line, because Progress Energy does not allow | drops to cross a driveway anymore.), and an outdoor breaker box is on | the remaining four foot stump of the old pole on the other side of the | paved drive, about 40 feet away. The 60 A breaker for the AC is in that | box, along with the 100 A main breaker that is used as a disconnect for | the house. That box is over 125 feet from the pole pig, on a 150 A | service. That box also feeds another underground line to the laundry | building,, and well pump. The main breaker box for the house is another | 20 feet from the outdoor box. Now, tell me how it can have no effect on | the line voltage. I still see very little flickering, usually only on | hot summer days when everyone in the subdivision is using the AC and | their kitchen stoves at the same time. That is usually followed by a | blown 60 A fuse in the 7200 volt line, feeding my street.
If it were not on its own branch circuit, that would (in addition to being a code violation) more likely cause other stuff (whatever else is on the same circuit) to experience dimming. The fact that it is onis own branch circuit doesn't mean there isn't a big voltage drop. But only the A/C would be getting it, and it wouldn't matter (much).
It can have no (or very little that cannot be noticed) effect on the line voltage because you have good wiring and the transformer has a high enough capacity and low enough impedance. This is stuff you know.
Blowing a 60 amp fuse at 7200 volts is not a small neighborhood.
I can understand them not wanting to go overheard over a driveway. RVs can be a fun place for kids to climb on (even if terribly unsafe). Or they can catch fire (I've seen that happen and it _was_ a case of a service drop over a driveway that faulted when the insulation melted off).
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snipped-for-privacy@ipal.net wrote:

48 lots, 47 with homes. That gives 7200*60/240 or 1800 A @ 240 V for 47 homes gives an average 38.29 A per home which is the reason that fuse can blow more than once a week, along with it's explosive discharge that sounds like a shotgun every time it blows.

At one time there were two meters on the property, because the original owner had a blacksmith shop in the 1200 Sq Ft garage.
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wrote: | snipped-for-privacy@ipal.net wrote: |>
wrote:
|> |> |> |> In alt.engineering.electrical Michael A. Terrell
|> |> |> |> | The central air kicks on without my lights dimming, and I am in North |> |> | Central Florica. |> |> |> |> I bet it's on its own branch circuit, too. |> | |> | |> | So what? The meter is on a pole on one side of the driveway ( two |> | feet from the property line, because Progress Energy does not allow |> | drops to cross a driveway anymore.), and an outdoor breaker box is on |> | the remaining four foot stump of the old pole on the other side of the |> | paved drive, about 40 feet away. The 60 A breaker for the AC is in that |> | box, along with the 100 A main breaker that is used as a disconnect for |> | the house. That box is over 125 feet from the pole pig, on a 150 A |> | service. That box also feeds another underground line to the laundry |> | building,, and well pump. The main breaker box for the house is another |> | 20 feet from the outdoor box. Now, tell me how it can have no effect on |> | the line voltage. I still see very little flickering, usually only on |> | hot summer days when everyone in the subdivision is using the AC and |> | their kitchen stoves at the same time. That is usually followed by a |> | blown 60 A fuse in the 7200 volt line, feeding my street. |> |> If it were not on its own branch circuit, that would (in addition to being |> a code violation) more likely cause other stuff (whatever else is on the |> same circuit) to experience dimming. The fact that it is onis own branch |> circuit doesn't mean there isn't a big voltage drop. But only the A/C would |> be getting it, and it wouldn't matter (much). |> |> It can have no (or very little that cannot be noticed) effect on the line |> voltage because you have good wiring and the transformer has a high enough |> capacity and low enough impedance. This is stuff you know. |> |> Blowing a 60 amp fuse at 7200 volts is not a small neighborhood. | | | 48 lots, 47 with homes. That gives 7200*60/240 or 1800 A @ 240 V for | 47 homes gives an average 38.29 A per home which is the reason that fuse | can blow more than once a week, along with it's explosive discharge that | sounds like a shotgun every time it blows.
Yup, big neighborhood. It wouldn't take much after 47 home central A/C's are running to go over the fuse rating. Any guess what the curve on that fuse is? E.g. how long can you go at 105%? 125%?
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