US2788469A

US2788469A - Apparatus for igniting and operating gaseous discharge devices

Info

Publication number: US2788469A
Application number: US223070A
Authority: US
Inventors: Albert E Feinberg
Original assignee: Advance Transformer Co
Current assignee: Advance Transformer Co
Priority date: 1951-04-26
Filing date: 1951-04-26
Publication date: 1957-04-09
Anticipated expiration: 1974-04-09

Description

Apl'll 9, 1957 A. E. FEINBERG 2,738,469

APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES Filed April 26, 1951 t 2 Sheets-Sheet 1 pa e 72w 1.24 ez'laieg April 9, 1957 A. E. FEINBERG 2,788,469

APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES Filed April 26, 1951 2 Sheets-Sheet 2 x n .OQ'OQQ'. 0...... 66666666 r "i 3 L Z5- 22km? W P Y 51 21 j 22 .v.v.. .v.v. P 5 Y Y United States Patent O APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES Albert E. Feinberg, Chicago, Ill., assignor to Advance Transformer Co., Chicago, Ill., a corporation of Illinois Application April 26, 1951, Serial No. 223,070 13 Claims. (Cl. 315-138) This invention relates generally to apparatus for supplying the ignition voltage for a pair of gaseous discharge devices, and for providing operating voltage with suit able regulation for the devices subsequent to the ignition thereof; t V

The invention is "a modification of the invention described and claimed in my co-pending application Serial No. 135,669, filed December 29, 1949, and entitled Apparatus for Starting and Operating Gaseous Discharge Devices, n-ow Patent No. 2,558,293, dated June 26, 1951. In that application I described apparatus for use principally with the so-called instant start type of gaseous discharge device which requires relatively high voltage to ignite the same. Such apparatus transforms the voltage obtained from a relatively low voltage source to a relatively high ignition voltage, and, by virtue of the novel arrangement thereof, ignites the devices seriatim, that is to say, one after the other. This function is achieved by means, among other things, of an auxiliary starting secondary winding S1 which provides very high leakage reactance due to its loose coupling with the other windings of the apparatus.

The apparatus is especially intended for use in connection with the ignition and operation of fluorescent lamps, serving as the ballast for a plurality of such lamps. The device described in my copending application above referred to is characterized by a three-winding transformer on an elongate shell core, the windings consisting of a primary P, a first secondary S1 which has been mentioned above, and a second secondary S2. The windings are connected end to end in the order named, although physically placed upon the core with the primary P in the center, and various shunts and air gaps arranged to give rise to the desired characteristics. Generally, it can be said that the primary P and the first secondary S have a much looser coupling than the primary P and the second secondary S2. One lamp is connected across the combined primary P and secondary S1 and in series with a condenser, while the other lamp is connected across the combined secondary S1 and secondary S2. In another example of the same apparatus, the lamp and series condenser are connected only across the secondary S1, while the second lamp is connected across all three windings. One of the essential features of the described apparatus is that the secondaries are in voltage bucking relationship.

In operation, when power is applied to the primary of either of the above described circuits, a voltage is generated in the secondary S1 which is sufficient, either combined with the primary voltage in one case, or alone, as in the second case, to ignite the first lamp which is in series with the condenser. When current flows in this lamp, there is an out of phase voltage set up in the secondary S1 which now combines with the voltage of S2, and in the case of the second described apparatus, with the voltage of the primary P in addition, to provide igniting voltage for the second lamp. The high impedance of the secondary S1 opposes the flow of current therethrough so that very little current will take the path through that winding. Thus, the circuit during operation acts as a series circuit.

2,788,469 Patented Apr. 9, 1957 The current through the winding S1 being very low, it has been possible to utilize a physical winding whose number of turns is very great while the gauge of wire is very small. Thus, with a very small ballast, high ignition voltages easily can be achieved without considering the problems of high current flow through the winding S1.

it has been found that the above described circuit of my copending application will operate satisfactorily for a large variety of discharge devices. For example, excellent results have been obtained when same is used with lamps known as 40 watt, T12, forty eight inch fluorescent lamps having an ignition voltage of approximately 450 and an operating voltage of 109 volts; with watt, 96 inch T-l2 lamps which ignite at about 625 volts and operate at about volts; and with many other lamps whose operating current is substantially less than 425 milliamperes and of the order of 200 milliamperes. The former value of current i.e. 425 milliamperes is for 96" T-8 lamps which operate at 285 volts. As for these discharge devices, the circuit of the co-pending application can be made eiiiciently to operate by varying the circuit constants in accordance with the teachings of the said disclosure, but in certain applications the expense and size of the ballast may be unnecessarily increased.

The problem which becomes manifest arises by virtue of the fact that the primary voltage in the greater majority of commercial applications of the device is of the order of 118 volts A. C. This places a limitation upon the physical constants of the apparatus, and prevents a certain amount of flexibility of construction which could be achieved for varying conditions if the primary voltage could be more conveniently chosen. When the discharge devices have high operating voltages, the. current which passes through the winding S1 increases. Under these circumstances, and considering that the device is formed of a pair of lamp circuits in parallel and having a common leg S1, the impedance in each branch will certainly not be the same. So the current will not evenly divide in the branches, and one lamp will be operating at a greatly diflerent current than the other; Obviously, both lamps under these circumstances are not operating at rated wattage. The eflect upon lamp life and lighting efficiency becomes very important. On the deficient lamp, the light output will be decreased, and upon the lamp with more than rated current, the life will be decreased.

The principal object of the invention is therefore to provide a balanced circuit of the character described in which both lamps willbe operating at substantially the same wattage.

in addition to the above, while not totally essential, in

' certain cases this balance can be achieved. with a coincidental decrease in the current flowing through the secondary S1 and an ancillary object of the invention is the pro- VlSiOn of apparatus of the character described in which this current is kept low.

Other objects of the invention are to provide apparatus which is capable of providing high ignition voltage and subsequent high operating voltage for gaseous discharge devices connected to ignite seriatim and operate substantially as series connected devices, such apparatus being constructed in various manners including additional windmgs, or in other cases, tapped connections whereby the desired voltage balance in the gaseous discharge devices is achieved.

Other objects will become apparent as: a description of the invention is set forth hereinafter, in which I have shown and described ballasts for gaseous discharge devices which are constructed and operate in accordance with my invention. Such detailed to assist in an understanding of the invention and are not by way of limitation, since it is intended that the description and illustrations are claims shall determine the extent and scope of the invention; Obviously many variations are possible within the 1 purview of the invention.

Figs.-4, 5; 6'and-7 are similar viewsofmodified forms of the apparatus of the invention,

Figs. 8'and 9 are diagrammatic views oftheclectrical circuit of the invention shown and describedin the above referred to copending application,

Basically the invention consists ofadding anin phase component to the circuit ofthe gaseous discharge device which is vaifected by thecurrent unbalance in the starting secondary. This is done by providing a third secondary winding 53 which is. arranged in close coupled relationship to a source of voltage substantially of the same phase as the voltage of the discharge device, and connecting'said winding in the circuit of the device, although in voltage opposition thereto.

In order to render this explanation clear, I have illustrated in Figs. 8 and 9 the circuits of the invention. of the copending application referred 'to above It will be seen that in each there is a primary P, a secondary;S1, and a The windings are connected end to end,

secondary S2. forming

junctions

29 and 21. The primary is connected across the

line terminals

22 and 23 from which it is energized by suitable A. C. power. One gaseous discharge device, consisting of a lamp 24 is connected fromterminal 22 to juncture 21 by leads25 and 26. There is a series condenser 27 in the lead' 26. A second fluorescent lamp 28 is connected from the free -end of winding 82. V to the juncture 20 .by the leads. 29 and 30. Obviously the lead 30, terminal 23, and juncture 30 are ,all at the same potential.

As explained, the windings S1 andSz are in'voltage 0pposition arrangement, and in this instaneetheprimarysl? is in. voltage additive-relation to the starting-secondary.

S1. The operation of this apparatus ;is as explainedsherein and in said copending application;

The apparatus illustrated in; Fig.1 .9 is also: shown, de-

scribed, and claimedsin said copending application asamodified form of the preferred embodiment. The only diiference between it and the apparatus of Fig. 9 is that the lamp 24 is connected in this case across the juncture 20and' 21 so that for startingall. of the voltage for the lamp must be developed in secondary .81. After ignition of lamp 24, the component of voltage. developed in Si which is in phase with the voltage of Szcoinbines also with the primary voltage to assist in ,ignitingthe second lamp 28. As in thecase of Fig. 8, the primary P, first secondary S1, and second secondary S2 areconnected end-to I end. by means of junctures 20..and.21, the-primary P is connected toline terminals Hand 23;- The lamp 2% is, however, connected by. leads 29 and-'30across allof the windings together, that is, frornterminal 2210 the free endyofwinding S2. The operationof this apparatus. is substantially the same as that of Fig. 8.

It is to be noted that none of the symbols relating. to iron cores have been usedin order that the circuit diagrams be simple, but obviouslysuch cores are present.

Theapparatus of the instant inyention has substantially the same mechanical construction features asthat of the-.

copending-application. lnFigs. l and.2 -I have illustrated the construction of transformers embodying the circuits of the invention. a transformer 4t) which comprises an iron core formed as a rectangular shell 41 made up of electrical laminations and maintained in assembled. condition by any suitable clamps or rivets (not shown); The shell 41 is elongate and'has three windows formed, therein alongthelength thereof for housing three windings 43, M and 45. The windings fill the entire respective windows and hence the figure cannot show. the. windows. Thewindings. are mounted upon a central winding leg 45 which is also laminated and the endsof which are adapted matingly to seat in the shell 41. Thus, the right hand end of the winding leg 46 has a convex formation and the shell end has a concave seat to receive the same inintimate fit resulting in the joint illustrated at 47. The left handend of the.

winding leg 46 may. beeprovided. with aprotruding. tip adapted to engage. anotch in a joint. illustratedat 48.

The recess for the left end may have sufiicient depthto,

46 andthe shuntextensions. A larger shunt 54-is formed between coils.44wand-,45 and having gaps 55 between the winding leg 46- and, the. shunt extensions thereat. In any event itcan be-seen that the coupling between the coil 45 and athe coil 44' is much less than that between the coils 43 -and 44-. The-end-gap 50 and the shunt52 are means for improving wave shape.

The construction illustrated in Fig. 2 is a modification ofthatillustrated in Fig. 1. substantiallythe same as transformer 40 except-that the end gap 50 has been eliminated and the coupling between coils 43'and 44.increased; by eliminating the shunt 52;-

The circuits-to be described in: detail are capable of beingusedin connection with either of the transformer constructions described above. The designation. coil has been used since, depending upon the vparticular. circuit, the coilsof Figs. land 2 may represent'more than one winding. Throughout the figures, the-auxiliary starting secondary Sris always represented by the coil 45; Theprimarywinding? is always similarly positioned and may .be'represented by the'coil 44; but in: certain modified forms of the invention the coilr44 Will representthe primary windingland a;third secondary windingqsiwound upon-thepr-imary P, or at least quiteclosely coupled theretoin the-,same-window; The coil 43, usuallyrepresents the secondary winding S2, but in one form-it also represents Ssand. in another form;, it represents Sz with a tap.

Attention is now-invited to Fig. .3. ofithe drawings in which. I have illustrateda circuit embodying my invention. The same general arrangement of parts is used here as in the case of thatcircuit illustrated .inFig. 8,. except that the lead 26:between the condenser; 2 '7 and the junc-v ture- 21 has beenopenedand a third secondary S has been inserted. in series .with thecondenser 27 and-dischargedevicel ih Thus, thewindingsP, S1, and S2 areconnecfted end. to end with the juncturcs 20 and 21.be: tween them, and the primary Pf beingconnected. to -,the

line terminals

22 and 23. The lamp 28 is connected from the free end of winding S2 to the juncture 20 by leads 29 andfit) respectively. Again, lead 30,juncture20'and terminal 23 are --at the same potential. The lead 25connects the terminal 22 to-the left hand side of the lamp 24;

while the right handside-of the lamp-is connected by lead 26 to the series condenser 27 which in turn is connected to thethirdsecondary 'Sa. and thence to juncture 21.

The thirdsecondary.winding S3 is closelycoupled withthe primaiyP, andis connectedin. additive voltage relationship with the other windings s of, .the .closed circuit in cluding the lamp 24, primary P, first secondary:S1;and.

Referring to Fig. 1', there is illustrated Thus the transformer is.

arssigea condenser 27. Therefore it. is in voltage oppositionto the voltage across the lamp 24 during steady state opera tion. The arrows throughout the figures of the drawings indicate the voltage sense of the pertinent winding.

If we consider the circuit of the lamp 28, which is a closed circuit including lamp 28, second secondary S2 and the secondary 81 we will note that the two lamp circuits are apparently connected in parallel and having a common leg which is the starting secondary S1. Examining the elements around the respective circuits, it will be seen that their characteristics will be different. For example, the first mentioned circuit includes a condenser, a high impedance winding S1 and the primary P (not considering for the moment the winding S3). The other circuit has only the two windings S1 and S2. If S1 is a voltage source, and the current passing through the winding is intended to divide, it is almost impossible that the same division will occur when transformer of Fig; 3 is serving 400 ma. lamps operating 109 or 185 volts as will occur when it is serving 200 ma. lamps operating at 385 volts the primary voltage being substantially the same in in both cases. l

I have found that if I add the secondary winding S3 in the manner shown, the current of S1 will be divided fairly evenly between the two lamps so that both are operating substantially at their rated wattage and hence at their maximum efficiency. The winding S3 functions to obtain an in-phase voltage component from the primary P to supply the lamp 24. The voltage of S1 is principally utilized in balancing the leading voltage across the condenser 2'7 and very little remains as a component in phase with voltage of P to balance. the in-phase voltage of the lamp 234. This being suiiicient when the difference between line voltage and lamp voltage is not great, under such circumstances, the circuit of Fig. 8 is satisfactory to handle lamp operating voltages up to 195 voltswhen the primary is of the order of 118 volts. In the case of Fig. 9, no difiiculty is experienced under the same circumstances. For higher voltages, however, there is insuificient voltage in the circuit of lamp 24 and whatever current is flowing in S1 is divided unevenly. The lamp 2% may receive more than its share, while the lamp 24 will receive less. The added winding S3 alleviates this effect.

It has been found that the addition of the winding S3 may serve to increase the flow of current in S1 but if the lamps are both operating at rated wattage, the series circuit effect is achieved and the small increase in current of S1 is not harmful. In certain cases where transformers designed for operation in accordance with the circuit of Figs. 8 and 9 were modified to operate in accordance with the teachings of this invention and at higher lamp voltages, the current flowing in S1 was still so very low when compared with lamp current that the desired feature, namely a large number of windings of small gauge wire, could still be used.

In Fig. 4 I have shown a modification of the circuit of Fig. 9 to operate in accordance with my present invention. Again, as in the case of Fig. 3, into the lead 26 I have inserted a. winding S which is closely coupled with primary P in order to acquire a voltage by transformation therefrom to help operate the lamp 24. In this case, prior to the addition of the winding $3, the entire in-phase voltage component for lamp 24 was required to be obtained from the winding S1. The operation of this circuit is believed obvious from what has been set forth above.

in Fig. 5 I have shown another modified form of my invention based upon the circuit of Fig. 8. The winding 33 is actually a part of winding S1 because from a voltage stand-point it is in series with S1. The added voltage component gives rise to the voltage balance desired.

In Fig. 6 there is illustrated another form of the invention. In this case, the winding 53 is a part of the winding S1 since it is in series therewith, but the in-phase voltage component is not transformed from, the primary P but from the secondary S2. Therefore the winding S3 is wound on the winding S2 or at least in the same window, and the two windings together would be represented in Figs. 1 and 2 by the coil 43. During operation the Winding Sz carries a current which is leading relative to the primary but its flux is practically in phase with the primary flux. Therefore, there will be a relatively large inphase component available for transformation to S3 and for use subsequently in balancing the circuit of lamp 24. The existence of this large iii-phase component of flux in winding S2 usually provides a sulficient voltage for.

proper operation of the lamp 28.

In Fig. 7, which is, still another form of the invention based upon the circuit of Fig. 8, a part of the in-phase voltage of the winding S2 can be obtained for use in balancing the voltages in the circuit of the lamp 24 by connecting the right hand end of the winding S1 to a tap 61 of the winding S2.

Practical examples of the above described apparatus have been constructed and successfully tested, using as physical constants those of the examples given in the copending application above referred to. The deter mination of the characteristics of the winding S3 or of the location of the tap 61 is a relatively simple matter. The iii-phase component to produce rated lamp current in a given loop should approximate the in-phase operating voltage of the lamp, or other gaseous discharge device. It should be recalled that the total voltage across a gaseous discharge device is the resultant of a component substantially in phase with the voltage of the primary, and an inductive component. For example, a 96 inch T-S fluroescent lamp, with a wattage rating of 49 watts, and operating at a current of 200 milliamperes will have a resultant operating voltage drop of 285 volts and an in-phase voltage drop of 245 volts. The desired iii-phase voltage in series with S1 should be of the order of 245 volts (or slightly more since the voltage across the lamp is nonsinusoidal). This voltage can be obtained by simple computation of turns ratio required of a voltage to be produced by S3 which when added to the in-phase voltage of P will give the desired value. Simple experimentation can aid in determining the desired characteristics of S3 for a given set of circumstances.

It was found in the above mentioned fluorescent lamps, i. e., 96 inch T-8 lamps passing 200 milliamperes of current, that when the primary P alone was in the loop with S1 the current unbalance i. e., the difference between the currents passing through

lamps

24 and 28 was from 30 to 50 milliampcres, or a percentage of approxi mately 20. This is the circuit of Fig. 8. In the case of Fig. 9, the unbalance was from 50 to milliarnperes. With the addition of the secondary S3 as in Fig. 3, of a value so that the sum of the in-phase voltages of P and S3 approximated that of the lamp 24, the unbalance was reduced to from 10 to 28 milliamperes, or well within commercial tolerances.

The teachings of my invention have been set forth in a manner which may have inferred the operation of the apparatus being based upon certain theories or electrical principles. While I have attempted to show some logical reasoning for the operation of the circuits, it is not my desire to be limited thereby. These theories have been advanced only to aid in the understanding of the invention. It is known among those skilled in the art of ballasts and transformers for gaseous discharge devices that the exact nature of the phenomena produced is highly complex, and not too well understood by reason especially of the non-sinusoidal nature of the currents and voltages, by the peculiar interreaction between the windings and the magnetic circuit, and the effects of the negative resistance of the gaseous discharge devices. I have discovered that the desired results described herein are achieved by the constructions set forth, and the exact explanation of why such results are achieved is immaterial.

zyr-ssaaw Substantialv increase; in: the inductanceof" the loopsmayz-solimit starting current throughSras to decrease the. life:v of; the fluorescent tubes through ion-bombardment of the filaments while cold. Therefore, the use of devices such as separate chokes to achieve balance; besides being expensive and increasing total ballast weight, could cause harmful ettects upon the'lamps being served.

It will be seen that l. have provided apparatus in which. all of the advantages of the inventionof my copendingapplication have been achieved; and in addition I have enabled the same to be used where the operating voltages of the lamps is many times greater than the voltage of the source. I have provided means for counteracting the unbalance which may arise under such circumstances by reason of the currentfrom the-winding Srdivi'din-g unequally between the lamp circuits and subjecting one-lamp of-the'circuit-including the winding S2 to abnormal wattages.

It is believed that the invention has sufficiently been explainedto obviate additional details, and it'should be appreciatedthatthe circuits are capable ofwidcvariation in their elements andminor details'withoutdeparting from the spirit or scope of the invcntion'as defined by the appended 7 claims.

What! desire to secure by Letters Patent of the United States is:

1. Apparatus of the character described comprising a pair of gaseous discharge devices, a source of'A. C. voltage greater than the igniting voltage of the devices, an elongate iron core transformer having a primary winding providing a common source fiux for all parts of the core, a first secondary winding, and a second secondary winding, each winding having: first and second end terminals, the primary Winding being physically located in the center of the core between the ends thereof and thefirst and second secondary windings being mounted on opposite sides thereof but the first secondary winding being much looser coupled to the primary winding whereby to' provide high leakage reactance during operation and having reverse open circuit voltage relationship to thevoltage. of the second secondary winding, a third secondary winding also having first and second end terminals and closely coupled with one of said primary and second secondary windings whereby to have induced therein a "oltage substantially in-phase with thevoltage of said one of said windings, the terminals of the primary winding being connectedacross the source, a condenser, an electrical path comprising the first of said gaseous discharge devices in series withsaid condenser and'the first and third secondary windings and said'path being elec-- trically connected to the first terminal of said second secondary winding, the first and third secondary windings being in additive open circuit voltage relationship, in said loop, the said path being closed to a loop at one of the first and second terminals of the said primary winding, whereby upon ignition at least the voltage of. the first and third secondary windings will appear across the said first gaseous discharge device, the second gaseous discharge device being connected from the secondterminal of said. second secondary winding to the other of the end terminals of the primary winding.

2.. Apparatus as claimed in claim 1 in which the loop includes the primary winding so that upon ignition the first gaseous discharge device is connected etfectivcly across the primary, first and third secondary windings and the second gaseous discharge deviceis connected across at least the first and second secondary windings but excluding the primary winding.

3. Apparatus as claimed in claim 1 in whichthe loop excludes the primary winding so that upon ignition the first gaseous discharge device is connected effectively across only the first and thirdsecondary windings, and the second gaseous discharge device is connectedacross at least the firstand second-secondary windings andtlre primary winding.

4..Apparatus as. claimed*inclaim 1 in-which the loop excludes:the primary winding=-and the third secondary winding has a terminal-in common with-the second terminal ofithe'first secondary winding and the first terminal of the second secondary winding, whereby the second gaseous discharge device is connectedonly across the primary, first and second secondary windings, the circuit. afterignition and during operation comprising a substantially series circuit across the primary winding and inclnding the two gaseousdischarge devices and the condenser and thesecond and third secondary windings all in series, with the first secondary winding by-passed.

5. Apparatus as claimed {in claim-4 in which the third secondary; winding is closely coupled with the primary winding.

6. Apparatus as claimed in claim 1 in-which the third secondary windinghas' a terminal in common with the second terminal of the'firstsecondary winding and the first terminal of thesecond secondary Winding, whereby the seeond gaseousdischarge device is connected across windingswhich excludesaid' third secondary Winding, the circuit after ignition and during operation comprising a substantially series circuit across the primary winding and includingthe two gaseous discharge devices and the condenser and the second and third secondary windings allin-series, with the firstsecondary winding lay-passed.

7. Apparatus asclaimed in claim 6 in which the third secondary winding is closely coupled to the primary winding.-

S. Apparatus as claimed in-claim fi in which the third secondary winding is closely coupled to the second secondary winding.

9. Apparatus'as claimedin claim 2 in which the third secondary winding has a terminal in common with the second terminal of the first secondary winding and the first 'terminal'of the second secondary'winding, whereby the second gaseous discharge device is connected across only the first and second secondary windings connected as in seriesvoltage-wiseg to the exclusion of the third secondary winding, the circuit-after ignition and during operation comprising a substantially series circuit across the primary winding and including the two gaseous discharge devices and the condenser and the second and third secondary windings all inseries with the first secondary winding by-passed.

10. Apparatus as claimedin' claim 1 in which that portion of the loop including the first and third secondary windingsin series is connected from the first terminal of the second. secondary winding to the second terminal of the primary winding, whereby the first and third secondary windings willboth be by-passed during operation of the apparatus.

11. Apparatus as claimed inclaim 10 in which the third secondary winding is closely coupled to the primary winding.

12; Apparatus as claimed in claim 10 in which the third secondary winding is closely coupled to the second secondary winding.

13. Apparatus as claimed in claim 2 in which that portion of the loop including the first and third secondary windings in series is connected from the first terminal of the second secondary winding to the second terminal of the primary winding, whereby the first and third secondary windings will be by-passed during operation of the apparatus, and the second gaseous discharge device is connected across and subject to the voltages of all three secondary windings connected as in series voltagewise.

ReferencesCited in the file of this patent UNITED STATES PATENTS Kazebee Aug. 11,