280V motor on 230V circuit


Yep, their called Super Conducting Transformers, and they have been around the LABS, for about 15 years now. Only one BIG problem with them. They only work at 20 Degrees Kevin or lower in temperature.
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Of course not:-) These are approximate figures (like the 21 kV 10 kA alternator, which in fact is 9823 A 21200 volts or whatever). But the efficiency of large transformers or transmission lines, when they operate at optimum is 99%.
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<snip>

You're confusing two uses of the term 'regulation'. Tap changers and voltage regulators actively sense the terminal voltage and adjust 'something' to maintain the voltage within some design limit. That's a 'regulator' and provides 'regulation' of the sensed voltage.
But 'regulation' also is a term used to describe the inherent voltage drop in some devices. For example, if you review DC generators, you'll find that simple shunt-wound generators have fairly good 'regulation' and their output voltage only drops a few percent from no-load to full-load when supplied with a fixed field. A cumulatively-compound DC generator (which has a series field and a shunt field), can have a nearly flat voltage curve from no-load to full-load with just a fixed shunt excitation, or even have a voltage rise depending on the degree of compounding. (of course, an active voltage regulator can counteract whatever inherent regulation a machine may have)
In the case of simple fixed-tap transformers, the term 'regulation' can be used to describe how much the output terminal voltage changes from no-load to full-load if the primary voltage is held constant. This use is less than perfect as it is much better to use the transformer's impedance along with the load's power factor to get a more precise answer.
In the US, voltage regulation is accomplished with load-tap-changers, capacitor banks, and other 'voltage support services'. But just like in Europe, it is done at the substation or higher level and not done at the typical distribution transformer. There are exceptions for rural areas though where the line length of the primary leads to some issues.
daestrom P.S. In the US, a 'tap-changer' may be built for either for unloaded or loaded operation. The 'unloaded' type can not be stepped to another tap while there is load on the unit (although it can still be energized). It's switch contacts cannot interrupt load though, so if you try to move it while loaded, you can burn up the tap-changer. The classic 'load-tap-changer' is actually several switches that are controlled in a precise sequence to shift the load from one tap of the transformer to another while not interrupting the load current.
P.P.S. Load tap changers typically have a significant time-delay built into the controls so they do not 'hunt' or respond to short drops in voltage such as starting a large load. 15 seconds to several minutes is typical. So even with load-tap-changers, starting a single load that is a high percentage of the system capacity will *still* result in a voltage dip.
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<snip>
Sorry, should be '...contribute to whatever inherent regulation a machine may have'
daestrom
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I know that, but it was a temptation to post this:-)

A shame that Tesla won the infamous "battle" and we don't have DC:-() But then, we would be having a power plant at each neighborhood, instead of the 300 MW ones.

We have here capacitor banks, too, connected at the LV side of the substation, 15 kV line-to-line voltage. But just like in

Yeah, the ones we have here are automatic, live and even have a shaft for manual control.

I know, I know, my answer was a bit provocative:-) And of course there are DC regulators.... You're talking about DC generators;the one a 300 MW uses for excitation is 220 V, 1000 A DC and probably shunt field. I have seen here in some machine shops the old type welding generator, which is a 3 phase induction motor coupled to (usually) a compound field DC generator, which provides the welding current. The modern ones are, maybe, not larger than a shoe box and powered by a higher wattage 230 V 16 A receptacle. (Usual receptacles are 230 V 10 A;16 A for washing machines, dryers and the like).
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| A shame that Tesla won the infamous "battle" and we don't have DC:-() But | then, we would be having a power plant at each neighborhood, instead of the | 300 MW ones.
And the latter make easy terrorism targets, too.
| I know, I know, my answer was a bit provocative:-) And of course there are | DC regulators.... You're talking about DC generators;the one a 300 MW uses | for excitation is 220 V, 1000 A DC and probably shunt field. I have seen | here in some machine shops the old type welding generator, which is a 3 | phase induction motor coupled to (usually) a compound field DC generator, | which provides the welding current. The modern ones are, maybe, not larger | than a shoe box and powered by a higher wattage 230 V 16 A receptacle. | (Usual receptacles are 230 V 10 A;16 A for washing machines, dryers and the | like).
You don't use 400 V for anything heavy duty like an oven?
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And so does that 20 gallons of gasoline parked in front of your house. And that 500 gallons of diesel fuel in your basment. And that 20,000 or so gallons in the nearby gas station.
Yawn.
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danny burstein wrote:

http://www.triallogs.com/index.php?/component/option,com_smf/Itemid,43/action,dlattach/topic,66.0/attach,87 /
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Good that terrorists are brain-washed lunatics, and haven't access to incendiary rounds:-)

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snipped-for-privacy@ipal.net wrote:

In North America, 240V 50A is pretty standard for ovens, some are 40A, clothes dryers are 30A, most other stuff plugs into a 15A 120V receptacle.
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| | snipped-for-privacy@ipal.net wrote:
wrote: |> |> | A shame that Tesla won the infamous "battle" and we don't have DC:-() But |> | then, we would be having a power plant at each neighborhood, instead of the |> | 300 MW ones. |> |> And the latter make easy terrorism targets, too. |> |> |> | I know, I know, my answer was a bit provocative:-) And of course there are |> | DC regulators.... You're talking about DC generators;the one a 300 MW uses |> | for excitation is 220 V, 1000 A DC and probably shunt field. I have seen |> | here in some machine shops the old type welding generator, which is a 3 |> | phase induction motor coupled to (usually) a compound field DC generator, |> | which provides the welding current. The modern ones are, maybe, not larger |> | than a shoe box and powered by a higher wattage 230 V 16 A receptacle. |> | (Usual receptacles are 230 V 10 A;16 A for washing machines, dryers and the |> | like). |> |> You don't use 400 V for anything heavy duty like an oven? |> | | | In North America, 240V 50A is pretty standard for ovens, some are 40A, | clothes dryers are 30A, most other stuff plugs into a 15A 120V receptacle.
But we don't have an easy option for any higher voltage. In many parts of Europe, three phase 400/230V is delivered to homes. Then using 400V, either 2 lines or all 3 lines, is an option.
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     snipped-for-privacy@ipal.net writes:

Some parts of Europe do. You find ovens can be strapped to run from one or two phases, depending what's available on the premises. Some parts of Europe use 3-phase 400V domestic water heaters.
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I cross my fingers that terrorists get no electrical engineering degree:0

Yep. All ovens sold in EU are wired for 3 phase, 400 V with neutral (and earth, goes without saying). Just if you connect it on 1 phase (as usually) you use a bridge, and connect all L1-L2-L3 to the one and only hot. 230 V is powerful enough for almost everything in a house, only large airconditioners are 3 phase, and all industrial motors, even if they are 1HP:-) (

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|
| |> wrote: |> |> | A shame that Tesla won the infamous "battle" and we don't have DC:-() |> But |> | then, we would be having a power plant at each neighborhood, instead of |> the |> | 300 MW ones. |> |> And the latter make easy terrorism targets, too. |> | I cross my fingers that terrorists get no electrical engineering degree:0
I suspect quite many already have them. Many have degrees in a lot of other things like chemistry and physics. Some even have doctoral level degrees.
|> | I know, I know, my answer was a bit provocative:-) And of course there |> are |> | DC regulators.... You're talking about DC generators;the one a 300 MW |> uses |> | for excitation is 220 V, 1000 A DC and probably shunt field. I have seen |> | here in some machine shops the old type welding generator, which is a 3 |> | phase induction motor coupled to (usually) a compound field DC |> generator, |> | which provides the welding current. The modern ones are, maybe, not |> larger |> | than a shoe box and powered by a higher wattage 230 V 16 A receptacle. |> | (Usual receptacles are 230 V 10 A;16 A for washing machines, dryers and |> the |> | like). |> |> You don't use 400 V for anything heavy duty like an oven? |> | Yep. All ovens sold in EU are wired for 3 phase, 400 V with neutral (and | earth, goes without saying). Just if you connect it on 1 phase (as usually) | you use a bridge, and connect all L1-L2-L3 to the one and only hot. 230 V is | powerful enough for almost everything in a house, only large airconditioners | are 3 phase, and all industrial motors, even if they are 1HP:-) (
That means each element individually runs on 230 V and they just divided them up in three approximately equal sections, or use triple elements for each type of use.
How many things that have just ONE (large) element would have it available in both 230 V and 400 V versions?
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Professional washing machines. One of my very first days 'in the field' was to connect some of them. They have a large heating element, you can connect it single phase, or 3 phase, it just heats up faster (of course) when you connect it 3 phase. (they have a single phase motor, so it works also in pure 230 V).
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| Professional washing machines. One of my very first days 'in the field' was | to connect some of them. They have a large heating element, you can connect | it single phase, or 3 phase, it just heats up faster (of course) when you | connect it 3 phase. (they have a single phase motor, so it works also in | pure 230 V).
If it has 3 elements rated for 230 volts, with 3 separate connections that would be to three separate phase for a three phase feed, and all connected to the one phase for a single phase feed, then it should heat up at the same speed, while drawing three times the current (not accounting for the motor).
I don't know why it should heat up faster in three phase, or why you would say "of course" about it. I would think it would heat up faster if you took it over to London and hooked it up to a 240 volt supply.
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Maybe you connected with single phase just one element? The rest two remained unconnected? (3 230 volts elements, connected wye). I'm sure it heated up faster, in 3 phase connection.
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| |> wrote: |> |> | Professional washing machines. One of my very first days 'in the field' |> was |> | to connect some of them. They have a large heating element, you can |> connect |> | it single phase, or 3 phase, it just heats up faster (of course) when |> you |> | connect it 3 phase. (they have a single phase motor, so it works also in |> | pure 230 V). |> |> If it has 3 elements rated for 230 volts, with 3 separate connections that |> would be to three separate phase for a three phase feed, and all connected |> to the one phase for a single phase feed, then it should heat up at the |> same |> speed, while drawing three times the current (not accounting for the |> motor). |> |> I don't know why it should heat up faster in three phase, or why you would |> say "of course" about it. I would think it would heat up faster if you |> took |> it over to London and hooked it up to a 240 volt supply. |> | Maybe you connected with single phase just one element? The rest two | remained unconnected? (3 230 volts elements, connected wye). I'm sure it | heated up faster, in 3 phase connection.
You were the one who said "it just heats up faster (of course) when you connect it 3 phase."
I would disagree.
But the fact that you said "(of course)" seems you presume that to be the general case. Now your most recent comment at least acknowledges that if not all elements are connected, it won't heat up as fast.
In the simple case, each of 3 elements is individually wired, so you have a total of 6 leads. When connecting to three phase, one lead of each is connected to neutral, and each of the other leads is connected to separate phases. When connecting to single phase, they are all wired in parallel. Both cases always involve one of the leads from each element connected to neutral, so those 3 leads can be pre-connected together. So you could have just 4 leads. The common neutral lead needs to be rated for all the current together for it to be rated properly for single phase.
It should apply the same voltage (230V) to each element, and they should each draw the same current. How would you believe this would be slower to heat?
If the 3 elements were wired _internally_ in star without a neutral lead, it would still work fine on three phase as long as all elements were equal impedance. But on single phase, you could only activate 2 of the elements, and that would be 2 in series fed with 230 volts. You'd only get 1/6 the power that way.
Are you assuming the elements would be wired that way? That would clearly NOT be intended for single phase connection.
The 3 elements could be wired _internally_ in delta. In this case, these would have to be 400V elements. Connecting 2 leads to 230 volts would still give you only 1/6 the power (but more evenly distributed in this case).
So what is the situation that makes _you_ believe that 3 elements connected to single phase _will_ draw less power to heat the water than when connected to three phase?
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I have no idea, we didn't even open up the washing machines as they were under guarantee. I know that the landlady's electrician connected the wms single phase, and I connected (in the distr.box) all 3 phases. I suppose it has 3 elements connected wye, and single phase is 1 element, plus motor and automation.
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<snip>

Thing about DC generators used for welding, they are often *differentially* compounded, whereas those used for conventional power production are *cummulatively* compounded.
For power production, the series winding is arranged so that additional load will add MMF to the shunt field and help to compensate for the various internal factors causing a voltage drop.
But for welding, you don't want a constant voltage so much as a constant current. By using a differentially connected series winding, any increase in current in the series winding opposes the shunt winding, rapidly dropping the terminal voltage. So with no arc, the shunt winding gives you a nice, fairly high voltage to strike an arc, and as soon as you do, the voltage drops to whatever level is needed to maintain a specific current. Tap settings allow the welder to adjust what amount of current he gets so he can adjust for different welding. Often the 'course' adjustments are done with different taps to the series winding, and a final 'fine' adjustment is done with a lower-wattage rheostat controlling the exact amount of shunt-field current.
DC machines are often under-appreciated :-) (not to mention that some of this technology is older than either one of us and probably older than both of us put together)
daestrom
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