US2026407A - Lighting system - Google Patents

Description

I w. F. WESTENDORP 2,026,407

LIGHTING SYSTEM Filed Nov. 18, 1955 Inventor: willemFwestendorp,

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Patented Dec. 31, 1935 UNITED STATES aosaov LIGHTING SYSTEM 'Willem F. Westenclorp, signor to General Ele ration of New York Schenectady, N. Y., asctric Company, a corpo- Application November 18, 1933, Serial No. 698,618-

8' Claims.

, My invention relates to lighting systems and more particularly to lighting systems in which electric discharge lamps are used.

One object of my invention is to provide'an improved method of operation of the lamps.

Another object of my invention is to provide an improved system for connecting the lamps in series with each other, in which the heating current for the cathodes of the lamps and the operating anode current are transmitted over the same circuit.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, Fig. 1 illustrates diagrammatically a' lighting system in accordance with'my invention; Figs. 2 and 3 show modifications thereof, and Fig. 4 illustrates the characteristics of the operating current used with the system shown in Fig. 3.

Referring to the drawing in detail, Fig. 1 illustrates diagrammatically a source of power l8 provided with a direct current terminal II and an alternating current terminal l2. A terminal I3 serves as a return for both currents. A primary winding 46 connected to any suitable supply of alternating current energizes a secondary winding 41 which supplies alternating current through conductor I2. A secondary winding 48 connected at its midpoint to conductor I3 and at its ends to the anodes of vacuum tube rectifiers 48 whose cathodes are connected to each other through a resistance 58 supplies direct current through conductor II which is connected to the midpoint of resistance 50. A time delay switch I4 is connected to energize, in succession, the operating coils l6 and ll of switches I8 and I9.

- 'I'he switch I9 is provided with two contacts 2| and 22. When the switch is closed it engages contact 2| and thereby connects a conductor 23 to the direct current terminal When the switch I9 is in the open position, that is, when the coil I1 is deenergized, the switch engages contact 22 and thereby connects conductor 23 to the switch contact 24 of switch |8 through a conductor 25. When the operating coil [6 of switch I8 is energized, the switch closes and thereby connects the alternating current terminal I2 through contact 24, conductor 25, contact 22 and switch I9 to the conductor 23.

A number of discharge lamps 26, each provided 7 with an anode 21 and a'filamentary cathode 28,

are supplied in series relation with current from conductor 23. Associated with each lamp 26 is a relay 30 having a coil 3|, a core 32, a shortcircuited coil mounted on the end of the core and amovable contact arm 34. The short circuited coil mounted on the end of the core may be a coil of low resistance wire having several turns. The simplest possible structure is preferable, however, and in the drawing a plain copper disk 33 is illustrated as being mounted on the end of the core 32. When the coil 3| is energized by alternating current, the flux in the core generates eddy currents in the disk 33 which then acts as a single turn short-circuited coil, and the accompanying flux neutralizes the flux of coil 3| which tends to lift the vcontact arm34. Due to the short-circuited coil 33, therefore, the relay is insensitive to alternating current and therefore when the conductor 23 is connected to the alternating current source through switch l8 the contact arms 34 remain in the open position. In the open position contact arms 34 engage contacts 36 respectively, which are connected respectively through conductor 31 to one end of a filamentary cathode 28. The other end of each cathode is connected through a conductor 38 to the coil 3| of a second relay 30. In this arrangement the cathode'of the last discharge lamp 26 is connected to the common return terminal |3 through a conductor 40. Each of-the lamps 26 is further shunted by conductors 4| and 42 connected respectively to the anode and cathode of the tube 1 and through suitable contacts to opposite sides of a film cutout device 43, which breaks down and permits current to fiow only when the tube fails during operation.

In operation the time delay relay |4 first ener-, gizes, in accordance with its setting, the coil 6 of switch l8. Since at this time the switch I9 is in the open position a circuit is closed by switch I8 from the alternating current terminal |2 through the switch l8, contact 24, conductor 25, contact 22, switch l9 and conductor.23 to the first relay coil 3|. Since, as stated above, this relay is insensitive to alternating current, the 45 contact arm 34 remains unaifected and maintains a circuit through its contact 36 and conductor 31 to the first filamentary cathode 28. The other end of this cathode is connected through a conductor 38 to the second coil 3| through which the current flows to the secondary filamentary cathode 28. Current thereby flows in a similar manner through each of the filamentary cathodes in series and through conductor 40 to the return terminal I3, thereby heating the cathodes. When the cathode surfaces have reached the proper temperature, which is reached after a predetermined period of time during which the heater current is flowing, the time switch l4 energizes the coil H of switch I9. The contact arm of switch I9 is thereby moved, into engagement with contact 2| and connects conductor 23 to the direct current terminal ll of the source l0. With this connection, direct current fiows into coil 3|, causing the contact arm 34 to raise and disengage the contact 36. Due to the preheating of the cathode, however, the discharge path within the tubes 26 has become conductive due to the electron emission from the cathode and current thereby fiows through the tubes, the circuit being from coil 3| through a conductor '45 to the first lamp 28, anode 21, across the discharge path within the lamp, cathode 28, through conductor 38 to the next coil 3| and so on to conductor 40 and to the common return terminal l3.

In this arrangement, therefore, the filamentary cathodes of the discharge lamps are connected in series with each other when alternating current is supplied to the circuit and the lamps or discharge paths thereof are connected in series with each other when direct current is supplied to the circuit. a

In the above system discharge lamps having a filling of sodium vapor therein, together with such gases as neon and argon, are'preferably used. It is desirable to maintain the necessary. electron emission from the cathodes during operation and therefore heat must be supplied to the cathodes. In the above-described arrangement, this heating during operation of the lamp is accomplished by'' the arc discharge within the lamp.

In Fig. 2 I have shown a modification of the cathode 28 in which the'anode current fiows through the filament which is arranged in series relation to the discharge path. In this modification the cathode comprises a conductive metal tube 41 within which a filament 48 is totally enclosed and connected to the tube at one end. With this type of cathode the filament can be connected in series with the discharge path so that the operating or anode current can be used to heat the tube 41. Fig. 2, illustrates anarrangement in which the cathode tube 41 is con- "tion of my invention in which the filamentary cathode 28 is connected to the secondary wind ing 52 of a transformer 53. The midpoint of the winding 52 is connected to one end of the primary winding 54 of the transformer 53. The transformer 53 is provided with an open core for the purpose of preventing-saturation thereof. With this arrangement alternating current is supplied to the primary windings 54, which are connected in series by relays 30, in the same manner as the filaments 28 are connected in series in the system disclosed in Fig. l. The windings 54 are disconnected from each other by the relays 30 as soon as direct current is applied to the circuitand the discharge current flows from the filament 28 to,

the winding 52, then through the connections 55 to one end of winding 54 and through the winding to the next anode. 1

In the arrangement of Fig. 3 a direct current having superposed thereon a ripple current, as diagrammatically illustrated in Fig. 4, for example, is supplied to the system after the alternating current has been flowing through the filament a predetermined time. The discharge paths having been made conductive through preheating, as in the arrangement shown in Fig. 1, 10 in combination with the action of transformer 53, the direct current will fiow through the tubes in series with each other. The anode current will also fiow through the cathode and through the current will thereby Y excite the transformer winding 52 and cause an independent current flow in the secondary winding 52 and cathode 28. In the rectifier circuits, which are normally 20 used, a cycle ripple voltage is generated, which when impressed upon the arrangement shown in Fig. 3 is sufficient to energize the filaments to the proper temperature for maintaining a predetermined electron discharge from its sur- 25 face.

In accordance with the provision of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best em- 30 bodiment thereof; but I desire to have it understood that the apparatus shown is only illustraive, and that the invention may be carried out by other means. I

What I claim as new and desire to secure by 35 Letters Patent of .the United States is:

1. In a series lighting system, the combination of a direct current source and an alternating current source, a plurality of electric discharge lamps, each provided with an incandescent cath- 40 ode and an anode, means for connecting the oathodes of -said lamps in series with each other and to said alternating current source, and means for connecting said devices in series relation to said direct current source and for simultaneously breaking the connections between said cathodes.

2. In a series lighting system, the combination of a direct current source and an alternating current source, a plurality of electric discharge lamps, each provided with a filamentary cathode 60 and an anode connected in series with each other, means for connecting said lamps to said alternating current source and for simultaneously establishing a shunt circuit about each lamp whereby the cathodes only of said lamps are connected in 55 series with each other, and time controlled means for simultaneously connecting said lamps tosaid direct cmrent source and for breaking the shunt circuits about each lamp.

3. In combination, an electric discharge de-BO vice including an envelope containing an ionizable gas provided with a filamentary cathode. and an anode, a circuit between said anode and one end of said cathode and a relay operable only by direct current flowing through said device and ar- 65 an alternating current component for creating a discharge across said electrodes and for heating said cathode.

5. The method of operating an electric discharge device having an anode and a filamentary cathode which consists in applying a rectified current having an alternating current component for operating the discharge tube and for applying said alternating current to the cathode of said tube for the purpose of heating it.

6. In a series lighting system, the combination of a direct current source, and alternating current source, a plurality of electric discharge lamps, each provided with a cathode, an anode and circuit connections between said lamps for connecting them in series relation to each other,

means for connecting said lamps to said alternating current source, means for conducting current from saidsource to said cathodes in series relation and in shunt to the respective discharge paths between said anodes and cathodes, means for connecting said lamps to said direct current source a predetermined time after the first con-' nection is made, and means for conducting the current from said second source across the electrodes within said lamps respectively.

7. In a lighting system, the combination of an electric discharge lamp provided with an anode, a cathode, a heater for said cathode, an envelope containing an ionizable gas for enclosing said electrodes, a circuit normally connecting said 5 anode to one end of said heater and in shunt to said electrodes, means for supplying alternating current to said lamp electrodes'for energizing said heater and means responsive to direct current flowing to said electrodes for breaking said shunt 10 circuit and thereby establishing a discharge for enclosing said electrodes, a circuit normally connecting said cathodes in series with each other, and means, responsive to direct current 20 flowing in said circuit for breaking said circuit and for simultaneously connecting said lamps in series with each other,

' WILLEM F. WESTENDORP. 25

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