US2341520A - Starting and operating circuit for gaseous electric discharge devices - Google Patents

Description

1944. M. A. BABE 2,3415% STARTING AND OPERATING CIRCUIT FOR GASEOUS ELECTRIC DISCHARGE DEVICES Filed Feb. 20, 1941 moammomnmn 40- h E I l 4/ 50 ATTORNEYS Patented Feb. 1944 2,341,520 I STARTING AND OPERATING CIRCUIT FOR GASEOUS ELECTRIC DISCHARGE VICES Maynard A. Babb, Tenafly, N. J. Application February 20, 1941, Serial No. 379,756 19 Claims. (Cl. 315-100) The present invention relates primarily to hot electrode vapor or gaseous electric discharge devices commonly embodied in hot cathode gaseous lamps and while it has an important application to fluorescent lamps of that type, it is not limited to such devices.

As conducive to a clear understanding of the invention, it is noted that when a lamp of the above type becomes defective, as for instance due to wearing or chipping ofl of the emissive filament coating or for other reasons, the arc strikes with difllculty and does not maintain itself, so that the lamp flashes on and off intermittently at short irregular intervals, as long as the lamp is in circuit, resulting in annoyance to all persons in the vicinity of the defective lamp, in waste of power and in rapid destruction of the starting interrupter.

While the magnetic type of starting interrupter has important advantages, among other reasons, because of its rapid cycle and the consequent effectiveness of ballast kick which facilitates starting, the rapid destruction noted, due to pitting of its contacts in the prolonged rapid make and break thereof with a defective lamphas militated against its wider use.

Though they impart a less effective ballast kick, the thermal and the glow switch type of l starting interrupters have been extensively used, since their relatively slow operating cycle leads to long life thereof, provided however that the switches, which in many instances have a life no greater than that of the lamp.

It is among the objects of'the invention automatically to protect any of the familiar types of starting interrupter (regardless whether the same be of the magnetic, the thermal, the glow switch or other type, when used in any of the conventional circuits), from further operation thereof, if the lamp should be so defective as not to maintain its are at the end of the brief interval adequate in normal starting operation.

Another object is to provide simple means whereby the starting impulses upon the lamp are and remain inhibited, except for a brief interval 'of intermittent flashes upon each closure of the main switch which apprises of the need for replacement, and in which the act of removal of the defective lamp results automatically in restoring the lamp starting device to operativeness.

Essentially the invention involves the use of a self-closing time delay switch, opened due to the prolonged starting current in the attempted starting of a defective lamp, to interrupt the starting connection between the electrodes and to complete a normally open by-pass circuit that has circuit characteristics such as to pass suflicient current to prevent the time delay switch from reclosing, thereby to inhibit starting impulse upon the lamp. The time delay switch is desirably of the temperature controlled, preferably of the bi-metallic snap switch type, which rspondsto the heat generated by undue prolongation of the starting current.

In the accompanying drawing in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. 1 is 'a diagrammatic view of one circuit incorporating the invention,

Fig. 2 is a view similar to Fig. 1 showing one application of the invention to a lamp of higher voltage,

Fig. 3 is a view similar to Fig. 2, showing an embodiment of the invention applied to power factor and stroboscopicaliy corrected two lamp circuits, and

Fig. 4 is a view similar to Fig. 3 showing a desirable application to low-voltage lamps.

Referring now to Fig. 1 of the drawing, the conventional lamp L is shown with electrodes, illustratively filaments e' and e at opposite ends thereof, each coated with electron emissive material such as barium oxide, according to conventional practice.

The starting interrupter is in the starting circuit III, which connects electrodes e' and e in series. Said interrupter which may be of any of the conventional types, such as the magnetic, the thermal or the glow switch type, is shown diagrammatically at I in the open position to interrupt the starting circuit as long as the lamp is arcing and it has the usual condenser 9 thereacross. The circuit includes an iron core ballast coil l2 in main i3 which aids in starting, by imparting an inductive kick each time the starting interrupter opens. The lowering of the power factor of the system due to said ballast coil is compensated for by condenser l5 across the mains II and Il, all in accordance with conventional practice..- Upon closing of the main switch II the electrodes e and e are heated due to the flow of current in series therethrough by way of the starting circuit it which includes the closed interrupter I. As the interrupter opens under the impulse imparted by the magnetic, thermal, glow or other operating instrumentality, in response to the starting current, the break down of flux in col] l2 assists striking of the arc. If the lamp fails to flre the interrupter will reclose and the cycle will be repeated until the lamp has fired,

whereupon the interrupter I will remain open due to the action of the magnetic, thermal or glow device, in manner well understood.

According to the invention, there is included in the series connection l between the electrodes a self-closing time delay switch, preferably a thermally operated switch I8, desirably of the bi-metallic type, closed at contact IT. The switch l8 may be operated from an electric heater It in the series connection ill or may be of the type in which the current is passed directly through the bimetallic element, In the case of an operative or perfect lamp the switch It remains in engagement with its contact I! and the circuit operates in the conventional manner. In the case of a defective lamp, however, the current passing through the starting connection ill in the attempted starting operation is continued unduly because of the failure of the lamp to are, and so generates sufflcient heat in the heater It to deflect the switch it away from contact l1, thereby to open the starting connection.

With the use of the equipment thus far described, th objectionable flashing of a defective lamp would not be inhibited. because upon cooling after interruption of the starting circuit, switch It would reclose and the objectionable flashing would resume and that action would continue as long as the main switch I i remains closed. To prevent such resumption of flashing, mean is provided to pass enough current to the heater I8 of switch It in its deflected position. to prevent recicsure thereof as long as the defective lamp remains in circuit with the main switch ll closed. In Fig. 1, a by-pass lead 20 connected to main H has a contact II to be engaged by the deflected bi-metallic switch 46. The normally open by-pass circuit. when thus closed, extends from main it to ballast coil l2 to electrode e. heater i8, switch 5,. contact 2| and by-pass lead 20 to the other main I. The by-Dass circuit has characteristics such that it passes only sufflcient current therethrough to maintain the temperature responsive switch It in deflected position. To this end, while the by-pass circuit may include a suitable resistance, it-is preferred to use an inductance 22 to impart to said circuit an impedance such, as desirably to pass a current, say of .3 amperes, which is less than that necessary to deflect the bi-metallic switch, but suiflcient to maintain it in deflected position. Desirably, the bi-metallic switch I0 is of the familiar snap switch construction to assure prompt shift from contact I! to contact 2| and to preclude ,inoperativeness due to a floating of the switch arm between the contacts.

Thus with a defective lamp, after intermittent flashing for say six or seven seconds, sufficient heat will have been evolved in the heater I! to cause the deflection of switch It; The starting impulse on the lamp is now inhibited, since the current through the by-pass circuit, maintains the heater ll active to prevent return of the deflected switch It, which maintains the by-pass circuit closed or completed by its engagement with contact II. the destruction of the starter contacts which would be incurred by the intermittently repeated make and break thereof which would occur in the conventional circuit when the lamp becomes defective. Particularly in the case of circuits inlamp on and oil for a few seconds after starting apprises the user of the need for replacement. But the annoyance is obviated of repeated flashing for many minutes or hours, which otherwise is experienced whena relatively inaccessible lamp becomes defective. Opening of the main switch I l or removal of the defective lamp, even though the main switch remains closed, results in interruption of the circuit to heater l8 so that the switch it automatically returns to engage contact I1, and a replacement lamp will start without the need for any manipulation to restore the starting circuit to operativeness. 1

In the embodiment of Fig. 2 is shown the application of the invention to a lamp which requires a higher voltage. Illustratively the supply main 25 and 26 for this purpose are connected across the low voltage terminals of an auto transformer 21, the high voltage terminals of which are connected respectively to electrode e and electrode e of th lamp L. The starting interrupter, illustratively of the magnetic type, is operated by an electromagnetic coil which may be coil 28 interposed between auto transformer 21 and electrode e. Condenser 29 bridges across the interrupter contacts according to familiar practice.

The by-pass circuit lead is devoid of the coil 22 used in the embodiment of Fig.1. Lead 30 is connected to a tap ll close to the grounded side of the auto transformer 21. The remaining elements are identical with those of Fig. 1 and corresponding D rts bear the same reference numerals with exponents 2.

In operation, when due to a defect in the lamp the thermally responsive heater I6 is excessively heated, switch I is deflected to enga e contact 2| and to close the normally open by-pass circuit. The electromotive force applied to the bypass circuit by the auto transformer section 32 between main 25 and tap 3| now causes flow of current through the by-pass circuit. Ordinarily, only sumcient turns of the auto transformer are in the by-pass circuit to impose for example I! may comprise an iron core transformer havingfa" primary coil 40 across the mains and I2 and two secondary coils l3 and II extending in opposite directions, the latter having a condenser Accordingly, there is avoided compensated lamp pair of low voltage.

45 in series therewith, and being closer to the primary than is coil 43, for different leakage inductance thereof.

The two fluorescent lamps are shown at L' and U and are connected across the respectivesecondary coils 43 and 44 of the ballast unit B. The reference numerals are applied to only one of the lamps, the other being identical therewith,

and with the lamps shown in the other embodi- The starting circuit extends from main 42 to I the secondary coil it, the coil 44 in lead 45 to electrode e, the starting switch I under control of coil M, thence to the bi-metallic heater switch it with its heater coil I8 said switch normally engaging contact H to close the series circuit through electrode e to the opposite main 4!. An otherwise conventional two lamp high power factor ballast unit B has a tap 48 close to the grounded end of the primary coil 40, which is connected by lead 4i to the connection 48 be tween, the normally inactive contacts 2i of the by-pass circuits for the respective lamps.

The operation which will be clear from the foregoing description, will now be briefly summarized. In the normal operation of the lamps the condenser 45 in combination with the flxed leakage inductance of secondary coil 44 will effect a phase difference in the operation of the two lamps sufficient substantially to eliminate the stroboscopic effect and greatly to improve the power factor in manner well known to those killed in the art.

If either of the lamps should become defective, then according to the operation previously described, the time delay switch I8 of such defective lamp will be caused to deflect and snap over to interrupt the starting circuit at I I and to close the by-pass circuit at contact 2". The switch I is kept in its deflected position by the current continuously passing through the now closed by-pass circuit, which derives its electromotive force from the section 50 of the primary between main 4i and tap l6 and that circuit is closed from main 4| through electrode e, heater coil ll! of switch I8 contact H and connectors 48 and 41 to tap 46. Thus, a single source of electromotive force, i. e., the section 50 of the two lamp high power factor ballast will prevent reclosure of either bi-metallic switch Iii once such switch has opened due to defectiveness of the corresponding lamp. The inhibition of further flashing of a defective lamp thus occurs without interfering with the continued operation of the companion lamp as long as the same remains operative. In the embodiment of Fig. 4 is shown an application of the self-closing time delay by-pass switch to a power factor and strobosccpically The two lamp high power factor ballast unit B is substantially conventional and illustratively comprises two ballast coils 60 and GI connected in main 82, respectively to electrode e of lamp L and the corresponding electrode of lamp L Ballast Si is of leakage inductance'differing from that of ballast 60 and has a conventional condenser 63 in series therewith which may have a resistance 64 across the terminals thereof.

Where, as illustratively shown, a starting inter-' rupter G of the glow switch type with the usual condenser thereacross is used on each lamp, the

till

conventional compensator C may be connected in series with one of the glow switches G, shown as that for lamp L. That compensator serves to adjust the starting current and to prevent the lamp L" from taking a current diiferent from that supplied to the companion lamp L. The compensator may comprise the usual inductance I! with condenser l6 thereabout if desired., and is also a part of the conventional unit B. Where instead of the glow switch, a magnetic, thermal or other starting interrupter is employed, the compensator 0 might be omitted from unit B.

According to the present embodiment. a reactance. desirably an inductive element 41 shown as an auto transformer is connected across the mains to take the full voltage and a tap 88 therefrom near the grounded side 49 thereof, is connected in parallel to the two contacts 2 l of the bypass or hold-out circuits. Maniiestly the inductive element 61 could also be and preferably would .be built into the unit B. The operation is clear typ it will be understood that in each of the embodiments any of the known types of switches.

includingthe magnetic, the thermal and the glow switch, could be employed.

As many changes could be made in the above methods and circuits and many apparently wide ly different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I. claim as new and desire to secure by Letters Patent is:

1. In hot electrode vapor lamp operation, the method of automaticaly excluding from an operating circuit a defective lamp which otherwise would flash on and off intermittently throughout operation, which method'consists in uti izing the prolonged starting current evolved in the intermittent starting of such lamp upon each closure of the operating circuit to effect opening of the lamp starting circuit and closing of a by-pass and feeding sufllcient current through the bypass to prevent reclosure of the lamp starting circuit as long as the operating circuit remains closed and to cause suchyeclosure to occur when the operating circuit is opened.

2. In hot electrode vapor lamp operation, the method of automatically excluding from an operating circuit a defective lamp which otherwise would flash on and oil intermittently throughout operation, which method consists in utilizing the prolonged starting current evolved in the intermittent starting of such lamp upon each closure of the operating circuit to exert displacement by thermal expansion to effect snap opening of the lamp starting circuit. and thereupon passing sufflcient current to evolve the heat required to maintain said thermal expansion, thereby to prevent reclosure of said lamp starting circuit as long as the operating circuit remains closed and to cause such reclosure to occur when the operating circuit is opened.

3. In a safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes, 9. connection for feeding alternating current through said electrodes in sponse to the prolonged starting current in the attempted operation of a defective lamp, and means to maintain said time delay switch in said operated position as long as the control switch is closed and to release the time delay a switch in response to the opening of the control switch. 3

4. The arrangement defined in claim 3 in which the time delay switch responds to temperature changes and the means last recited in claim 3 comprises an impedance in the safety circuit, permitting the passage of enough current therethrough to maintain a temperature suiiiciently high to keep said switch in operated position 5. In a safety starting and operating circuit for vapor electric discharge devices equipped with spaced electrodes, means effective to establish a series connection through said electrodes, means to interrupt and maintain interrupted said con nection when the arc of the lamp is struck and as long as it is maintained, a normally open bypass line connected with a difference of potential between its terminals, a temperature responsive switch subjected to the heat evolved in the starting circuit due to starting current and arranged to interrupt said series connection under the excess heat generated in the attempted starting of a defective lamp and to close circuit through said by-pass line, said by-pass line having circuit characteristics such as to pass sufiiclent current to keep the temperature responsive switch in deflected position.

6. In a safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes, a series connection between said electrodes, means to interrupt and maintain said series connection interrupted while the lamp is arci g. a bi-metallic switch having a heater normally in said series circuitand arranged to be deflected and to eflect opening of the latter under the excessive heat generated by the prolongd starting current passed in the attempted starting of a defective lamp and a bypass circuit having a gap therein bridged by said bi-metallic switch when deflected, thereby to close circuit therethrough, said by-pass circult having characteristics to assure continuance ofcurrent through said heater suflicient to maintain the bi-metallic switch in deflected position.

7. In a safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes, a starting interrupter, a series connection between said electrodes under control of said interrupter to feed current' when the latter is deflected, s'aid by-pass circuit including said heater therein and having characteristics such as to pass suiiicient current to maintain the iii-metallic switch in deflected posi on.

8. A safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes, comprising a ballast coil connected to one of the electrodes, a series connection between said electrodes, a starting interrupter in said connection, said series connection including a bi-metahic switch closed in normal operation and deflected under the prolonged starting current and the resultant heat evolved in the attempted starting of a defective lamp, a normally open by-pass lead having terminals at different potentials, said bi-metallic switch when thus deflected closing the by-pass circuit,

' said latter circuit having characteristics such that the current through the bi-metallic switch is sufllcient to maintain the same in said de- 1 to maintain said connection interrupted while through said electrodes in series, means for autothe lamp is functioning, a self-closing time delay switch in said series connection deflected by current conditions under abnormal starting operation to open the starting circuit and a normally open by-pass'circuit closed by said switch when deflected, said by-pass circuit having an element therein to impart to it the characteristics required to maintain sufiicient current therethrough for preventing the switch from reclosing and retaining it in deflected position.

- 10. A safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes comprising a series connection between said electrodes having a starting interrupter therein to open and be maintained open during normal functioning of the device, a selfcloslng time delay switch in said series connection adapted to open by the prolonged current passed in abnormal starting operation and a normally open by-pass circuit adapted to be closed by said switch when in deflected position, said by-pass circuit having an inductance therein of value to impart the required characteristics for passing therethrough sufliclent current to maintain said switch in deflected position.

11. In a starting and operating circuit for gaseous electric discharge devices of the high voltage type equipped with spaced electrodes, an auto transformer having a primary coil across the current leads, the high voltage secondary coil being connected across the discharge device, a series connection between the electrodes, a starting ginterrupter therein maintained open while the arc exists across the electrodes, and means for automatically maintaining said interrupter out of operation in the case of a defective lamp, said means comprising a bi-metallic switch in said series connection, a normally open by-pass circuit leading from oneterminal to a part of the circuit at a different potential, said bi-metallic switch being deflected under the heat generated by the prolonged starting current in the attempted starting of a defective. lamp to open said series connection and close said by-pass circuit, said by-pass having circuit characteristics such that suiilcient current is passed therethrough to maintain said bi-metalli switch in deflected position.

- 12. A safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes, comprising a ballast coil in one of the circuit leads connected to one of the electrodes, a bi-metallic switch closed in normal operation, deflecting means for said switch operative under current conditions in starting a defective lamp, a'normally open by-pass circuit closed by said bi-metallic switch when thus deflected, said by-pass circuit being connected for application thereacross of a fraction of the line voltage, to pass through the switch deflecting means sufficient current to maintain the bi-metallic switch in deflected position.

13. In a safety starting and operating circuit for gaseous electric discharge lamps equipped with spaced electrodes, a reactive device in circuit with said lamp for applying operating voltage therelatter is deflected by heat applied thereto under abnormal starting operation, said by-pass circuit having terminals connected across a number of turns of said auto transformer for impression thereon of voltage suflicient to maintain said switch in deflected position.

16. In a safety starting and operating circuit, a pair of mains, a reactive unit having a pair of terminals connected to said mains, a plurality of gaseous electric discharge devices, each equipped with spaced electrodes, each of said lamps having an associated starting circuit connecting the electrodes thereof-in series, each of said series connections having an element therein to be maintained open during normal functioning of the device, and also having a switch adapted to open under the current conditions in abnormal starting operation, a normally open by-pass circuit to, a starting circuit for passing current through said electrodes in series during the starting oper-- ation, means for interrupting said circuit as long as the arc is established across the lamp, a selfclosing time delay switch in the starting circuit and responding to the prolonged starting current in attempted starting of a defective lamp, a normally open by-pass circuit closed by said switch when the latter is deflected due to a defective lamp, said by-pass circuit being connected across a portion of said reactive device.

14. In a safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes, an auto transformer having a stepped up secondary coil applied across the discharge device, means connecting said electrodes in series during the starting operation, said means having a starting interrupter therein maintained open while the device is arcing, said means also having a self-closing time delay snap switch therein opened in response to the current passed in abnormal starting operation, and a normally open by-pass circuit having terminals con-- nected across a small segment of said auto transformer, said circuit being completed by the opening of said switch and maintained completed by current through the by-pass circuit under the impressed voltage from said auto transformer, thereby to prevent reclosure of said switch.

15. In a starting and operating circuit for gaseous electric discharge devices of the high voltage adapted to be completed. by said switch when in open position, the by-pass circuits of the several lamps having a common source of electromotive force, said common source comprising a short section of said reactive unit.

1'7. The combination recited in claim 16 in which the reactance is an inductance across which the several lamps are connected, the several by-pass circuits being connected across a short section ofsaid inductance at the grounded end thereof. e V

' 18. In a power factor and stroboscopically corrected vapor electric discharge lamp system of the type comprising a two lamp high-power factor ballast, a pair of gaseous electric discharge lamps connected with said ballast, each having spaced electrodes and each having a series starting connection between said electrodes; the combination of means for automatically removing from circuit either ofthe lamps when the same i is defective. said means comprising a self-closing time delay switch in the starting connection, a normally open by-pass circuit closed by the opening movement of the switch, the by-pass circuits of the two lamps being supplied by electromotive force evolved from the ballast.

19. In a power factor and stroboscopically corrected vapor electric discharge lamp system of the low voltage type, a two lamp high power fac- VI tor ballast, a pair of gaseous electric discharge type and equipped with spaced electrodes,. an

auto transformer across the current mains, having a high voltage secondary across the discharge delamps connected with said ballast, each having electrodes and each having a series starting connection between said electrodes the combination of means for automatically removing from said circuit either of the lamps when the same is defective, said means comprising a self-closing time delay switch in the starting connection, a normally open by-pass circuit closed by the opening movement of the switch, a reactance connected across the mains, the by-pass circuits of the two lamps being supplied by electromotive force across a small part of the reactance.

MAYNARD A. BABB.

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