US2017273A - Electrical system and apparatus - Google Patents

Description

Oct. 15, 1935. C. P, BOUCHER 2,017,273

ELECTRICAL SYSTEM AND APPARATUS Inc/ew?! C'kaa-Zelowcker Oct. 15, 1935. Q p. BOUCHER y 2,017,273

ELECTRICAL SYSTEM AND APPARATUS Filed March l2, 1934 2 Sheets-Sheet 2 71 'UWM Invenlfor: CkarkJPBoucer,

3y" MM/QW Patented Oct. l 5, 1935 STATES ELECTRICAL SYSTEM AND APPARATUS Charles P. Boucher, Montreal, Quebec, Canada Application March l2, 1931i, Serial No. H5325 Bitti@ 11 Claims. (Cl. liti-B119) This application is a continuation in part of my Patent No. 1,950,395 granted March 13, 193e and entitled Means for operating gas filled luminescent tubes, which in turn is a continuation in part of my Patent No. 1,950,394 granted March 13, 1934 and entitled Electric operating device for neon and like signs.

' This invention relates to electrical systems and apparatus and more particularly to electrical sys- .0 tems including loads having negative electrical resistance characteristics, especially luminescent tube systems and apparatus for operating the same.

One of the objects of my invention is the pro- 15 vision or a simple, economical and thoroughly reliable system and apparatus for the inexpensive and highly efiicient operation of a plurality of loads having negative electrical resistance characteristics, such as for example, luminescent tubes zo or gaseous conduction devices of various shapes and sizes comprising for example, a luminous display.

Another object is the achievement of clear and brilliant operation of luminescent tubes or gaseous conduction devices of the character indicated. with a minimum of expensive and/ or cumbersome equipment, all at a desired high power factor and good operating eiiciency.

Another object is the provision of inexpensive and compact electrical apparatus for uniformly operating, from a readily available source of a1- iernating current electrical energy, a plurality of individual loads having negative electrical resistance characteristics, such as luminescent tubes wherein the several loads continuously vary in character because of various individual differences between the loads resulting, for luminescent tubes, from differences in the lengths of the tubes, differences in the sectional areas of the tubes, diierences in the nature and pressures of the gases lling the tubes and other physical diferences which affect the electrical characteristics, such as the striking potential, the cut-ofi potential and the current carrying capacity of the tubes employed.

Other objects in part will be obvious and in part pointed out hereinafter.

The invention accordingly consists in the va'- rious combinations of elements, features of construction and arrangements of parts, as described herein and the scope of the application of which is indicated in the following claims.

In the accompanying drawings Figure 1 is a diagrammatic representation of my system and 5 apparatus for operating a number of luminesthe tube may be maintained no longer.

cent tubes comprising a single luminous display,

Figures 2, 3 and e are diagrammatic representations of modified systems and apparatus ior operating a number of luminescent tubes comprising a single luminous display unit, d

Figure 5 is a diagrammatic representation of my transformer apparatus as employed in the system indicated in Figure 3, and

Figure 6 is a detached diagrammatic sectional view on an enlarged scale of a part oi my transil@ former apparatus shown in Figure 5.

As conducive to a clearer understanding of certain features of my invention, it may be noted at this point that in the operation of a number of devices having negative electrical resistance lid characteristics, such as a number of luminescentgas iilled tubes comprising a single luminous sign or display, certain practical dimculties in operation are encountered, because of the inherent unstable operating characteristics of the individ- 9@ ual tubes or devices. 1

in operating such devices from a source of alternating current electrical energy, the instantaneous resistance of any one tube or device varies greatly from the time when the instan- 25 taneous value of the applied potential is insuilcient to cause an ionized condition of the con.- tained gas (during which the tube is of high electrical resistance, is non-conductive and is nonluminous) and when the applied potential in s@ either or" the alternatively positive or negative portion has risen to such a value as to ionize 'the contained gas and to cause the tube to become a conductor of very low resistance and luminescent. Where the ionized, and hence conductive, cong5 dition of any one tube is established a substantial current flows through the tube until the continuously changing applied potential has fallen to such a low value that the ionized condition of At this t@ time the tube again becomes non-conductive and non-luminous and remains so until the instantaneous value of the applied potentia'i again rises, in following through the cycle oi alternations, to a point suihciently high to again cause the gas to become ionized, conductive andlrminous.

The amount of light energy produced perunit time by any one luminescent tube of the character indicated, depends, first, upon the proportionate length of time that the tube is rendered conductive' (the proportionate period between the time when the instantaneous applied ypotential becomes suflicient to ionize the gas contained in the tube and the time when this potential falls 59 to such a low value that the ionized condition may be no longer maintained) and, second, upon the average brilliancy of operation of the tube throughout this conductive period, which is dependent upon the average current density within the tube, a factor which is directly influenced by the impedance of the circuit supplying the tube with electrical energy.

Likewise, it may be noted that in the operation of a number of devices or ltubes of the character indicated, a number of practical difficulties are encountered because oi unavoidable differences in the electrical characteristics of the several tubes or devices. Because of certain necessary differences in the physical characteristics of the tubes, such as differences in the lengths of the tubes, the tube diameters, the nature oi' the contained gases employed and the pressures of these gases, the electrical characteristics of several tubes are of necessity considerably different. Thus, because of these physical diiferences these several tubes have different striking or ionizing potentials, different potentials at which the ionization may be no longer maintained, different electrical conductance (or resistance) during the ionized conductive period and the like.

Since, as more particularly indicated above, the resistance of am7 one of the devices or gas-filled tubes of a single luminous display varies greatly from the unionized, non-conductive condition of the gas (where the electrical resistance is very high) to the ionized, conductive condition (where the resistance is very low), a characteristic which renders the tube inherently unstable, it is particularly difficult to operate more than one of these tubes or devices in a reliable manner.

In heretofore known and/or used systems and apparatus for operating a plurality of devices having negative resistance characteristics, such as a plurality of gas-filled luminescent tubes comprising a single luminous display, great diillculty is experienced in achieving uniform, stable operation of the tubes or devices. Likewise, considerable diiculty in the operation of such systems is experienced because of the exceedingly high operating potentials required to strike or effect an ionized condition of the tubes rendering a'series operation of the tubes or devices impracticable commercially because of the objectionably high potentials thus necessarily encountered.

In heretofore known systems of the character indicated the several devices or tubes employed, because of the inherent instability, the. high striking potentials and varied individual electrical characteristics of these tubes or'devices, as more particularly indicated above, are either energized from individual sources of high potential alternating current electrical energy or supplied with energy fromthe various phases of a polyphase electrical system, or excited from separate high potential electrical transformer apparatus connected with a single source of electrical energy. All of these systems and apparatus are ineicient, expensive and cumbersome and costly to maintain and operate.

Y', Accordingly, one of the outstanding objects of my invention is to provide a. system and apparatus of a simple, compact and inexpensive con struction foroperating a number of high potential tubes or devices of the character described above, in an efficient, economical and thoroughly reliable manner, encountering electrical potentials within a prescribed maximum limit, from a readily yavailable source of alternating current electrical energy to achieve a uniform brilliant display (for al plurality of luminescent tubes) of a desired character.

Referring now more particularly to the practice of my invention, attention is directed to Figure 1 of the drawings, wherein a plurality of devices having negative electrical resistance characteristics, illustratively a plurality of luminescent gas-filled tubes I0, II, I2 and I3, are suitably mounted in a desired arrangement comprising a luminous display or sign I0-II--I2-I3. The devices or tubes I0, II, I2 and I3 have approximately the same current ratings but have slightly different ratings in starting potentials. Thus, for example, the striking potentials of the several luminescent tubes are approximately proportional to the relative lengths of the tubes, and as indicated in Figure 1, the shorter tube I2 is of the lowest striking potential and the striking potentials of the remaining tubes are in the order I0, II and I3.

2 The several luminescent tubes, as more fully described in my Patent No. 1,950,394 referred to above, preferably comprise elongated clear glass envelopes having sealed-in electrodes at opposite ends. These envelopes are filled with one or more gases at low pressures, neon for example, having the property of becoming luminescent upon being electrically excited. For each luminescent gasfllled tube, as the column of'gas contained within the glass envelope is subjected to successive high values of electrical potentials applied across the tube electrodes in a manner more particularly described hereinafter, the column of gas becomes ionized and the tube, formerly non-conductive, is rendered conductive permitting the flow of an electrical current through the ionized gas and the emission of a luminous glow, which for neon is red orange in color. The brilliancy or intensity of this color, as more particularly indicated above, is dependent largely upon the current density within the column of ionized gas. For low current densities (where the flow of current is greatly limited by the impedance of the electrical circuit supplying a luminescent tube, for example) the blow is weak and poorly distributed along the length of the tube; for reasonably high current densities, however, the tube gives forth a luminescent, brilliant glow which is Well distributed along the entire length of the tube. For maximum emcient luminescence sustained high current densi- A ties are desired for a maximum proportion of the successive periods (corresponding to the alternations of the source of electrical supply energy) during which the tubes are rendered conductive, all as more particularly indicated above. Due, however, to the inherently unstable characteristics of the devices or tubes of the character indicated, special precautions are taken to assure a substantially even, sustained flow of current which is sufcient to give a desired uniformly high current density in the several luminescent tubes comprising the luminous display and yet which is insufficient to burn out or otherwise damage the various tubes and the associated supply system and apparatus, all as more particularly described hereinafter.

Referring now back to Figure l, the several luminescent tubes I 0, II, I2 and I3 are preferably supplied with alternating current electrical energy from a readily available single phase source I I, illustratively 220 volts at 60 cycles per second, which is connected to the luminescent tubes by way of electrical apparatus, generally indicated at I5 and more fully described below.

In accordance with the provisions of my invenaon/,avav

tion -electrical lapparatus Il includes a primary transformer winding I8 and secondary windings, illustratively five, I1, I9, I9, 20 and 2| mounted upon acommon core 22; the total number of secondary winding coil sections being greater by one than the total number of the devices of negative electrical resistance characteristics, illustratively four, supplied with electrical energy. In order that luminescent tubesl III, II,' I2 and I3 'of maximum lengths and maximum potential ratings may be employed with an electrical transformer apparatus of a specified maximum permissible potential to ground, each luminescent tube is supplied with the high potential electrical energy of two of the transformer secondary winding coil sections connected in series. Each of these coil sections, then, is rated at about onehalf the maximum potential required to operate the tube, illustratively i3, of maximum potential.`

rating. For reasons of simplicity and economy in construction, the several coil sections i1, i8, it, 2e and 2i are preferably oi like size and voltage ratings, although as will appear more fully hereinafter, the coil section il maybe oi a current carrying capacity of about pur times that of coii sections i8, it, it and it; the current carrying capacities of coil sections it, iii, 20 and 2i being v reduced to effect a saving in copper where desired.

One end of each of the transformer secondary winding coil sections I1, I8, I9, 2|) and 2| is lconnected to a conductor 23 thereby establishing a point of common potential. For example, as seen in Figurel, the left ends Isa, I9a,`20a and 2Ia of the respective coil sections Ill",v I9, 20 and 2| and the right end |1b of coil section I1 are all con- .nected to the common conductor 23, thus establishing a point of common potential and placing coil section I1 in opposed phase sequence to the coil sections I9, I9, 20 and 2| of like phase sequence, as `diagrammatically indicated by the arrows placed immediately above the coil sections.

In order that full electrical potential may be applied vacross the terminals of the several devices of negative electrical resistance characteristics, the free end of the coil section I1 of opposed phase sequence, illustratively the left coil end IIa, asseen in'Figure 1, is connected to an output terminal conductor 24, connected by way of conductors 25, 26, 21 and 29 to the respective devices I0, II, I2 and I3, and the free ends of coil sectionsI I9, I9, 20 and 2l, illustratively the right coil ends Ib, I9b, 20h and 2Ib. respectively are connected to the respective output terminal conductors 29, 30, 3| and 32 connected to the respective devices III, II, I2 and I3.

The several devices or tubes I0, II, I2 and I3 are supplied with electrical energy by secondary winding coll section I1 in combination `with coil sections I9, I9, 20 and 2 I respectively; the potential of the electrical energy supplied these several devices being equal to the s'um of the potential of coil section I1 and the respective potentials of coil sections I9, I9, 2II 'and 2|.

In the operation of my electrical system and apparatus alternating current electrical energy from source I4 is'supplied the primary-winding Il-of my transformer apparatus by way of conductors 33 and hlftherebyv establishing an alter- `nating magnetic flux in'transiormer core 22. The alternating magnetic flux interlinks transformer secondary winding coil sections I1, I9, I9,

2l and 2| with primary winding I6; the alternations of Ithis flux' establishinga high'value of output v.potentials across the coil ends of the several secondary winding coil sections.

the instantaneous values of the various applied 5 potentials become sufficient to establish an ionized condition within the respective tubes. Because of the lower striking potential of one of the tubes, Illustratively tube I2, as indicated above, the gas of this tube becomes ionized, the tube is rendered 1 conductive and a current begins to flow starting, for example from coil section I1 by way of coil end Ila, conductors 24 and 21 through tube I2 and by way of conductor 3|, coil end 20h, coil 29, coil end 20a, conductorl 23 and coil end ilb back l5 to coil il. This current renders the tube luminescent.

In ordert'o prevent the current flowing in this tube from rising to anobjectionably high value when the resistance of the tube (sufficiently high ai) so that under substantially no `load conditions (conditions existing for the initial portion ofy each half cycle of the valternating current electrical energy, and thus for the magnetic flux interlink- 35 ing the transformer primary Winding and the se'condary winding coil sections) substantially all of the magnetic llux linking primary winding I6 also links coil sections I1 and 20 to give maximum output potential across the respective terminal 40 conductors 24 and 3| anid thus impress a full value A of the instantaneous potential across the trminals of tube I2.

As the current flowing in the circuit including vtube I2 tends to increase and reach an objection-- 45 ably high value, a Amagneto-motive force is produced by this current which tends to increase and oppose the course of the magnetic flux (caused by the primary magneto-motive force resulting from the flow of current through the 50 transformer primary winding I6) through that section of the magnetic core 22 linking the transformer secondary winding coil section 20. Due to this opposing force the magnetic flux tends to course through the auxiliary core section 35 and 55 the included air gap, directly detracting from the magnetic flux coursing through coil section 20 and interlinking the primary winding I6 with the secondary winding coil section 2II. As a reslt, the potential induced in coil section 29 is 60 greatly decreased, thus decreasing the sum of the potentials induced in coil sections I 1 and 20 which is impressed across thetterminals ofthe luminescent tube I2.

The/change in the course of the magnetic flux 65 around transf rmer`secondary Winding coil sec- A (tion 20 has but relatively little effect upon the magnetic flux linking primary coil winding I6 and secondary winding coil sections I1, I8, I9, 20 and 2|. Under the action of the continuously 70 increasing magnetic flux (the magnetic flux increases with the primary magneto-motive'force f as the alternating current electrical energy supplied primary winding I6 continues in' its rising cycle) coursing through core 22 and interlink- 75 24-32 quickly reach the striking potentials of the remaining devices or tubes I0, II and I3 ref` spectively connected to these conductors. The luminescent tube I0, having a striking or ionizing potential immediately above that of tube I2 of lowest value, as indicated above, is the second one to become ionized. Upon ionization oi!y the gas column of tube I0 this tube becomes a relatively good conductor of electricity and a current immediately tends to flow in the electrical circuit including tube I0 and secondary winding coil sections I1 and I8 which may be traced for example, from coil I1, coil. end I'Ia and conductors 24'and 25 to the luminescent tube II)V and from this tube by way of conductor 29, coil end I8b, coil I8, coil end I8a, conductor 23 and coil end IIb back to coil II. As more particularly described above in connection with the description of `electrical circuit conditions attendant the ionization of tube I2, a magneto-motive force opposing the coursing of the main magnetic ux interlinking primary winding I6 and secondary winding coilsection I8 is established, This causes a heavy magnetic flux to course through the auxiliary core section 88 mounted on core 22 embracing coil section I8 (and the included air gap between core 22 and one end 38a of this auxiliary core or shunt section) and that portion of the core 22 linking coil I8, forming a complete closed auxiliary magnetic circuit. With the establishment of the auxiliary magnetic circuit a very high back electro-motive force is induced in coil section I8 which directly opposes the electromotive forces induced in coil sections I1 and I8 resulting from the changing magnetic flux inter- `linking secondary coil sectionsI'I and I8 with primary winding I6. 'I'his back E. M. F. is sufllcient to limit the rise of current in tube I0 to desired values; a further limitation of current being achieved, to a minor extent. by the back E. M. F. induced in coil section I1, as more particularly described above.

The opposing action of the magneto-motive force produced by the rising current in coil section I8 furthermore causes the major portion of the main magnetic flux coursing through core 22 to pass along the auxiliary magnetic circuit afforded by auxiliary core section 86 and the included air gap, thus directly detracting from the total magnetic flux interlinking primary winding I8 and'secondary winding coil section I8, and accordingly reducing the direct electro-motive force induced in coil I8 and decreasing the sum of the direct induced potentials of coils Il and I8 applied across the terminals of tube I0. This further decreased instantaneous value of the applied potential is further eilective in preventing the current flowing in the circuit including tube I0 from rising to excessively high values. 'Ihe resultant applied potential, however, is suilicient to maintain the tube in an ionized condition.

Upon further increase in the main magnetic flux interlinking primary winding I 8 and secondary winding coil sections I'I, I8, I9, 28 and 2I incident to the increased primary magneto-motive force as the applied alternating current electrical energy continues to increase in its rising cycle, the potentials induced in secondarywinding coil sections I'I--IS and I12I continue to increase. The values of the striking potentials 'of devices or tubes II and I8 are;successively l reached in a manner more particularly described above, causing an ionized and conductive condition of the tubes tobe successively established permitting the iiow of electrical current in the circuits including these tubes; the ilow of current .being limited by the high back. E. M. F. induced in the respective coil sections I8 and 2| embraced by respective auxiliary core sections 31 and I8 mounted on the main core 22, as well vas to a minor extent by the self-induced back E. M. 1". in the common coil section I'I and the reduction in the direct E. M. F. induced in the respective coil sections I8 and f2I resulting from the decrease in magnetic ilux interlinking coil sections I9 and 2I with primary winding IB incident tothe coursing of the main magnetic flux through the auxiliary core sections 31 and 38 in a manner ,more particularly described in connection with the successive starting of luminescent tubes I2 and I0.

A further limitation upon the instantaneous value of the potential directly induced in coil sections I1--I8, I1I8, I120 and I'l-2l and applied across the terminals of the respective luminescent tubes I8, Il, I2 and I3, is achieved 4Where desired by including an auxiliary core shunt posing the increase of the magnetic flux interlinking primary winding I6 and the various secondary winding coil sections tend 4to rapidly increase to high values which tend to occasion a high instantaneous value of current supplied primarywinding I6 by source I4 and a greatly increased magneto-motive force in transformer primary winding I6.

'l'he tendency for a current of high instantaneous value to flow in primary winding lII and def velop a correspondingly high magneto-motive force under the action of the applied potential increasing in its cycle of operation, is oil'set by the back E. M. F. induced in this Winding (resulting from the initial increases in current) opposing the applied E. M. F. Because of the auxiliary magnetic path interlinking primary winding IB (this magnetic. path 4including auxiliary core section 38, air gap,38af-22 and the portion voi core section 22 immediately linking winding IB) an auxiliary magnetic flux of considerable proportions is` established upon an initial flow of current in winding I6 causing the production of an induced back E. M. E. of relatively great mag.- nitude opposing the applied E. .thereby limiting the flow of current inthe primary winding, the magnetic flux interlinking primary and secondary windings, the potentials induced in the secondary windings, and the secondary output current, as more fully indicated above.

The extent of the influence of these various factors limiting'and controlling the flow of current in the various luminescent tubes or devices having negative resistance characteristics, as discycle supply of alternating cunentelectrical encussed above, is so proportioned as to give uniform and brilliant operation of the tubes, as by properly proportioning the relative sectional areas of main core '22 and auxiliary cores I5, 35, 31 and 38, as well as by employing core sections oi such sectional areas to obtain desired magnetic flux densities and by employing desired lengths of air gaps serially included with these auxiliary cores. Ordinarily these adjustmentsv are arrived at empirically.

' When all oi the tubes are in the ionized conductive condition giving forth a brilliant, luminous glow of a conguration conforming to the arrangement of tubes'comprising the sign or display Ill-I-I2-l3, this luminescent condition persists throughout the further progress of the applied alternating current electrical energy in its assumed half cycle of operation. The tubes remain conductive and luminous until the instantaneous value of the 'secondary outputl luminescent tubes Il, l and lzlbecome successively unionized, non-conductive and non-lumif nous..

As the applied alternating current electrical energy continues' through its cycle of alternations, a potential of sufcient value is soon applied across the 'terminals of luminescent tube I2 to ionize the gas column of this tube and rendery it conductive and luminous, thus repeating the operating condition described above. As the cycle progresses tubes I0, Il and I3 are successively rendered conductive and luminous. Further progress of the cycle of operatiorrre'nders all tubes unionized and non-luminous.

'Ihe several luminescent tubes are rendered luminous and non-luminous once for each half cycle of the alternations of the alternating current electrical energy source of supply- For a 60 ergy the tubes are thus rendered alternatively conductive and non-conductive, and consequently luminous and non-luminous 120 times a second.I

Dueto persistence ot vision the tubes appear to glow continuously.` f l Because of .the manner in which luminescent tubes of the character lindicated or like devices of negative electrical resistance characteristics become conductive and non-conductive almost instantaneously, a transient wave oi potential and currentis set un on the various conductors conn necting the several tubes to the high. potentiai transformer apparatus. The provision of auxiln tary magnetic core sections embracing the sev= eral individual transformer secondary winding coil sections oi tne transformer apparatus lends emu coil section such relatively high values of` conductance under load as to materially increase the tree periods of these transient manifestations and to eiiectively damp them to minimize varia tions in current densities and hence variations in luminescence in the several individual tubes and also minimize disturbing electro-magnetic radio tions ci a radio frequency range.

Where there is considerable difference between the physical dimensions of the several wir nascent tubes employed, as for example where the lengths of the various tubes diner `consider-- ably, the relative duration of the luminous-periods of ,the several tubes (in general the tube first rendered luminous is last rendered non-luminous, and the tube last rendered luminous is the tube ilrst rendered non-luminous, permitting a double divergence in the luminescent periods of any two tubes) may diier so widely where transformer apparatus including secondary winding coil sections of the same size and voltage ratings are employed as to give an unbalanced luminous appearance, the several individual secondary winding coil sections connected to each oi the lumines-y cent tubes may be proportioned in voltage rating so that the coil section of highest voltage rating is connected to the tube of tential and the remaining tubes correspondingly connected to coil sections of proportionately def creased voltage ratings. With the -several individuallsecondary winding coil sections proportionately rated to correspond to the striking po` tentials of the several luminescent tubes, all of the tubes Vwill be rendered ionized, conductive and luminous atsubstantially the same instant and subsequently rendered unionized, non-conductlve and non-luminous. at a subsequent instant giving a luminous period for all tubes of about the same duration.

Where a number of luminescent tubes of con-f siderably diierent current ratings v(tubes containing different/gases at dlierent pressures or tubes of different diameters) are employed comprising a single luminous'fdisplamt is desirable highest striking poto supply certain of the tubes with agi-eater cu'rrent vthan the otherts'inorder to preserve a substantial Auniform current density', and hence -a substantially. uniformluminescence in theseveral tubes employed. Thus, referring to FigureA 2 `a plurality of tubes 40, 4l, 42 and43 of substantially like striking potentialf'and r uired sustaining potential characteristics but i.' different current carrying capacities, comprising a single display 40-4I-42-43 are-respectively connectedh by Way of conductors 44,' 4,5, 46 and 41. to one end of each of transformer secondary winding coil sections 48, 49, 50 and-5I mounted o a. common core 52. Tubes 40, 4|, 42 and 43" are likewise connected by the respective conductors 53, 54, 55 and, 56 and the common conductor 5l to one end of a common transformer secondary -windixig coil section 58, the other end of which is connected to a conductor 59 connecting the free ends of coil sections 48', 49, 50 and 5i withthc free end of coil section 5t, establishing 'a point of common potential and placing coil sections 48, 49, 50 and 56 in'like phase sequence and coil section 58 in opposite phase sequence, all as more particularly described above in connection with lthe system and apparatus shown in Figure l.

Transformer core 52 is energized by transt@ former primary winding mounted on core t?, anrlsupplied with alternating current eiectricsl energy from a sirmle phase source oi supply Si connected to Winding il@ by way ci conductors G2 and GS.

in the operation oiT the system shown in Figure it, the current permitted to flow in each of the transformer secondary output circuits including the several iescent tubes is limited in c ne more particularly described alcove, i@

by auxiliary magnetic circuits linking the individual transformer secondary winding Ycoil secn tions., 'The magnetic paths for the auxiliary magnetic circuits linking the individual coil sec tions are provided by the respective auxiliary mitted to flow in the tubes of maximum current carrying capacities, illustratively luminescent f tubes 4| and 43 of increased tube diameters, full potential is desirably induced in transformer secondary winding coil section 08 `which is common to all tubes. To achieve the full current limit-v 10 ing inductance effect of the transformer primary winding on the current flowing in the several luminescent tubes after the conductive/cond'if tions of these tubes have been established, and to furthermore realize a reductionv in the magnetic l5 iiux interlinking the transformer primary windlng and the transformer winding individual coil sections, an auxiliary shunt magnetic circuit ris provided around the transformer primary winding by way of an auxiliary core section 80, suit ably mounted on core 52. In order that full potential may be induced in the common secondary coil section 80, as indicated above auxiliary core section 80 is positioned to embrace both primary winding 80 and secondary winding coil 20 section i0. Maximum magnetic linkage between' primary winding 60 and secondary winding coil section 50, and thus a maximum induced potential in coill section 50, is assured in a simple, eilicient and reliable manner.

Improved operational conditions of nur system and apparatus, especially inthe matter of power factor (a feature of considerable commercial im portance) is achieved by omitting the auxiliary core section s embracing transformer primary -winding` of .my-apparatus and substantially divorcingv auxiliary core sectlims individual to the'transformer secondary winding coil sections 'connected to` individual luminescent tubes, from y transformer core interlinking the priao J- mary. Winding with the several transformer secomini-y winding coil sections in order to substan- V tially reduce the'tendency toward the production of connicting magnetic neldswithin the main transformer 'core and the consequent electrical "eddy currents resulting in objectionable core heating 'and'high core losses.

Thus,referringtoligure3 ofthedrawings, a transformer .primary winding 10 supplied with alternating current electrical energy from an -available source 1I and connected thereto by way ofconductors 12and10,ismounted onamagnetic core 14/in any suitable manner. Trans-v former winding coil sections `1l, 18, 11. 10 and 'I9 are likewise mounted on core 14, One end of 56--each of thesecondary winding coil sections 1s connected to a common conductor 00 establishing a point of lcommon potential therefor and f connecting one of the coil sections 15 in phase opposition to the remaining coil sections 18, 11, 00 10 and 1.0. Conductor 00 is conveniently grounded as at 0I giving a symmetrical or balanced electrical system and establishing a maximum potential to ground for the system equal ,6 yto the potential induced in the secondary winding coil section of maximum voltage rating.

A number of luminescent gas-nlled tubes 02, 03, 04 and 08 are respectively connected by way of conductors 00, 01, 00 and 00 to a common con- .ductor 00, connected to the free end of trans former secondary winding coil section 10 of opposed phase sequence. These'several gas-filled tubes are also connected by way of conductors v Il, 02, 0I and 04 to the free ends-of the respec- 1I-tive individual transformer secondary winding coil sections 18, 11, 18 and T9 of like phase se quence.

In the operation of this modification of my system and apparatus, the instantaneous current supplied luminescent tubes 82, 83, 84 and 05 when these tubes are rendered conductive, as more particularly described above in connection with the operation of the system shown in Figure l A of the drawings. is greatly limited by the inductive reactance of the coil sections, included in the circuits of these tubes. This limiting inductive effect is greatly increased because of the indivldual magnetic circuits interlnking the several transformer secondary winding coil sections. Y

Individual auxiliary core shunt sections 90, 98, 91 and 98 forming complete magnetic circuits respectively interlinking individual coil sections 18, 11, 18 and"19, are mounted on the main core 14 in any sul-table manner to provide a small air gap between the auxiliary core sections and the 20 main transformer core and electrically insulate the several auxiliary coresections therefrom. Conveniently, auxiliary core sections 95, 98. l1 and 98 are spaced and electrically insulated from core 14 by the respective strips of electrical insu- 25 lation 99, |00, IOI and I02` interposed between the several auxiliary core sections and the main core.

As the current tends to rise in the several individual transformer secondary winding coil 00` sections 18, 11, 18 and 19, as the respective luminescent tubes 82, 83, 04 and 85 connected to these coil sections are rendered conductive, a high back E. M. F. is induced opposing the direct .induced ELM. F. The flow of current in the individual tubes is thus individually controlled: and limited lto a desired value. The relative sectional areas and permeabilities of the auxiliary core sections and main core, as well as the air gaps between the two, largely determine the con- 40'- trolling and limiting effect upon the current. X 'Ihe use of completely closed auxiliary coredsections interlinking individual transformer second' ary winding coil sections furthermore improves the operating powerfactor and eiliciency of the 45 system and apparatus and in addition further' decreases the percentage variation in the transient current and potential incident to the sudden rendering of the tubes alternately conductive and nonconductive, as more particularly 50 described above, thus maintaining m'ore uniform 'brilliant illumination of the luminescent tubes and a reduction in the electromagnetic energy radiated from the system as well. Where desired the current supplied lumines- 55 cent tubes 02, 83, 04 and 85 (see Figure 4) may be uniformly controlled and limited by an auxiliary magnetic circuit |03, interlinking the transformer secondary winding coil section 1l in addition Ato the individual controlling and limiting 00- effects of individual auxiliary core sections 08, 98, 91 and 90 of respective individual coil sections 18, 11, 18 and 19. 'I'he auxiliary core section |08 is mounted on the main transformer core 14 in any suitable manner with a strip of electrical 05I insulation |04, interposed between the main core and the auxiliary core. With this construction the auxiliary core sections 95, 96, 91 and 90 indi-4 vidually interlinking the respective coil sections 18, 11, 10 and 19 may be of a reduced sectional-70" area as compared with like auxiliary core sec-- tions described above in connection with Figure 3 of the drawings. The relative sectional areas and permeabilities of these auxiliary core sections and-the main transformer core are such,

aormvs however, as to permit an efficient individual control of current supplied luminescent tubes 82, til, @il and 85 in order that all of the tubes may be properly operated in spite of slight variations in the striking potentials of the several tubes. Such a construction permits certain economies in manufacture, operation and maintenance.

A convenient form of construction of my transformer apparatus is indicated in Figure 5, wherein the primary coil section .10 is mounted on one leg 14a of a closed magnetic core 14. Conveniently, the one secondary winding coil section of opposed phase sequence 15 is mounted on an opposite core leg 14h. Individual transformer secondary winding coil sections 16, and 11 are conveniently mounted on core leg 14e while individual core sections 18 and 19 are symmetrically positioned on the opposite core leg 14d.

Auxiliary core sections 95 and 96 respectively -linking individual coil sections 16 and 11 (see also Figure 6) are rigidly mounted on core leg 14e in any suitable manner. Spacing between auxiliary core sections 95-96 and core leg 14o is achieved by way of a flat strip of electrical insulating material .9S-|00, such as press board. Similarly, auxiliary core sections 91 and 98 respectively interlinking coil sections 18 and 19 are mounted on core leg 14d with a strip of electrical insulating material IBI-|02 intervening.

Terminal connections from the primary winding are brought out from ccil 1D as 10a and 10b. Terminal connections for the several secondary winding coil sections 15, 1B, 11, 18 and 19 are respectively brought out as at 15b, 16a, 11a, 18a

-and 19a, while the coil ends 15a, 16h, 11b, 18h

and 19D are conveniently brought out and grounded to core 14 -to establish a point of common potential and place coil section 15 in phase opposition to the remaining coil sections, as more fully described above.

This construction provides a simple, compact and inexpensive transformer apparatus for operating a number of luminescent tubes or other devices having negative electrical resistance characteristics in a highly eflicient and thoroughly reliable manner. The transformer apparatus furthermore lends itself to an ease of handling in packing and shipping and a sureness and simplicity in installation permitting many practical savings and economies.

While in the above illustrative embodiments of my invention, systems and apparatus for the operation of four luminescent tubes are illustratively described, it will be understood that any number of individual luminescent tubes may be individually operated and controlled from a single source of alternating current electrical energy, by employing transformer apparatus having individual secondary winding coil sections one more in number than the luminescent tubes to be energized.

Thus it will be seen that there has been provided in this invention a system and apparatus in which the various objects hereinberore set forth, together with many thoroughly practical advantages are successfully achieved.

As many possible embodiments may be made of my invention and as many changes may be made in the embodiments hereinbefore set forth, it will be understood that all matter described herein or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

I claim:

1. In single phase electrical systems of the character described, in combination, a source of single phase alternating current electrical energy, a single phase electrical transformer having a primary winding and a secondary winding comprising a plurality of coil sections mounted on a common interlinking core, means connecting said transformer primary winding to said source, conductor means interconnecting said transformer secondary winding coil sections placing one of said coil sections in phase opposition to the remaining coil sections, a plurality of devices having negative electrical resistance characteristics corresponding in number to said transformer secondary Winding coil sections of like phase sequence, conductor means connecting said transformer secondary winding coil sections of opposing phase sequence to said devices, conductor means respectively connecting said transformer secondary winding coil sections of like phase sequence to said corresponding devices, and means operatively associated with said transformer core for diverting a portion of the magnetic flux interlinking said transformer primary and secondary Winding coil sections in accordance with variations in the electrical characteristics of each of said devices.

2. In single phase electrical systems of the character described, in combination, a source of single phase alternating current electrical energy, a single phase electrical transformer having a primary Winding and a secondary winding comprising a plurality of individual coil sections mounted on a common interlinking core, means connecting said transformer primary Winding to said source, conductor means interconnecting said transformer secondary winding coil sections placing one of said coil sections in phase opposition to the remaining coil sections, a plurality of devices having negative electrical resistance characteristics corresponding in number to said transformer secondary winding coil sections of like phase sequence, conductor means connecting said transformer secondary winding coil sections of opposing phase sequence to said devices, conductor means respectively connecting said transformer secondary winding coil sections of like phase sequence to said corresponding devices, and a plurality of individual core means respectively interlinking said individual transformer secondary winding coil sections for increasing the inductive reactance of said coil sections, thereby controllingthe ilow of transformer secondary currents to said corresponding devices in accordance with alterations in the electrical characteristics of each of said devices.

3.' In single phase electrical systems of the character described, in combination, a source of single phase alternating current electrical energy, a single phase electrical transformer' having a primary winding and a secondary winding comprising a plurality of coil sections mounted on a common interlinking core, means connecting said transformer primary Winding to said source, conductor means interconnecting said transformer secondary Winding coil sections placing one of said coil sections in phase opposition to another of said coil sections, a device having negative electrical resistance characteristics, conductor means connecting one of said transformer secondary winding coil sections to one end of said device, conductor means connecting another of said transformer secondary winding coil sections to the opposite end of said device, and core means interlinking one of said transformer secondary winding coil sections for increasing the inductive reactance of said coil section and thereby controlling the iiow of transformer secondary current to said device in accordance with variations in the electrical characteristics of the device.

4. In electrical transformer apparatus of the class described, in combination, a transformer core, a primary winding linking said core, a secondary winding having a multiplicity of coil sections linking said core common to said primary winding, conductor means interconnecting one end of each of saidV secondary winding coil sections establishing a point of common potential therefor and placing one of said sections in phase opposition to the remaining sections, conductor means connected to the other end of said coil section connected in phase opposition for connection with one side of a plurality of individual loads, individual conductor means connected to the other ends of said coil sections of like phase sequence for connecting said sections to the opposite side of said individual loads, and means operatively associated with said transformer core for diverting a portion of the magnetic flux interlinking said transformer primary and secondary winding coil sections in accordance with fluctuations in said loads.

5. In electrical transformer apparatus of the class described, in combination, a transformer core, a primary winding linking said core, a secondary winding having a multiplicity of coil sections linking said core, conductor means interconnecting one end of each of said secondary winding coil sections establishing a point of common potential therefor and placing one of said sections in phase opposition to the remaining sections, conductor means connected to the other end of said coil section connected in phase opposition for connection with one side of a plurality of individual loads, individual conductor means connected to the other ends of said coil sections of like phase sequence for connecting said sections to the opposite side of said individual loads, and a plurality of auxiliary magnetic core sections corresponding to said coil sections of like phase sequence operatively associated with said transformer core respectively embracing each of said coil sections for individually controlling the inductive reactance of each of said coil sections in accordance with individual fluctuations in said loads.

6. In electrical transformer apparatus of the class described, in combination, a transformer core, a primary winding linking said core, a secondary winding having a multiplicity of coil sections linking said Core, conductor means interconnecting one end of each of said secondary inding coil sections establishing a point of com mon potential therefor and placing one of said sections in phase opposition to the remaining sections, conductor means connected to the other end of said coil section connected in phase op position for connection with one side of a plurality of individual loads, individual conductor means connected to the other ends of said coil sections of like phase sequence for connecting said sections to the opposite side of said individual loads, magnetic core shunt means interposed between said transformer primary winding and said transformer secondary winding for uniformly altering the magnetic flux interlinking said primary and secondary windings in accordance with fluctuations in said loads, and a plurality of auxiliary magnetic core sections corresponding to said coil sections of like phase sequence operatively associated with said transformer core respectively embracing each of said coil sections for individually controlling the inductive reactance of each of said coil sections in accordance with individual fluctuations in said loads.

7. In electrical transformer apparatus of the class described, in' combination, a transformer core, a primary winding linking said core, a secondary winding having a multiplicity of coil sections linking said core, conductor means interconnecting one end of each of said secondary winding coil sections establishing a point of common potential therefor and placing one of said sections in phase opposition to the remaining sections, conductor'means connected to the other end of said coil section connected in phase opposition for connection with one side of a plurality of individual loads, individual conductor means connected to the other ends of said coll sections of like phase sequence for connecting said sections to the opposite side of said individual loads, magnetic core shunt means embracing said transformer primary winding and said transformer secondary winding coil section of opposed phase sequence for maintaining a relatively high magnetic flux linkage between said primary winding and said secondary winding coil section of opposed phase sequence in spite of fluctuations in said loads, and a plurality of auxiliary magnetic core sections corresponding to said coil sections of like phase sequence operatively associated with said transformer core respectively embracing each of said coil sections for individually controlling the inductive reactance of each of said coil sections in accordance with individual fluctuations 35 tions, conductor means connected to the other end 4 of said coil section connected in phase opposition for connection with one side of a plurality of individual loads, individual conductor means connected to the other ends of said coil sections of like phase sequence for connecting said sections to the opposite side of said individual loads, auxiliary magnetic core means interlinking said secr:ndary winding coil section of opposed phase sequence for controlling the inductive reactance of said coil section in accordance with collective fluctuations in said loads, and a plurality of auxiliary magnetic core sections corresponding to said coil sections of like phase sequence operatively associated with said transformer core respectively embracing each of said coil sections for individually controlling the inductive reactance of each of said coil sections in accordance with individual fluctuations in said loads.

9. In electrical transformerapparatus of the class described, in combination, a transformer core, a primary winding linking said core, a sec ondary winding having a multiplicity of coil sections linking said core, conductor means intercom necting one end of each of said secondary Winding coil sections establishing a point of common potential therefor and placing one of said sections in phase opposition to the remaining sections, conductor means connected to the other end of said coil section` connected in phase opposition for 75 connection with one side of a plurality of individual loads, individual conductor means connected to the other ends of said coil sections of like phase sequence for connecting said sections to the opposite side of said individual loads, and a plurality of auxiliary magnetic cores corresponding to said secondary winding coil sectlons'of like phase sequence spaced from said transformer core and electrically insulated therefrom respectively interlinking said coil sections for controlling the inductive reactance of said sections in accordance with fluctuations in said loads.

10. In single phase electrical systems of the character described, in combination, a source of single phase alternating current electrical energy, a transformer having a primary winding and a secondary winding comprising a plurality of individual coil sections mounted on a common section of transformer core, means connecting the primary winding of said transformer to said source, conductor means interconnecting one end of each of said transformer secondary winding coil sections placing one of said coil sections in phase opposition to said remaining coil sections, a plurality of devices having negative electrical resistance characteristics corresponding to the number of said coil sections of like phase sequence, conductor means connecting theother end of said transformer secondary winding coil sections connected in phase opposition to one end of each of said devices, and conductor means connecting the opposite ends of said respective devices to the other ends of said transformer secondary winding coil sections of like phase sequence.

l1. In electrical transformer apparatus of the class described, in combination, a transformer core, a primary winding mounted on said core, a multiplicity of secondary winding coil sections mounted on a common section of said transformer core, conductor means interconnecting one end of each of said secondary winding coil sections establishing a point of common potential therefor and placing one of said sections in phase opposition to the remaining sections, conductor means connected to the other end of said coil section connected in phase opposition for con- 20 nection with one side of a plurality of individual loads, and individual conductor means connected to the other ends of said coil sections of like phase sequence for connecting said sections to the opposite side of said individual loads.

CHARLES P. BOUCHER.

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