CA1181495A - Ferro-resonant-type transformer - Google Patents
Ferro-resonant-type transformerInfo
- Publication number
- CA1181495A CA1181495A CA000387580A CA387580A CA1181495A CA 1181495 A CA1181495 A CA 1181495A CA 000387580 A CA000387580 A CA 000387580A CA 387580 A CA387580 A CA 387580A CA 1181495 A CA1181495 A CA 1181495A
- Authority
- CA
- Canada
- Prior art keywords
- ferro
- resonant
- transformer
- secondary winding
- type transformer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
- G05F3/02—Regulating voltage or current
- G05F3/04—Regulating voltage or current wherein the variable is ac
- G05F3/06—Regulating voltage or current wherein the variable is ac using combinations of saturated and unsaturated inductive devices, e.g. combined with resonant circuit
Abstract
A FERRO-RESONANT-TYPE TRANSFORMER
Abstract of the Invention A transformer wound for ferro-resonant transformer response on a core of conventional transformer material and dimension. The principal secondary winding flux path sa-turates in both the external core legs of the transformer as well as the center core leg, and therefore has more losses than a traditionally constructed ferro-resonant transformer where only the center core leg saturates, but the difference in such losses is more than compensated for by the savings in construction, since conventional transformer materials and techniques are employed for manufacturing the trans-former disclosed herein.
Abstract of the Invention A transformer wound for ferro-resonant transformer response on a core of conventional transformer material and dimension. The principal secondary winding flux path sa-turates in both the external core legs of the transformer as well as the center core leg, and therefore has more losses than a traditionally constructed ferro-resonant transformer where only the center core leg saturates, but the difference in such losses is more than compensated for by the savings in construction, since conventional transformer materials and techniques are employed for manufacturing the trans-former disclosed herein.
Description
sACKGRou~D OF THE INVENTION
Field of_the Invention This invention pertains to a device known as a ferro-resonant trans:ormer and specifically to an improved struc-ture therefor.
Descriptlon of the Prior Art A ferro-resoilant transformer, sometirn-es referred to as "Sola" regulator, is a special type of transio.rmer that accepts an applied square wave voltage and, because of inherent properties of the transformer, furnishes a more si.nusoidal alternatiny current output. A capacitor is connected across the secondary of the transformer tuned near the resonant frequency of the ac to achieve this operating mode.
In a conv2ll-t:ional ferro-resonant transformer, the cores or legs of the transformer are comprised of laminations of a steel ]cnown-for its magnetic ef:Eiciency and referred to in the~ industry as "ferro-resonant steel". Steel grade M6 or better have he.retofore been thought to be necessary for obtaining fer.ro-resonarlt transformer operat:ion. Such stee can be made i.n very thinly laminated parts and result in very small los~-es due to eddy currents.
Now refe:rrin() to the magnetic operation of a prior ar-t ferro-resonant trallsformer, such a transformer traditionally includes windi.ncJs for both the primary and seconcl.lry ~ound about a center core or leg of ferro-resonant steel. The external legs of -~he transformer are likewise comprised of laminated ferro-resonant steel and the dimensions are such that the sum of t}-le cross-sectional dimension of the ex-terllal legs e~cc~eds the cross-sectional dimension oE the center leg to rccluce losses.
There are also more turns on the secondary winding -than on the primary win(3ing. In operation, the primary windin~
cloes not cause suificient flux density i~ the principal path through relateci core to cause sa-turation and, therefore, ]0 opexates in the lirlear mode. Mowever, the secondary windillg does cause suEficient flux density in the center l.eg of the core related to i-ts operation and therefore does not operate in a linear mocle. In fact, on the B-H curve (flux densi.ty-coercive force curve), operation is such tha-t a large coer-cive force is required for a small change of flux density and, hence, provicles good regulation properties. The ex-ternal legs, because o:E thei.x dimensional rela-tionship to the center le~, do not saturate. It has heretofore been be-lieved that i-t was necessary to avoid saturat:in~ thc e.~cter-nal le~s because to do so would create too many losses anclthereEore such a structure would be unsatisfactorily ilte f -:Eicien t .
Ilowever, it should be noted that ferro-resonarlt trans-former of the t:raditional desi~n described above ls an expensive structure to manufacture compared with a conven-tional transforlllel-. First, the steel is much more eY~pensi.ve.
Grade Ml9 is pe:rfec-tly acceptable for a conventional trans-former compared with Grade M6 for a ferro-resonant -transformer ~i Of traditional des;.~n. Next, a conventional transformer is ~8~
generally evenly dimensioned with respect to the flu~ paths of both the primary and secondary windings. That is, -the center core leg i5 usually dimensioned so that it is e~actly twice in cross~section to the sum of the cross-scction dimensions of the e~ternal legs. Bo-th these factors prevent the use of conventional transformer laminations for -the construction of a ferro-resonant transformer.
Further, it hcls no-t heen known how *o standardize Perro-resonant transformer construction so that -the same 1~ component parts can be assembled in nearly the same fashion for operation w:ith respeck to various input volta~es for providing the same rated volt-ampere rating for -the trans-former, Therefore, it is a feature of the present invention to provide an improved ferro-resonant-type transformer that cloes not employ ferro-resonant steel, but the less e~pensive steel employed in conventional transformersO
~ t is another Eeature of the present invention to provide an improvec~ Eerro-resonant-type trarls~ol.mer tl-lat employs core d:irnellsions common ~or conventional transformers.
It is stil:L another feature o.~ the present invention to provile an improvecl Eerro-resonallt-type transformer that is constructed in such a way that it is connectable to various input driver ci.rcuits, all parts being common to a conven-tional transformer.
~u~-,mar~ of -the Inventlon The invent:Lon embodiment disclosed shows a transformer core of a "T" configuration made of laminated steel commonly employed in conventional transformers. The external legs are each in an "L" configuration and are likewise made of laminated stecl commonly employed in conventional trans-:Eormers. The primal-y winding has fewer turns -than the secondary winding arld the secondary winding has a sufficient number oE turns to saturate the entire principal flux pa-th re:Lated to the secondary winding, including the center leg, the external legs and the shunts.
The windings are provided in layers for the primary so as to have connecti.ons for operating in connecti.on with an inverter connected to a battery or other de source ovcr a eol~on ranc3e o:E voltacJes. The secondary is also provided with eonvenient taps.
Thus, b:road:Ly, -the invention eontemplates a ferro-resonant-type transEorme.r whieh eomprises a laminatecl eenter leg and a pair of laminated external legs made of eonventional trans:Eormer steel, with the eross-sectlonal dimension of the center leg eclualling the sum of -the cross-seetional dimensions of the external legs. A
primary winding is wound about the eenter leg and has suEficient turns and resistance so as to operate within the linear ranye with respect to applied rated s~uare wave voltage. A secondary winding is wound about the center leg and spaced apart from the primary winding, with a magnetic shunt between the primary winding and the secondary winding. The secondary winding has sufficient turns and resistance so that the steel in the center leg underneath the secondary winding and the return flux path through the external legs and the shunt Elux satura-tes :Eor rated volt ampexes, therefore resulting in a non-s~uare wave output with good regu-la-tion and without excessive losses in ferro-resonant-type transformer action.
Brief Description of the ~
So that the manner in which the above-recited features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be under-stood in de-tail, more particular description of the inven-tion br.iefly summari2ed above may be had by reEerencc to the embod:iment thereo~ which is lllustrated in the appended drawings, whi.ch drawings form a par-t oE this specifica-tion.
It i5 to be noted~ however, tha-t the appended drawings illustrate only a preferred embodiment of the invention and `''.`' are therefore not to be considered limiting of its scope, ~or the inven-~ion may admit to other equally effective embodiments.
In the Drawings: -Fig. 1 is a plan view of a ferro-resonan-t--type -trans-former in accordance with the presen-t invention, also showing flux paths for both the primary winding and secondary wind-ing .
Fig. 2 is a top view of a transformer ~obbin as i-t is 1~ positioned wi-th respect to the legs of a transformer in accordance with -the present invention.
E'ig. 3 is a partial side view of a vertical cross-sec-tion of a ferro-resonant-type transformer in accordance with the present invention.
Fig. 4 is a schematic diagram of the primary winding for a ferro-resonant-type transformer in accordance with the presen-t invention when connected for operation with respect to a square wave input derived from a 30-volt dc source.
Fi~. 5 is a schematic diagram of the primary winding for a ferro-resonant-type transformer in accordance ~:ith the presen-t invention when connec-ted Eor operation wi-th respec-t to a s~uare wave input derived from a 60-volt dc source.
Fig. 6 is a schema-tic diagram of the primary winding Eo.r a Eerro-reson~n-t---type -transformer in accordance wi-th -the present invention when connected for operation with respec-t to a square wave input derived from a 120-volt dc source.
Fig. 7 is a schematic diagram of -the secondary winding for a ferro-resonant-type transformer connected -to a capa-citor -for resonant operation near the desired frequency of operation.
Fig. 8 is an overall schematic diagram of a ferro-resonant transformer in a typical connection configura-tion.
Deseription of Preferred Embodiment Now referring to the drawings, and first to Fig. 1, 2 and 3, it is typieal that a transformer employ a stack of laminated parts. The number of laminates is not so material as the dimension of the stack-. In a 1000 VA ferro-resonant-type transformer in accordance with the present invention it has been found convenient to provicle stacks of grade Ml9 steel laminates that is 3 3/4 inches high i.n depth dimension 10 for each the eenter leg and the -two external legs.
Width 12 of the center eore leg 11 is 1 1/2 inches and width 1~ of eaeh of the external legs lS and 17 is 3/4 inehes.
~lenee, the dimension in eross-seetion of the sum of the e~ternal legs is ec~ual to that of the eenter leg.
It is typical to have the primary winding and the seeondary winding of a conventional transformer wound on bobbins made of glastic, a non-magnetie combination of fib~r~las and plastic. For conventional transformers having eenter eore laminates 1-1/~ inches wide, -the stack is nor-mally 3 inches. Therefore, two bobbins are used to make one bobbin 16~ Split 18 shows where these two bobbin parts are joined.
Turns ~0 for the primary winding are shown in Fig. 3 Wound on bobbin 16. In a similar fashion -turns are wound on a separate bobbi.ll for the secondary windi.ng. The windings are sepclrated frorn each other by an air gap. Eor tl-e trans-formel. beiny de<,cri.bed, -the air gap between the center leg ancl external le~3 is 3/4 of an inch wide, as identi,fied by nwlleral 22. A shunt 24 fills most of the air g.lp/ w;dth dimc~nsion 26 being 0.660 of an inch. The depth dimension is 3 inclles and the height is 0.98 of an inch. The shunt is also made of laminated sections, the laminations bei.ncJ shown endwise in Fig. 3 for the shunt. A simi.lar .shun-t 28 is prov.ided in the opposite air gap. Pieces of "NO~EX"* fill up the remainder of the air gaps not occupied by the shunts.
The principal flux path for the primary windi.ng is shown in Fig. l as ~p and the principal path for the flux pa-th related to the secondary winding is shown in Fig. l as 0s It should be understood that complementary paths for both windings also pass through the other external leg in acldition to the l.eg illustrated. There is some flux :for both windirlgs that travel the entire core length, and thus also pass through the other winding from -the windi'ng creatin~ the :~: lu~
The secJmc~llt:s or the windings which overall. ma!ie up thc primary windi3ly just descri~ed are shown in Fiys. 4, 5 and . In Fig. ~, wind:iTIy 30A and 30B comprise the E:irst two .layers; windincJs 32A and 32B comprise the second two layers;
windings 3~A and 34B comprise the third two laye-s, and windinc3s 36A and 36B comprise the fourth two layers. Each layer set is sel:~arated by an insulatin~ layer of "NOME.X"* and the parallel connections are made as shown. Small driver windin~s 38 and 40 share the final layer. Each of the four * trade mark 8 windings comprise 46 turns of number 14 wire. The driver windings each have 5 turns of number 16 wire.
Fig. 5 shows a configuration wherein the same four windings 30, 32, 34 and 36 are used wi-thout the ccnter tap connections emp~oyed in Fig. 4. Fig. 6 shows a conficJura-tion wherein winciings 30 and 32 are connected in series and windings 34 and 36 are connected in series and the connec-tion bekween the two series connections provides a center tap for the ent:ire primary. Again, the driver windings are the same as for the Fig. 4 and Fig. 5 structures.
The secondary winding comprises 238 turns of number 12 wires and is wouncl to provide seven layers of 34 turns per layer. Taps are provided at the 72nd, 93rd and 162nd turns to provide 120-volt, 240-volt and 277-volt taps for a 400-volt overall secondary. Capacitor ~2 across the secondary at 39 microfarads tunes the secondary to a resonant fre-quency ~us-t off 60 Hz for successful ferro-resollant opera-tlo~l.
~ typical overall schematic diagram for the ferro-resonant-type transformer just described is shown in Fig. 8.
Such a~structure provides operation of the ~)rimary winding in the ]inear ranye and the secondary winding in a satisfactory saturated mode for variatlons 85 to 100 per-cent of the voltac~e inputs shown in Figs. 4, 5 and 6.
Regula-tion can be improved with a ]arger capacitor 42, but losscs do increase. Ilowever, with the values shown, al-though greater -than with prior art ferro-resonan-t trans-formers, the losses are not great.
~ regulation ratinc3 of 2-1/2 is a cor~lon design goal ~ " ,J _ g (volts in secondary times circulating current equals 2-1/2 times the VA rating for the primary). In this case, the circulating current is a little over 6 amperes for an overall regulation rating of 2.8, which is quite goodO
The output waveform includes some high harmonic dis-tortions which can be filtered out by appropriate components (not shown), if desired. Also, the output waveform can be further shaped to be more sinusoidal, if desired.
While a particular embodiment of the invention has been shown and described, i-t will be understood that the inven--tion is not limited thereto, since many modifications may be made and will become apparent to those skilled in the art.
Field of_the Invention This invention pertains to a device known as a ferro-resonant trans:ormer and specifically to an improved struc-ture therefor.
Descriptlon of the Prior Art A ferro-resoilant transformer, sometirn-es referred to as "Sola" regulator, is a special type of transio.rmer that accepts an applied square wave voltage and, because of inherent properties of the transformer, furnishes a more si.nusoidal alternatiny current output. A capacitor is connected across the secondary of the transformer tuned near the resonant frequency of the ac to achieve this operating mode.
In a conv2ll-t:ional ferro-resonant transformer, the cores or legs of the transformer are comprised of laminations of a steel ]cnown-for its magnetic ef:Eiciency and referred to in the~ industry as "ferro-resonant steel". Steel grade M6 or better have he.retofore been thought to be necessary for obtaining fer.ro-resonarlt transformer operat:ion. Such stee can be made i.n very thinly laminated parts and result in very small los~-es due to eddy currents.
Now refe:rrin() to the magnetic operation of a prior ar-t ferro-resonant trallsformer, such a transformer traditionally includes windi.ncJs for both the primary and seconcl.lry ~ound about a center core or leg of ferro-resonant steel. The external legs of -~he transformer are likewise comprised of laminated ferro-resonant steel and the dimensions are such that the sum of t}-le cross-sectional dimension of the ex-terllal legs e~cc~eds the cross-sectional dimension oE the center leg to rccluce losses.
There are also more turns on the secondary winding -than on the primary win(3ing. In operation, the primary windin~
cloes not cause suificient flux density i~ the principal path through relateci core to cause sa-turation and, therefore, ]0 opexates in the lirlear mode. Mowever, the secondary windillg does cause suEficient flux density in the center l.eg of the core related to i-ts operation and therefore does not operate in a linear mocle. In fact, on the B-H curve (flux densi.ty-coercive force curve), operation is such tha-t a large coer-cive force is required for a small change of flux density and, hence, provicles good regulation properties. The ex-ternal legs, because o:E thei.x dimensional rela-tionship to the center le~, do not saturate. It has heretofore been be-lieved that i-t was necessary to avoid saturat:in~ thc e.~cter-nal le~s because to do so would create too many losses anclthereEore such a structure would be unsatisfactorily ilte f -:Eicien t .
Ilowever, it should be noted that ferro-resonarlt trans-former of the t:raditional desi~n described above ls an expensive structure to manufacture compared with a conven-tional transforlllel-. First, the steel is much more eY~pensi.ve.
Grade Ml9 is pe:rfec-tly acceptable for a conventional trans-former compared with Grade M6 for a ferro-resonant -transformer ~i Of traditional des;.~n. Next, a conventional transformer is ~8~
generally evenly dimensioned with respect to the flu~ paths of both the primary and secondary windings. That is, -the center core leg i5 usually dimensioned so that it is e~actly twice in cross~section to the sum of the cross-scction dimensions of the e~ternal legs. Bo-th these factors prevent the use of conventional transformer laminations for -the construction of a ferro-resonant transformer.
Further, it hcls no-t heen known how *o standardize Perro-resonant transformer construction so that -the same 1~ component parts can be assembled in nearly the same fashion for operation w:ith respeck to various input volta~es for providing the same rated volt-ampere rating for -the trans-former, Therefore, it is a feature of the present invention to provide an improved ferro-resonant-type transformer that cloes not employ ferro-resonant steel, but the less e~pensive steel employed in conventional transformersO
~ t is another Eeature of the present invention to provide an improvec~ Eerro-resonant-type trarls~ol.mer tl-lat employs core d:irnellsions common ~or conventional transformers.
It is stil:L another feature o.~ the present invention to provile an improvecl Eerro-resonallt-type transformer that is constructed in such a way that it is connectable to various input driver ci.rcuits, all parts being common to a conven-tional transformer.
~u~-,mar~ of -the Inventlon The invent:Lon embodiment disclosed shows a transformer core of a "T" configuration made of laminated steel commonly employed in conventional transformers. The external legs are each in an "L" configuration and are likewise made of laminated stecl commonly employed in conventional trans-:Eormers. The primal-y winding has fewer turns -than the secondary winding arld the secondary winding has a sufficient number oE turns to saturate the entire principal flux pa-th re:Lated to the secondary winding, including the center leg, the external legs and the shunts.
The windings are provided in layers for the primary so as to have connecti.ons for operating in connecti.on with an inverter connected to a battery or other de source ovcr a eol~on ranc3e o:E voltacJes. The secondary is also provided with eonvenient taps.
Thus, b:road:Ly, -the invention eontemplates a ferro-resonant-type transEorme.r whieh eomprises a laminatecl eenter leg and a pair of laminated external legs made of eonventional trans:Eormer steel, with the eross-sectlonal dimension of the center leg eclualling the sum of -the cross-seetional dimensions of the external legs. A
primary winding is wound about the eenter leg and has suEficient turns and resistance so as to operate within the linear ranye with respect to applied rated s~uare wave voltage. A secondary winding is wound about the center leg and spaced apart from the primary winding, with a magnetic shunt between the primary winding and the secondary winding. The secondary winding has sufficient turns and resistance so that the steel in the center leg underneath the secondary winding and the return flux path through the external legs and the shunt Elux satura-tes :Eor rated volt ampexes, therefore resulting in a non-s~uare wave output with good regu-la-tion and without excessive losses in ferro-resonant-type transformer action.
Brief Description of the ~
So that the manner in which the above-recited features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be under-stood in de-tail, more particular description of the inven-tion br.iefly summari2ed above may be had by reEerencc to the embod:iment thereo~ which is lllustrated in the appended drawings, whi.ch drawings form a par-t oE this specifica-tion.
It i5 to be noted~ however, tha-t the appended drawings illustrate only a preferred embodiment of the invention and `''.`' are therefore not to be considered limiting of its scope, ~or the inven-~ion may admit to other equally effective embodiments.
In the Drawings: -Fig. 1 is a plan view of a ferro-resonan-t--type -trans-former in accordance with the presen-t invention, also showing flux paths for both the primary winding and secondary wind-ing .
Fig. 2 is a top view of a transformer ~obbin as i-t is 1~ positioned wi-th respect to the legs of a transformer in accordance with -the present invention.
E'ig. 3 is a partial side view of a vertical cross-sec-tion of a ferro-resonant-type transformer in accordance with the present invention.
Fig. 4 is a schematic diagram of the primary winding for a ferro-resonant-type transformer in accordance with the presen-t invention when connected for operation with respect to a square wave input derived from a 30-volt dc source.
Fi~. 5 is a schematic diagram of the primary winding for a ferro-resonant-type transformer in accordance ~:ith the presen-t invention when connec-ted Eor operation wi-th respec-t to a s~uare wave input derived from a 60-volt dc source.
Fig. 6 is a schema-tic diagram of the primary winding Eo.r a Eerro-reson~n-t---type -transformer in accordance wi-th -the present invention when connected for operation with respec-t to a square wave input derived from a 120-volt dc source.
Fig. 7 is a schematic diagram of -the secondary winding for a ferro-resonant-type transformer connected -to a capa-citor -for resonant operation near the desired frequency of operation.
Fig. 8 is an overall schematic diagram of a ferro-resonant transformer in a typical connection configura-tion.
Deseription of Preferred Embodiment Now referring to the drawings, and first to Fig. 1, 2 and 3, it is typieal that a transformer employ a stack of laminated parts. The number of laminates is not so material as the dimension of the stack-. In a 1000 VA ferro-resonant-type transformer in accordance with the present invention it has been found convenient to provicle stacks of grade Ml9 steel laminates that is 3 3/4 inches high i.n depth dimension 10 for each the eenter leg and the -two external legs.
Width 12 of the center eore leg 11 is 1 1/2 inches and width 1~ of eaeh of the external legs lS and 17 is 3/4 inehes.
~lenee, the dimension in eross-seetion of the sum of the e~ternal legs is ec~ual to that of the eenter leg.
It is typical to have the primary winding and the seeondary winding of a conventional transformer wound on bobbins made of glastic, a non-magnetie combination of fib~r~las and plastic. For conventional transformers having eenter eore laminates 1-1/~ inches wide, -the stack is nor-mally 3 inches. Therefore, two bobbins are used to make one bobbin 16~ Split 18 shows where these two bobbin parts are joined.
Turns ~0 for the primary winding are shown in Fig. 3 Wound on bobbin 16. In a similar fashion -turns are wound on a separate bobbi.ll for the secondary windi.ng. The windings are sepclrated frorn each other by an air gap. Eor tl-e trans-formel. beiny de<,cri.bed, -the air gap between the center leg ancl external le~3 is 3/4 of an inch wide, as identi,fied by nwlleral 22. A shunt 24 fills most of the air g.lp/ w;dth dimc~nsion 26 being 0.660 of an inch. The depth dimension is 3 inclles and the height is 0.98 of an inch. The shunt is also made of laminated sections, the laminations bei.ncJ shown endwise in Fig. 3 for the shunt. A simi.lar .shun-t 28 is prov.ided in the opposite air gap. Pieces of "NO~EX"* fill up the remainder of the air gaps not occupied by the shunts.
The principal flux path for the primary windi.ng is shown in Fig. l as ~p and the principal path for the flux pa-th related to the secondary winding is shown in Fig. l as 0s It should be understood that complementary paths for both windings also pass through the other external leg in acldition to the l.eg illustrated. There is some flux :for both windirlgs that travel the entire core length, and thus also pass through the other winding from -the windi'ng creatin~ the :~: lu~
The secJmc~llt:s or the windings which overall. ma!ie up thc primary windi3ly just descri~ed are shown in Fiys. 4, 5 and . In Fig. ~, wind:iTIy 30A and 30B comprise the E:irst two .layers; windincJs 32A and 32B comprise the second two layers;
windings 3~A and 34B comprise the third two laye-s, and windinc3s 36A and 36B comprise the fourth two layers. Each layer set is sel:~arated by an insulatin~ layer of "NOME.X"* and the parallel connections are made as shown. Small driver windin~s 38 and 40 share the final layer. Each of the four * trade mark 8 windings comprise 46 turns of number 14 wire. The driver windings each have 5 turns of number 16 wire.
Fig. 5 shows a configuration wherein the same four windings 30, 32, 34 and 36 are used wi-thout the ccnter tap connections emp~oyed in Fig. 4. Fig. 6 shows a conficJura-tion wherein winciings 30 and 32 are connected in series and windings 34 and 36 are connected in series and the connec-tion bekween the two series connections provides a center tap for the ent:ire primary. Again, the driver windings are the same as for the Fig. 4 and Fig. 5 structures.
The secondary winding comprises 238 turns of number 12 wires and is wouncl to provide seven layers of 34 turns per layer. Taps are provided at the 72nd, 93rd and 162nd turns to provide 120-volt, 240-volt and 277-volt taps for a 400-volt overall secondary. Capacitor ~2 across the secondary at 39 microfarads tunes the secondary to a resonant fre-quency ~us-t off 60 Hz for successful ferro-resollant opera-tlo~l.
~ typical overall schematic diagram for the ferro-resonant-type transformer just described is shown in Fig. 8.
Such a~structure provides operation of the ~)rimary winding in the ]inear ranye and the secondary winding in a satisfactory saturated mode for variatlons 85 to 100 per-cent of the voltac~e inputs shown in Figs. 4, 5 and 6.
Regula-tion can be improved with a ]arger capacitor 42, but losscs do increase. Ilowever, with the values shown, al-though greater -than with prior art ferro-resonan-t trans-formers, the losses are not great.
~ regulation ratinc3 of 2-1/2 is a cor~lon design goal ~ " ,J _ g (volts in secondary times circulating current equals 2-1/2 times the VA rating for the primary). In this case, the circulating current is a little over 6 amperes for an overall regulation rating of 2.8, which is quite goodO
The output waveform includes some high harmonic dis-tortions which can be filtered out by appropriate components (not shown), if desired. Also, the output waveform can be further shaped to be more sinusoidal, if desired.
While a particular embodiment of the invention has been shown and described, i-t will be understood that the inven--tion is not limited thereto, since many modifications may be made and will become apparent to those skilled in the art.
Claims (3)
1. A ferro-resonant-type transformer, comprising a laminated center leg made of conventional transformer steel, a pair of laminated external legs made of conventional transformer steel, the cross-sectional dimension of the center leg equalling the sum of the cross-sectioal dimensions of said external legs, a primary winding wound about said center leg having sufficient turns and resistance so as to operate within the linear range with respect to applied rated square wave voltage, a secondary winding wound about said center leg and spaced apart from said primary winding, and a magnetic shunt between said primary winding and said secondary winding, said secondary winding having sufficient turns and resistance so that the steel in the center leg underneath said secondary winding and the return flux path through said external legs and said shunt, flux saturates for rated volt amperes, therefore resulting in a non-square wavc output with good regulation and without excessive losses in ferro-resonant-type transformer action.
2. A ferro-resonant-type transformer in accordance with claim 1, wherein said primary winding is wound in insulated layers readily tapped for connection to multiple applied voltage connections to obtain rated volt ampere performance.
3. A ferro-resonant-type transformer in accordance with claim 1, wherein each of said primary winding and said secondary winding are wound on non-magnetic bobbins.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US22380081A | 1981-01-09 | 1981-01-09 | |
| US223,800 | 1981-01-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1181495A true CA1181495A (en) | 1985-01-22 |
Family
ID=22838021
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000387580A Expired CA1181495A (en) | 1981-01-09 | 1981-10-08 | Ferro-resonant-type transformer |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0056133A3 (en) |
| AU (1) | AU7613581A (en) |
| CA (1) | CA1181495A (en) |
| ES (1) | ES507330A0 (en) |
| GB (1) | GB2091045A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU587774B3 (en) * | 1989-04-28 | 1989-08-01 | Trestoto Pty Limited | A magnetic circuit arrangment |
| CN108335885B (en) * | 2018-04-25 | 2024-03-01 | 上海良治电器技术有限公司 | Waveform compensated ferromagnetic resonance voltage stabilizing transformer |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3129383A (en) * | 1959-11-14 | 1964-04-14 | Karo David | Voltage stabilizing electrical transformers |
| US3456223A (en) * | 1967-09-15 | 1969-07-15 | Gen Electric | Voltage stabilizing transformer with variable air gap characteristics |
| US4080725A (en) * | 1974-06-26 | 1978-03-28 | Thomas & Skinner, Inc. | Ferromagnetic core with variable shunt air gap and method of making it |
-
1981
- 1981-10-08 AU AU76135/81A patent/AU7613581A/en not_active Abandoned
- 1981-10-08 CA CA000387580A patent/CA1181495A/en not_active Expired
- 1981-11-20 ES ES507330A patent/ES507330A0/en active Granted
- 1981-12-17 EP EP81110548A patent/EP0056133A3/en not_active Withdrawn
- 1981-12-30 GB GB8139096A patent/GB2091045A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0056133A3 (en) | 1982-09-22 |
| GB2091045A (en) | 1982-07-21 |
| AU7613581A (en) | 1982-07-15 |
| ES8302354A1 (en) | 1983-01-01 |
| ES507330A0 (en) | 1983-01-01 |
| EP0056133A2 (en) | 1982-07-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |