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Mains wiring question: Sizing buck-boost transformer?

Started by Gary Walters March 29, 2013
John Larkin wrote:
> On 31 Mar 2013 05:27:30 GMT, Jasen Betts <jasen@xnet.co.nz> wrote: > > >>On 2013-03-31, bloggs.fredbloggs.fred@gmail.com <bloggs.fredbloggs.fred@gmail.com> wrote: >> >>>On Saturday, March 30, 2013 9:50:17 PM UTC-4, Sylvia Else wrote: >>> >>> >>>>There are various takes on exactly what the OP was concerned about. My >>>> >>>>take was that he was concerned about how connecting a conventional >>>> >>>>transformed in an auto-transormer configuration can manage to increase >>>> >>>>its power rating. >>>> >>> >>>The answer is it doesn't increase the power rating of the >>>transformer. Analysis is what tells you the required transformer power >>>handling capability in the buck/boost configurations a lot more than >>>any fundamental physics. Maybe take it up a notch and declare a N:1 >>>stepdown xfrmr can be used in buck/boost circuits with loading up to >>>Nx KVA rating of the transformer. >> >>A 1kVA 1:1 transformer can be used as a 2kVA stepdown >>auto-transformer. > > > Schematic? > >
Yeah, Me too... I want to see that. That would be a new trick for me to add to my bag.. Jamie
On Sun, 31 Mar 2013 08:10:16 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com
wrote:

>On Sunday, March 31, 2013 10:59:13 AM UTC-4, John Larkin wrote: > >> >> Schematic? >> > >A 1:1 buck delivers 0 KVA to the load :-) He must be talking about using the center tap of secondary for 2:1.
Right, it works if you put the windings in series to make an autotransformer, 2:1 voltage ratio, but that's not a 1:1 buck, to play with words. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Sun, 31 Mar 2013 10:08:21 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Sun, 31 Mar 2013 08:10:16 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com >wrote: > >>On Sunday, March 31, 2013 10:59:13 AM UTC-4, John Larkin wrote: >> >>> >>> Schematic? >>> >> >>A 1:1 buck delivers 0 KVA to the load :-) He must be talking about using the center tap of secondary for 2:1. > >Right, it works if you put the windings in series
"Series complimentary".
> to make an autotransformer, >2:1 voltage ratio, but that's not a 1:1 buck, to play with words.
There is a proper glossary or terms for this, but few have landed on target in all respects as yet.
On Sun, 31 Mar 2013 10:18:48 -0700, DecadentLinuxUserNumeroUno
<DLU1@DecadentLinuxUser.org> wrote:

>On Sun, 31 Mar 2013 10:08:21 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Sun, 31 Mar 2013 08:10:16 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com >>wrote: >> >>>On Sunday, March 31, 2013 10:59:13 AM UTC-4, John Larkin wrote: >>> >>>> >>>> Schematic? >>>> >>> >>>A 1:1 buck delivers 0 KVA to the load :-) He must be talking about using the center tap of secondary for 2:1. >> >>Right, it works if you put the windings in series > > "Series complimentary". > >> to make an autotransformer, >>2:1 voltage ratio, but that's not a 1:1 buck, to play with words. > > There is a proper glossary or terms for this, but few have landed on >target in all respects as yet.
Transformers do what they do, and don't care much about words. Many transformers don't even speak English. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Sun, 31 Mar 2013 10:21:55 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Sun, 31 Mar 2013 10:18:48 -0700, DecadentLinuxUserNumeroUno ><DLU1@DecadentLinuxUser.org> wrote: > >>On Sun, 31 Mar 2013 10:08:21 -0700, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Sun, 31 Mar 2013 08:10:16 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com >>>wrote: >>> >>>>On Sunday, March 31, 2013 10:59:13 AM UTC-4, John Larkin wrote: >>>> >>>>> >>>>> Schematic? >>>>> >>>> >>>>A 1:1 buck delivers 0 KVA to the load :-) He must be talking about using the center tap of secondary for 2:1. >>> >>>Right, it works if you put the windings in series >> >> "Series complimentary". >> >>> to make an autotransformer, >>>2:1 voltage ratio, but that's not a 1:1 buck, to play with words. >> >> There is a proper glossary or terms for this, but few have landed on >>target in all respects as yet. > >Transformers do what they do, and don't care much about words. Many transformers >don't even speak English.
Yeah? Try wiring it "in series' with the wrong starting lead first. There are discreet series inductors, and there are series inductors tied together within the same magnetic field. They DO care about *those* words, turkey.
On Sun, 31 Mar 2013 10:39:02 -0700, DecadentLinuxUserNumeroUno
<DLU1@DecadentLinuxUser.org> wrote:

>On Sun, 31 Mar 2013 10:21:55 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Sun, 31 Mar 2013 10:18:48 -0700, DecadentLinuxUserNumeroUno >><DLU1@DecadentLinuxUser.org> wrote: >> >>>On Sun, 31 Mar 2013 10:08:21 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Sun, 31 Mar 2013 08:10:16 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com >>>>wrote: >>>> >>>>>On Sunday, March 31, 2013 10:59:13 AM UTC-4, John Larkin wrote: >>>>> >>>>>> >>>>>> Schematic? >>>>>> >>>>> >>>>>A 1:1 buck delivers 0 KVA to the load :-) He must be talking about using the center tap of secondary for 2:1. >>>> >>>>Right, it works if you put the windings in series >>> >>> "Series complimentary". >>> >>>> to make an autotransformer, >>>>2:1 voltage ratio, but that's not a 1:1 buck, to play with words. >>> >>> There is a proper glossary or terms for this, but few have landed on >>>target in all respects as yet. >> >>Transformers do what they do, and don't care much about words. Many transformers >>don't even speak English. > > > Yeah? Try wiring it "in series' with the wrong starting lead first.
That can be done, depending on what you mean by "wrong." Schematics, with notes and polarity dots, are a better way to convey things like this. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Sun, 31 Mar 2013 10:58:15 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Sun, 31 Mar 2013 10:39:02 -0700, DecadentLinuxUserNumeroUno ><DLU1@DecadentLinuxUser.org> wrote: > >>On Sun, 31 Mar 2013 10:21:55 -0700, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Sun, 31 Mar 2013 10:18:48 -0700, DecadentLinuxUserNumeroUno >>><DLU1@DecadentLinuxUser.org> wrote: >>> >>>>On Sun, 31 Mar 2013 10:08:21 -0700, John Larkin >>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Sun, 31 Mar 2013 08:10:16 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com >>>>>wrote: >>>>> >>>>>>On Sunday, March 31, 2013 10:59:13 AM UTC-4, John Larkin wrote: >>>>>> >>>>>>> >>>>>>> Schematic? >>>>>>> >>>>>> >>>>>>A 1:1 buck delivers 0 KVA to the load :-) He must be talking about using the center tap of secondary for 2:1. >>>>> >>>>>Right, it works if you put the windings in series >>>> >>>> "Series complimentary". >>>> >>>>> to make an autotransformer, >>>>>2:1 voltage ratio, but that's not a 1:1 buck, to play with words. >>>> >>>> There is a proper glossary or terms for this, but few have landed on >>>>target in all respects as yet. >>> >>>Transformers do what they do, and don't care much about words. Many transformers >>>don't even speak English. >> >> >> Yeah? Try wiring it "in series' with the wrong starting lead first. > >That can be done, depending on what you mean by "wrong." > >Schematics, with notes and polarity dots, are a better way to convey things like >this.
In transformer speak: "series complimentary" for "auto-transformer boost configuration". What your opinion of being "better" hardly has any meaning when an experienced electrician is in the field and needs to have such a thing "conveyed" over an audible phone. "These days" such a schematic would be easily available online. and is. And you don't need the notes if the winding start indicators (dots) are there. And they are also ALWAYS supposed to appear on the physical device as well.
On 2013-03-31, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
> On 31 Mar 2013 05:27:30 GMT, Jasen Betts <jasen@xnet.co.nz> wrote: > >>On 2013-03-31, bloggs.fredbloggs.fred@gmail.com <bloggs.fredbloggs.fred@gmail.com> wrote: >>> On Saturday, March 30, 2013 9:50:17 PM UTC-4, Sylvia Else wrote: >>> >>>> There are various takes on exactly what the OP was concerned about. My >>>> >>>> take was that he was concerned about how connecting a conventional >>>> >>>> transformed in an auto-transormer configuration can manage to increase >>>> >>>> its power rating. >>>> >>> >>> The answer is it doesn't increase the power rating of the >>> transformer. Analysis is what tells you the required transformer power >>> handling capability in the buck/boost configurations a lot more than >>> any fundamental physics. Maybe take it up a notch and declare a N:1 >>> stepdown xfrmr can be used in buck/boost circuits with loading up to >>> Nx KVA rating of the transformer. >> >>A 1kVA 1:1 transformer can be used as a 2kVA stepdown >>auto-transformer. > > Schematic? >
eg: take a isolating transformer and put the secondary in series with the primary, doubles (or halves) the voltage and can still handle full current T1: 1KVA 120V:120V ___________ | | | * | ____|___ ||| ___| _)|||(_ _)|||(_ 120V _)|||(_ 16&#8532;A _)|||(_ _)|||(_ ________)|||(___ | ||| | * 240V | 8&#8531;A |___________ * indicates start of winding. As Phil Allison pointed out this only works if you run the windings at their design voltage. As with any transformer if you run it under voltage you get less VA. -- &#9858;&#9859; 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
"John Larkin"
 Jasen Betts
> >>A 1kVA 1:1 transformer can be used as a 2kVA stepdown >>auto-transformer. > > Schematic? >
** Huh ? It's so obvious. Primary and secondary in series ( in phase) and the centre is the output. Supply voltage can now be doubled while the current in each winding is the same. So a 1kVA 120:120 iso makes a 2kVA 240:120 auto step-down. ... Phil
Phil Allison wrote:

> "John Larkin" > Jasen Betts > >>>A 1kVA 1:1 transformer can be used as a 2kVA stepdown >>>auto-transformer. >> >>Schematic? >> > > > ** Huh ? > > It's so obvious. > > Primary and secondary in series ( in phase) and the centre is the output. > > Supply voltage can now be doubled while the current in each winding is the > same. > > So a 1kVA 120:120 iso makes a 2kVA 240:120 auto step-down. > > > > ... Phil >
I must admit, I slip on that one.. +------------ | + | | | + 120AC OUT +---+. ,+---+----------------------+ )|( )|( + +' '+--+----------------------- | | IN/OUT 240AC | | | | +----------+ + IN 240AC For once Phil, I can say you tripped me up. Jamie