US2861217A - Apparatus for igniting and operating gaseous discharge devices - Google Patents

Description

Nov. 18, 1958 A. E. FEINBERG 2,861,217

I APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES Filed Aug. 17. 1954 2 Sheets-Sheet l F'l L AH EMT wmnmcag IL .2. ll 1 1 Z g 19 2, 21 f7 :5 i F5 e i fw/vee g Nov. 18, 1958 A. E. FEINBERG APPARATUS FOR IGNITING AND OPERATING GASEOUS DISCHARGE DEVICES 2 Sheets-Sheet 2 Filed Aug. 17. 1954 NNN N O E:

N WN United States APPARATUS FOR IGNITIN G AND OPERATING GASEOUS DISCHARGE DEVICES Albert E. Feinberg, Chicago, Ill., assignor to Advance Transformer Co., Chicago, 111., a corporation of Illinois This invention relates generally to apparatus for startmg and operating gaseous discharge devices, and more particularly is concerned with such apparatus intended for use with fluorescent lamps for lighting.

In recent years fluorescent lighting has developed along lines intended to increase lighting elficiency from the standpoint of size of lamp and electrical requirements by way of quantity of copper and steel; to lengthen lamp life and keep operating temperatures low. Quite important has also been the problem of keeping line power factor close to unity. The first practical hot cathode fluorescent lamps used starters. The initial high voltage ignition pulse was obtained by breaking a circuit having current flowing through an inductance, and in some cases, transformation was used. The starter provided a short circuit path so that current initially flowed through the lamp filaments to produce clouds of electrons and thereby enable the ignition of the lamps. Once ignition occurred, the starter switched open by some means, and the lower operating voltage appeared across the lamps with current flowing from a hot spot on one cathode to another such spot on the other cathode. Such structures had various disadvantages. For example, a starter freezing closed permitted continuous flow of current through the filaments which were unable to carry continuous current and hence burned out. Starters also required additional connections and sockets, and frequent replacement. Faulty starters resulted in flickering lamps. Principally, there was a considerable wait between energizing the circuit and illumination.

Then came the so-called instant-start lamp with its leaky ballast. The lamps were constructed to utilize high voltages and were started by brute force there being a minimum of current flow prior to ignition. Once current commenced flowing, the leakage reactance of the ballast dropped the voltage to the operating value. This apparatus had disadvantages in that high voltages were used, and lamp life was relatively low because of the stresses to which the same was subjected.

More recently there has been developed the so-called rapid start lamp which does not start as quickly as the instant-start lamps, but which is certainly faster starting than starter-operated lamps. The rapid start lamp utilizes filaments in the lamp ends which not only carry current during starting, but which also carry current during operation. Through suitable construction not necessary to the description of this invention, there are no deleterious effects due to the constant flow of current. The voltages are less than those of the instant-start but still high.

In order to supply the current for the filaments it is necessary to have filament windings operating at relatively low voltages.

This invention is primarily concerned with apparatus for igniting and operating rapid-start fluorescent lamps, and hence the ballast which is utilized includes filament windings. High voltage lamps obviously require considerable voltage for ignition in the event that they are 2 connected in series. Rapid-start lamps have heretofore been connected for series-sequence, that is, seriatim, starting and in this way it is not necessary to apply a high voltage across two lamps connected in series, but the voltage is applied to the lamps one at a time. Thus, two lamps are connected in series across an auto-transformer having a primary and secondary winding and one of the lamps is shunted by a capacitor. I

Considering this type of circuit utilizing 96" T-12 lamps, 540 volts is applied to the lamps which ignite at about 275 volts. In order to acquire such starting voltages it is necessary that there be a great number of turns in the secondary which increases the reactance, making it difficult to correct for power factor.

This invention provides a series sequence circuit in which the open circuit voltages are decreased thereby making it much simpler to correct power factor.

It is accordingly an important object of the invention to provide apparatus for starting and operating gaseous discharge devices which will provide filament voltages for the devices and which will start the devices seriatim and thereafter operate the same in series at excellent power factor characteristics.

It is a further object of the invention to accomplish the ignition and operation of the device through the use of a sequence start circuit of novel structure which will have low open circuit voltage characteristics.

As an example of the application of the invention to the same type of lamps referred to above, through the use of the novel circuit of the invention, an open circuit voltage of the order of 425 volts is all that is required across the primary and secondary combined in order to achieve starting and proper operation. The lamps operate at volts each so that total drop across the lamps during operation is only 300 volts, in a series circuit.

As an added feature of the invention, for use in combination either with the circuit of the invention referred to above or in connection with the conventional series sequence start apparatus, means have been devised to increase themagnetizing current of the primary without in any way affecting the total reactance of the series circuit, as an aid in correcting power factor.

Many additional objects will occur to those skilled in this art, as a description of certain preferred embodiments et forth hereinafter is made. Diagrammatic illustrations of said embodiments serve as an aid to comprehension and explanation of the invention.

In the drawings, the same characters are used throughout the several figures to illustrate the same or equivalent parts.

Fig. l is a side elevational view of a transformer of conventional construction for use in connection with apparatus for igniting and operating so-called rapid start lamps through the use of a sequence start circuit of a known type.

Fig. l-A shows how the left hand end of the transformer of Fig. l is changed in accordance with the inven tion to provide a better power factor.

Fig. 2 is a circuit diagram of the conventional series sequence start apparatus capable of being used either with the prior art transformer of Fig. l or with the transformer of the invention illustrated in Fig. 1-A.

Fig. 3 is a circuit diagram of apparatus constructed in accordance With the invention in which the circuit has certain novel aspects.

Fig. 4 is a side elevational view of a transformer constructed in accordance with the invention and having the circuit of Fig. 3 associated therewith.

Fig. 4-A is a modified form of the transformer of Fig.4.

Fig. 5 is .a modified form of the circuit diagram of Patented Nov. 18, 1958,

d Fig. 4 which can be used in connection with the transformer either of Fig. 4 or 4-A.

The problems involved in providing ballasts for rapid star-Llamps are best.understood, andtheir solutionby means of this invention best emphasized through a preliminary studyand explanation of the prior art seriessequence startcircuit illustrated-in Figs. 1 and 2. In Fig. 221s in other figures throughout this specification the .usual lines used as symbols to designate iron cores have been. omitted for clarity.

The presently used series-sequence start ballast includes a-primary winding P, a secondary winding S loosely coupled therewith to provide a leaky transformation and high leakage reactance for ballasting operation. The primary P and secondary winding S are connected-in auto-transformer arrangement across a pair of lamps connected in series. In Fig. 2 the lamps are designated L -and L tintheorder of ignition. The left hand..terminal of the primary winding? is connected by lead to one side ofthe filament 11 of the lamp L and the right hand terminal of the primary winding P connects by Way of lead 13 with the left hand terminal of'thesecondary winding 3. The right hand terminal oflther secondary winding 5' is connected by lead 15 to one side of the right hand filament 17 of the lamp L The right hand filament 19 of the lamp L and the left hand filament-21 of the lampL are connected by leads 23and24. The primary winding P is connected across asourcev of A. C. voltage S of a value less than the ignition voltage of either lamp.

Thereis a condenser C across the lamp L connecting fromlead 15- to 23, and a second condenser C in series with. the-windings and lamps in the lead 15. The condenser C is the starting condenser, and the condenser C is the power factor condenser.

I: have described the basic circuit of the series-sequence ballast. The operation is simple. Energizing of the primary winding P induces a high voltage in the secondary winding S. The combined voltages appear across both lamps, ie. from lead 15 to lead 10, but since the condenser C has practically no'effect on the circuit and neither does the condenser C a relatively large voltage appears across the lamp L and it ignites. As soon as current commences to flow in the circuit, the voltage across C builds up to a point where it is sufficient to ignite lamp L Thereafter both lamps are supplied with current in series.

In order to provide current for the filaments 11, 17, Hand; 21, three filament windings F F and F are closely coupled with the primary P. Filament winding F connectsby leads and 31 across filament 11. Filament-windingF connects by leads 32 and 33 to leads 23 and 24 respectively and thereby provides current to filaments 19 and 21 in parallel. Obviously separate filament windings for filaments 19 and 21 can be used as will. be described in connection with Fig. 5. Filament winding F connects by leads 34 and 35 to filament 17 and supplies current thereto.

It is understood that in order for the lamps in series to operate properly there must be a resultant impedance in the operating circuit to ballast the lamps and prevent. their burning out due to their negative resistance characteristics. Accordingly the sum total of reactance due to the flow of current through the secondary S and primary P is inductive and it is desired to have a-capacitive reactance predominate so that if anything, the current drawn by the apparatus will be leading. Furthermore, leading power factor is more easily cor rectedas will be described. There must be sufficient excessof capacitive reactance in the circuit (after compensating for the inductive reactance) to give proper operatingcurrent for the lamps.

The total power factor can then be adjusted by drawing magnetizing current from the line, which is induc- 4 tive insofar as the line is concerned but has little effect upon the total impedance of the circuit. This is done as described in connection with Fig. 1.

There is illustrated a transformer having a laminated iron core 41 of shell construction and a central winding leg 42 formed of the same laminations so that when stacked the winding leg will matingly engage with the shellcore 41. The-elongated core has an abutting connection 43 between its l eft hand bridge end 45 and the left hand end of the winding leg 42. It has an air gap 47 between its right hand bridge end 48 and the right hand end of the winding leg42. There is a support point 50 on the right hand end ofthewinding leg 42 to size the gap 47. The gapmay be formed by shaving.

Two windows are formed at opposite ends of the shell core 41, and windings slipped over the winding leg 42 and properly positioned are adapted to be engaged and retained in said. windows. Thus there isfermedagwindow 52 which houses the winding P and. theg tilamentwind ings, which are preferably wound on top of windingP. There is also formed. awindow-54: which accommodates the winding 8.. There is .a shunt 56 formed. between the windows and hence. the windings -P;and .S which has -,air gaps 57.

T heshnnt 56 provides the leakage reactance which ,en ables the voltage to drop after starting, but ofconrse this has no effect upon open circuit voltage. Open circuit voltage will govern the number of .turns insecondary winding S, the higher the open circuit voltage-the greater being the numbervof turns. Obviously thegreater the number of turns, the higher will the total circuit reactance be and. the. more capacitive reactance is required to neutralize this reactance and providenthe. total reactance for ballasting. Thus C s value is governed byopen circuit voltage considerations.

Heretofore, it has beenltnown to provide a.;gap';47 Which causes magnetizing current to be drawn from the line, the effect of which is to adjust power factor because magnetizing current is inductively reactive. But-where the gap 47 is increased the leakage across shunt 56 is increased, the circuit leakage reactance;is increased,.and the capacitive reactance. may be inadequate for proper ballastor if increased, may seriously decrease total current flow through the lamps and hence lighting efficiency. The physical size of the primary and secondary windings are practically limited and. saturation efiects become important.

The.achievement of good power. factor is.-a--very difliculttask with the apparatus ofPigs. l andgZ, the'net result usually being acompromise.

I have found that one manner of solying the difT-iculty is .to provide a second: air gap 60 at theleft hand end of the winding leg 42- i n,place ofjthe joint.43. It may be of any type snchas, that illustrated in Figl-A and includinga-support point 62. ,Adjustment of this air gap enables the primary winding itself; todraw additional magnetizing currentwhich has little effect. upon the leakage reactance of the transformer, and practically no effects upon saturation in the vicinity of the secondary winding S or the t0tal.reactance of the circuit during operation. Thus gap 47 is adjusted for bestswave form and leakage reactance, and the remainder of compensation for excess of capacitive reactanceis achieved through adjustment of the gap 60.

Of course, theuse of-a gap adjacent the primary winding P has practically noefiect. upon the open circuit voltage. This is still high. The circuits and apparatus described hereinafter alleviate the difficulties of attempting to achieve proper operating current, proper starting voltage, and good line power factor-encountered in the use of the, apparatus of Figs. 1 and 2. Basically this is done by decreasing the open circuit voltage affecting the operating circuit.

In Fig. 3' there is illustratedaballastfor rapid start lamps which is mounted upon the transformer i1- lustrated in Fig. 4. There is a primary winding P, a first secondary winding S and a second secondary winding S The windings are connected end to end in the order named, with the winding S located between the others and forming therewith the junctions 71 and 72. One lamp L is connected across the first secondary winding S alone by leads 74 and 76 connected to one side of each of its filaments-11 and 19 respectively. There is a condenser C in the lead 74. The second lamp L is connected across all three windings together by means of the leads 78 and 80 connected respectively to one side of the filaments 21 and 17. The primary winding is connected across a source of A. C. voltage S of a value less than the igniting voltage of the lamps. Note that lead 74 connects to juncture 72 and one side of the source connects to juncture 71. Both leads 76 and 8d connect to the right hand terminal of the winding S and the lead 78 as well as the second side of the source are both connected to the left hand terminal of the primary winding P.

The instantaneous voltage sense of the windings is as indicated by the arrows VP, V8 and VS The secondary windings are in voltage opposition with respect to a loop containing both windings and defined by all three windings and the lamp L In the same loop, the primary and second secondary windings are in voltage additive relation.

There are three filament windings F F and F connected by leads 82, 83, 84, '85, 86 and 87 to the filaments in the lamps. These connections are easily traced from the drawing. The windings are wound on top of the primary.

As shown in Fig. 4 the windings are associated with a transformer 70 having an elongate shell core 91, a central winding leg 92 and windows 93, 94 and 95 housing the respective windings S and S There are shunts 98 and 99 between windings with gaps 1% and 101. The left hand end 102 of the central winding leg meets the core bridge end 103 in a mating joint 105 while the right hand end meets the core bridge end 105 in a gap 108 for the same purpose as the gap 47.

The operation of the device is somewhat as described in my Patent No. 2,558,293. Upon energization of the primary .winding P, high voltages are induced in the secondaries S and S Total voltage across lamp L is insufficient to ignite the lamp because of the bucking effect of the voltage of S but the voltage of S appearing as it does only across the lamp L is sufiicient in and of itself to ignite the lamp. First secondary winding S is formed of a large number of turns of very fine wire because after ignition of the lamp L practically no current flows through this winding. Once current flows through S there is a quadrature voltage component additive to the voltages of S and -P so that now, after ignition of L there is sufficient voltage across lamp L to ignite it. After ignition, and because of the isolation of the winding S through the use of the shunt 98, very high leakage reactance forces the major flow of current to be through the lamps and secondary winding S in series, substantially lay-passing the winding S The open circuit voltage occurring across the principal windings in the operating circuit (which governs the total reactance of the circuit) is very low. Hence, S is formed of a small number of turns, and the value of C need not be very great. The magnetizing current required of the line can much easier be obtained by adjustment of the gap 108 and the desired balance easily reached. I have also found that additional magnetizing current can be drawn through the addition of a gap 110 at the left hand end of the core as shown in Fig. 4A if required without causing any difiiculties. It will be noted that there is never a problem of too little inductive reactance in 5 because even the minute current in S through the large number of turns provides a flexible method of adjusting total circuit inductive reactance.

Fig. 5 is an illustration of amodified form of the circuit of Fig. 3.

In this circuit, the lamps L and L are respectively connected across the primary and first secondary windings combined and across the secondaries combined. In other words, the left'hand terminal of the primary winding P is connected by lead to one .side of the filament 11 of the lamp L while its right hand terminal and the left hand terminal of the winding S meet to form junction 71. The right hand terminal of the first secondary winding S meets the left hand terminal of the second secondary winding S in the junction and this junction is connected by the lead 121 to one side of the filament 19 of the lamp L The capacitor C is in series with the lamp L Note that the primary winding is connected across a source S of A. C. voltage less than the igniting voltage of either of the lamps. The right hand terminal of the second secondary winding S is connected by lead 122 to one side of the filament 17 of the lamp' L while the junction '71 is connected by the lead 123 to the other filament 21.

Note that the windings are connected one after the other, i. e., end to end with the first secondary winding S between the other two and common to both lamp loops. The secondary windings have their instantaneous voltages buckingthat is to say, on open circuit V8 and VS are opposed. The instantaneous open circuit voltage sense of the primary winding P reenforces the voltage of S The primary voltage sense is indicated by the arrow VP. Because of this the voltages which occur at open circuit are very low. Especially the voltages which are expected to be obtained from P and from S This means that the number of turns is low and the reactance during operation is also low.

There are four filament windings F F F and F all wound on top of the primary winding P and in the same window, it being practical to use the transformer illustrated in Figs. 4 and 4A for mounting the windings of this modified form. These filament windings provide constant current flow through the filaments of the lamps and provide the initial cloud of electrons necessary to start the lamps, as Well as emission during operation to keep operating voltages low and the discharge stable. Filament windings are connected as follows: F by leads 131 and 132 to filament 11; F by leads 133 and 134 to filament 19; F by leads 135 and 136 to filament 17; and F by leads 137 and 138 to filament 21. It will be seen that each filament has its separate winding, instead of using one winding for two filaments as illustrated in other embodiments.

Operation of the apparatus is as described in the patent hereinabove referred to. The starting voltage produced across the lamp L by the combined primary winding voltage and first secondary voltage is high enough to ignite the lamp L The initial voltage appearing across the lamp L is very low and certainly too low to ignite the lamp because the voltages of the two windings across which the lamp L is connected are opposed. S is a very high voltage winding made upof a large number of turns of fine wire. Once lamp L has ignited there will be a flow of current in the winding S and the resulting voltage is so changed in reactive character as to provide a quadrature component which now reenforces the voltage of the winding S and raises the same an amount sufficient to cause ignition of the lamp L Thereafter, with both lamps lit, the reactance of the winding S is so great, especially because of the large shunt between it and the remainder of the windings, that current flows in substantially a series circuit through the lamps and the second secondary winding S The power factor is controlled by the condenser C and the side of the end gap 108. The inductive reactance of the winding S has no adverse effect upon the ease of adjustment of power factor because of the extremely low current flowing in the winding during operation.

It has been found that the use of filament windings in combination. with circuits 'of.- the .=type illustrated. in Figs. 3 to 5 do not raise the same problems asin. other series sequence start circuits,:because, since the: basic operating circuits have so little inductive reactance, the additional drain of current is not important. In a circuit wherethe reactance of necessity caused by reason of initially required high open circuit voltages is. alsohigh, and adjustmenttor power factor is diflicult, even the added drain-from the primary of filament windings increases the difficulty of balance. In this invention, as described in connection with Figs. 3 to 5 because of the lowopen-circuit voltages, filament windings are no problem atall.

It -is feltthat the invention has been fully described and setforth. hereinabove such that=one skilled in the ballastart couldconstructthestructures and practice the invention. This is especially true in view of the well-known characteristicsand the widespread usage of the circuits of thepatentuhereinabove referred to.

I claim:

1. Apparatus for igniting and operating rapid start tluorescenttlighting devices with suitable regulation after operation commences; whichv comprises, a pair of rapid startdeviceseach having end filaments, a source of A. C. voltageofrelatively low value, an elongate iron core shell of rectangular structure and having end bridging portions, a central winding leg matingly engaged between the end. bridging portions and having -a-transformer formed-Lot primary, first secondary, and second secondary windingsrnounted thereon, thewindings being physically separated by high reluctance magnetic shunts, the primary being betweenthe other two windings, and an end gap between the winding leg-and the bridging portion adjacent the second secondary winding, a plurality of filament windings. alllmountedin closecoupled relation to the primarywinding and connectedfto the filaments to continuously energize the same, the primary and. secondary windings beingconnected end to end, with the secondaries bucking one another considering an open circuit loop containing the primaryand both. secondary windings in series, a condenser in series with one device, and together therewith connected across a part of the transformer excluding the second secondary winding but including atle'ast the first secondary winding, the second device being. connected across a part of the transformer including at .least both. secondary windings.

2.1Apparatus as described in claim 1 inwhich there is another and gap between. the windingzleg and the opposite bridgingportionadjacent the firstsecondary winding.

3; Apparatusfor igniting and operating gaseous dischargedevices with suitable regulation which comprises a.pair=of.- gaseous discharge devices having filaments in oppositeends thereof, a source of A. C. voltage of value lessthan the igniting voltage of either device, an elongateferromagnetic core of shell type having a central win-ding: leg therein, ,a. transformer comprisinga primary winding and. twosecondary windings. said. primary winds ing connected acrosslthe source, therwingjiugsibeingt COIL- nected end to .end with the connection betweeni secondaries providing a junction,v and the-\secondariesebeing.in.open; circuit voltage opposed; relationship with respecttoa loop,

containing, all windings, theprimary and;secondar y,wind ings being mounted on saidwinding, leg. with the primary winding in the center andlhigh reluctanceshunts between it and the other t-wo windings,,a lead extending from said junction to one, side of a filament ofthe first of said gaseous discharge devices, one side of the second.

filament of said first gaseous discharge device beingconnected to a part of said transformer to have at least the voltage of said first secondarynwinding applied thereto on open circuit, a condenser in series with. said first gaseous discharge device in aloop includingtthe said :first secondary winding, therfirst side of each of the filaments on opposite ends of thetsecond. gaseous discharge device being connected to parts of said transformer other than said junction for applying the voltages of windings including at leastboth secondaries across the same, the discharge devicesbeing ignited in the order named by virtue of a phase reversal in the voltage of said first secondary Winding after ignition of the first gaseous discharge device, a plurality of filament windings closely coupled with the primary winding and connected to .continuously supply current to said filaments through the. terminals of said filaments, andga non-magnetic gap at the end of said central winding leg.

4. Apparatus as claimed in claim 3 in which there is a second gap at the other end of said central winding leg.

5. Apparatus as. claimed in claim 4 in which the second secondary winding is connected. between the primary and first secondary windings,.and thesaid. first gaseous discharge device and said condenser are connected inseries together across: said first secondary winding, and the second gaseous discharge device is connected across primary and both secondary windings together.

6. Apparatus as claimed in claim 4 in which the first secondary winding is connected between the primary and second secondary windings, and the said first gaseous discharge device and said condenser are connected in series together across the primary and first secondary windings, and the second gaseous discharge device is connected across both secondary windings.

References Cited in the file of this patent UNITED STATESPATENTS 2,504,549 Lemmers .Apr.. 18, 1950 2,510,209 Bridges June 6, 1950 2,585,963 Ranney Feb. 19, 1952 2,611,885 Bridges Sept. 23, 1952 2,683,240 Strange July 6, 1954

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