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280V motor on 230V circuit
-- 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.... -- Tzortzakakis Dimitrios major in electrical engineering mechanized infantry reservist hordad AT otenet DOT gr 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. |
280V motor on 230V circuit
jakdedert wrote:
Jamie wrote: hr(bob) wrote: On Apr 26, 6:14 pm, Jamie t wrote: Deodiaus wrote: I have a broken pool motor [magnetek y56y] which will cost a bundle to fix or repair. While doing a search on the web, I found the same model (really cheap) but wired for 280V, instead of the 230 V load that my wiring is supplies. Now, I was thinking of buying the cheap 280V model and installing it instead. Aside from rotating at a different speed and maybe some power inefficiencies, are there any other drawbacks of using the 280V model instead? are you sure it isn't 208 ? --http://webpages.charter.net/jamie_5" I'd be suspicious that the 280V was a misreading somehow of 230V. that sounds more plausible. I'm a little confused about a 230 volt circuit. In what part of the world does the utility supply 230v? Most countries are 230 Volts (50 Hz) with some exceptions, such as North America, parts of South America, Japan, and a few others. Nearly all of Europe is standardized on 230 Volts 50 Hz, although outlet/plug shapes still vary from country to country. |
280V motor on 230V circuit
Ο "James Sweet" έγραψε στο μήνυμα news:WMGTj.5083$ch1.2983@trndny09... -- 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.... -- Tzortzakakis Dimitrios major in electrical engineering mechanized infantry reservist hordad AT otenet DOT gr 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. 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.. 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. |
280V motor on 230V circuit
Europe.
I also noticed just last week that Malaysia and Singapore use 230V (@50Hz). |
280V motor on 230V circuit
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. |
280V motor on 230V circuit
? "Thomas Tornblom" ?????? ??? ?????? ... 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. 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). -- Tzortzakakis Dimitrios major in electrical engineering mechanized infantry reservist hordad AT otenet DOT gr |
280V motor on 230V circuit
In article ,
Thomas Tornblom writes: 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. 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. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
280V motor on 230V circuit
In article WMGTj.5083$ch1.2983@trndny09,
"James Sweet" writes: 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. 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. 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). -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
280V motor on 230V circuit
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). 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. |
280V motor on 230V circuit
In article ,
Andrew Gabriel wrote: In article , Thomas Tornblom writes: 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. 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. or, as in the case of the transformer that feeds my house, pole mounted in field with the output cables going underground immediately. -- From KT24 - in "Leafy Surrey" Using a RISC OS computer running v5.11 |
280V motor on 230V circuit
In alt.engineering.electrical Andrew Gabriel wrote:
| In article WMGTj.5083$ch1.2983@trndny09, | "James Sweet" writes: | | 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)? -- |WARNING: Due to extreme spam, I no longer see any articles originating from | | Google Groups. If you want your postings to be seen by more readers | | you will need to find a different place to post on Usenet. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
? "Andrew Gabriel" ?????? ??? ?????? ... In article WMGTj.5083$ch1.2983@trndny09, "James Sweet" writes: 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. 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. 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). 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). -- Tzortzakakis Dimitrios major in electrical engineering mechanized infantry reservist hordad AT otenet DOT gr |
280V motor on 230V circuit
In article ,
"Tzortzakakis Dimitrios" writes: ? "Andrew Gabriel" ?????? ??? ?????? ... In article WMGTj.5083$ch1.2983@trndny09, "James Sweet" writes: 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. 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. 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). 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). 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. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
280V motor on 230V circuit
In alt.engineering.electrical Andrew Gabriel wrote:
| 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? -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
Tzortzakakis Dimitrios wrote: 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). So they have developed 100% efficient transformers? -- http://improve-usenet.org/index.html Use any search engine other than Google till they stop polluting USENET with porn and junk commercial SPAM If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm |
280V motor on 230V circuit
Andrew Gabriel wrote: In article , "Tzortzakakis Dimitrios" writes: ? "Andrew Gabriel" ?????? ??? ?????? ... In article WMGTj.5083$ch1.2983@trndny09, "James Sweet" writes: 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. 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. 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). 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). 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. The central air kicks on without my lights dimming, and I am in North Central Florica. Automatic tap changing in the HV network is completely invisible to the residential consumer, as indeed it should be. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] -- http://improve-usenet.org/index.html Use any search engine other than Google till they stop polluting USENET with porn and junk commercial SPAM If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm |
280V motor on 230V circuit
The central air kicks on without my lights dimming, and I am in North Central Florica. Mine dim slightly for an instant when my 3 ton heat pump kicks in, it's only noticeable with the few incandescent lights left in the house though. The LRA on that thing is something like 90A. I think most of the drop must be in the 50' or so of 2/0 AL wire between the meter base and the transformer though as they don't seem to dim at all from any of the neighbors. |
280V motor on 230V circuit
In article ,
"Michael A. Terrell" wrote: So they have developed 100% efficient transformers? 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. |
280V motor on 230V circuit
In alt.engineering.electrical Michael A. Terrell 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. -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
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280V motor on 230V circuit
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280V motor on 230V circuit
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280V motor on 230V circuit
wrote:
In alt.engineering.electrical Michael A. Terrell wrote: | wrote: | | In alt.engineering.electrical Michael A. Terrell 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. 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. 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). At one time there were two meters on the property, because the original owner had a blacksmith shop in the 1200 Sq Ft garage. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
280V motor on 230V circuit
In alt.engineering.electrical Michael A. Terrell wrote:
| wrote: | | In alt.engineering.electrical Michael A. Terrell wrote: | | wrote: | | | | In alt.engineering.electrical Michael A. Terrell 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. | | | 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%? -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
? "Michael A. Terrell" ?????? ??? ?????? m... Tzortzakakis Dimitrios wrote: 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). So they have developed 100% efficient transformers? .net/ISP.htm 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%. -- Tzortzakakis Dimitrios major in electrical engineering mechanized infantry reservist hordad AT otenet DOT gr |
280V motor on 230V circuit
? "daestrom" ?????? ??? ?????? ... "Tzortzakakis Dimitrios" wrote in message ... ? "Andrew Gabriel" ?????? ??? ?????? ... snip 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). 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). 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. I know that, but it was a temptation to post this:-) 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) 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. 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'. We have here capacitor banks, too, connected at the LV side of the substation, 15 kV line-to-line voltage. 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. 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). -- Tzortzakakis Dimitrios major in electrical engineering mechanized infantry reservist hordad AT otenet DOT gr |
280V motor on 230V circuit
"daestrom" writes:
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. Are the load tap generators configured make-before-break? Break-before-make would mean a (very short) power outage every activation but make-before-break would mean a momentarily short-circuited winding and the break would involve interrupting a large short circuit current. Certainly modern ones likely use thyristors and zero crossing detectors. When I was a kid living in a rather rural area, there would be a pair of these on poles every few miles, connected open delta. (all transformer primaries were connected phase-phase then). |
280V motor on 230V circuit
In alt.engineering.electrical Tzortzakakis Dimitrios 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? -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
In writes:
In alt.engineering.electrical Tzortzakakis Dimitrios 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. 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. -- __________________________________________________ ___ Knowledge may be power, but communications is the key [to foil spammers, my address has been double rot-13 encoded] |
280V motor on 230V circuit
In alt.engineering.electrical Michael Moroney wrote:
| Are the load tap generators configured make-before-break? | Break-before-make would mean a (very short) power outage every activation | but make-before-break would mean a momentarily short-circuited winding and | the break would involve interrupting a large short circuit current. I wonder how much regulation could be managed through the use of variable leakage inductance in the transformer windings. | Certainly modern ones likely use thyristors and zero crossing detectors. With zero crossing detection, then the switching is not happening on all phases at the same time. -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
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280V motor on 230V circuit
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280V motor on 230V circuit
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280V motor on 230V circuit
In sci.electronics.repair jakdedert wrote:
I'm a little confused about a 230 volt circuit. In what part of the world does the utility supply 230v? Continental Europe used to have 220 volts (before that it was 127 volts in some places), the UK used to have 240 volts. Nowadays, the common voltage is 230 volts -10% +6%. -- Met vriendelijke groet, Maarten Bakker. |
280V motor on 230V circuit
danny burstein wrote:
And the latter make easy terrorism targets, too. 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. http://www.triallogs.com/index.php?/...6.0/attach,87/ |
280V motor on 230V circuit
wrote: In sci.electronics.repair jakdedert wrote: I'm a little confused about a 230 volt circuit. In what part of the world does the utility supply 230v? Continental Europe used to have 220 volts (before that it was 127 volts in some places), the UK used to have 240 volts. Nowadays, the common voltage is 230 volts -10% +6%. In other words, nothing has changed. They just wrote sloppier specs. -- http://improve-usenet.org/index.html Use any search engine other than Google till they stop polluting USENET with porn and junk commercial SPAM If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm |
280V motor on 230V circuit
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280V motor on 230V circuit
In alt.engineering.electrical daestrom wrote:
| | wrote in message | ... | In alt.engineering.electrical Michael Moroney | wrote: | | | Are the load tap generators configured make-before-break? | | Break-before-make would mean a (very short) power outage every | activation | | but make-before-break would mean a momentarily short-circuited winding | and | | the break would involve interrupting a large short circuit current. | | I wonder how much regulation could be managed through the use of variable | leakage inductance in the transformer windings. | | | I suppose you could, but increasing leakage inductance means you're | increasing losses aren't you? Just a percent or two on a unit rated for 250 | MVA can be too much to tolerate. Isn't it just inductance in series? Shouldn't that just be a phase shift as seen from the primary side? -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
280V motor on 230V circuit
---------------------------- "Michael Moroney" wrote in message ... "daestrom" writes: 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. Are the load tap generators configured make-before-break? Break-before-make would mean a (very short) power outage every activation but make-before-break would mean a momentarily short-circuited winding and the break would involve interrupting a large short circuit current. -------- Yes -you are shorting a part of the winding but the switching is a bit more complex than that so that short circuit currents are limited to reasonable values. It is a multistep operation with reactor switching. On-load tap changers are expensive and are generally limited to applications where this is absolutely needed (I have seen one where the tap changer was nearly as large as the transformer). -------------- Certainly modern ones likely use thyristors and zero crossing detectors. ------------- Possibly but probably not- I am out of date on this but I would expect that the old way of good switches plus reactors might still be the better way. It saves a lot of control wiring plus a lot of money to operate thyristors at 300KV and 500A or more and I doubt whether they would be cost effective or technically advantageous otherwise. -------------------------- When I was a kid living in a rather rural area, there would be a pair of these on poles every few miles, connected open delta. (all transformer primaries were connected phase-phase then). "on load tap changers"? Not likely. These were applied to transformers only where it was worth the effort. Definitely transformers in rural areas- typical pole pigs- would have to be de-energized as the tap changer is a manually operated switch inside the tank. Some larger transformers did have off-load but live changers operated from ground level. What you saw could have been somethng else altogether. Delta primaries as you indicate were around when you were a kid, would, in most areas mean that you are now a pensioner. I remember cases of conversion from delta to star for distribution primaries in small towns being done about 60 years ago and use of delta for transmission died much before that. -- Don Kelly remove the X to answer |
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