US2301891A

US2301891A - Device for starting and feeding electric discharge tubes under low pressure

Info

Publication number: US2301891A
Application number: US285111A
Authority: US
Inventors: Lecorguillier Jean
Original assignee: Societe Anonyme pour les Applications de lElectricite et des Gaz Rares Etablissement Claude Paz et Silva
Current assignee: Claude Paz et Visseaux SA
Priority date: 1939-03-29
Filing date: 1939-07-18
Publication date: 1942-11-10
Anticipated expiration: 1959-11-10

Description

DEVICE FOR STARTING AND FEEDING ELECTRIC DISCHARGE Nov. 10, 1942. LECORGUILLIER 2,301,891

TUBES UNDER LOW PRESSURE Filed July 18, 1939 Patented Nov. 10, 1942 nsvrcs roa srsnrmo AND rssnmo use. 'rnro mscnsncs 'russs rmnsn LOW reassess Jean Lecorguillier, Suresnes, France, assignor to Societe Anonyme pour les Applications de UNITED STATES PATENT, OFFICE lElectricite a; des Gas Rares-Etablissements Claude-Pal & Silva, Paris, France Application July 18, 1939, Serial N0. 285,111 In switlel'lantl March 29, 1939 Claims. (or. 176-124) There are known so-called constant voltageconstant current circuits which are formed of combinations of tuned inductance and capacitance elements and which, when they are supplied from a constant voltage source at their in systems, hereinafter called feed systemsl'to the operation of low voltage electric discharge tubes.

, These tubes are fitted with therm'o-emitting electrodes heated by the discharge from a constant voltage alternating source, for instance one of the usual low tension sources (110 or 220 volts). Only those voltages are permitted in a receiving circuit which do not exceed the limit authorized by the regulations for usual distributions. Furthermore, the device according to the invention, which does not work with a uniform intensity, occupies a minimum of space, consumes very little energy, and has ahigh power factor, without reducing the life of the tube employed.

The accompanying drawing shows merely by way of example an embodiment of the invention, comprising a constant voltage-constant current circuit of the Wheatstone bridge type. 1

In this drawing, A and B designate the terminals of the constant voltage source of distribution. C and liartlieterminals of the receiving circuit. and 3 are the inductorsfand 2 and l are thecapacitors of the feed system, these elements being respectivelitequal to each other., I

' 'isthe stabilizing inductanfioeilln s ries with the luminescent discharge 0 The fuse'is-findl catedat I.

According to the present invention, when th tube is connectedin series with an inductance *coil in the receiving circuit, the following conditions are simultaneously complied with:

(a) The stabilizing impedance has such a value that it would secure the stability of the tube when the tube with its impedance is supplied with aconstant voltage, this voltage actually being lower than twice the voltage across the tube under working conditions:

three times the constant input voltage and at most equal to the maximum voltage permitted by the regulations concerning low voltagev systems (for instance 250 volts in France);

(0) The circuit leading .to the terminals of the source of distribution includes a device for automatically cutting oii the current (fuse or circuit-breaking relay) adjusted to operate at the open circuit current.

The stabilizing impedance such as deilned above prevents any rapi d deterioration of the electrodes during the starting oi the tube and its operation. Its value is very much higher than it would be advantageous to use with a tube having cold electrodes. It isimportant to note that thevalueoiithisim pedance is indepeuilent of the supply circuit and of thevalue of the elements thereof, although these elements intervene for the stabiligation of the tube.

Stabilization with the constant voltage supply considered at a. above is to be considered as secured when a change of current in the tube be tween and 18% corresponds to an incidental change of 16% in the normal supply voltage. In

the present invention, owing to the influence oi the feed system elements, the stabilization obtained for the'entire device will of course be still better.

ated by the provision oi a current cutting means,

which allows these elements tobe dimensioned only-as far as necessary for the flow of a curthe tube starting voltage, but it is lower refit. equal to that which passes therethrough whenthetube is being started, during the period for bringing itinto normal oger ating qondifl It has been founit tQatthe starting tim,"desplte' the low'overvoltage employed for this starting, is

sumciently short to .allow a material reduction inthe sizeof the system. 'IhesLeis very small compared with that which would behecessu'y in the absence of the circuit-breaking meansfif the elements had been chosen in such manner as to support the current flowing therethrough in case the was brought out of service.

The automatic circuit breaking means may be a delayed action fuse, adjusted to operate after the elapsing of the time required for starting the tube, provided the tube has not actuallybeen started. This fuse comprises for instance an electric heating coil, which may be made of a metal the resistance of which increases considerably when the temperature rises, surrounding a mass of fusible alloy, for instance-Lipowitz alloy (26.3% of lead, 13.3% of tin, 50% of bismuth, of cadmium, melting point 70 C.) with which it is in series. The fuse may be terminated by a spring under tension with one of its ends embedded in the fusible mass. But it has been found that in most cases it is sufficient to employ an automatic current circuit breaking means acting without delay, for instance an ordinary fuse. The same is true when the interval between the open circuit current and the starting current is rendered sumcient to permit the starting of the tube without operating the circuit breaking means. The starting input current can be reduced with respect to the open circuit current in a suitably proportioned plant (as to the voltage delivered by the supply network, the starting voltage and the characteristics of the tube). larger than the starting current as the following two ratios are larger, firstthe ratio of the starting voltage to the working voltage at the output, and second-the ratio of the open circuit current a to the working current at the input. The inductance coil iif'seri'es with the tubeis preferably proportioned so that the induction therein developed by the starting current is sufiiciently low to avoid saturation by the temporary current peaks, such as occur duringtlre, starting. This induction is chosen, for instance, togrange from 66% to i590 Gauss. v

What I claim is:

l. A circuit arrangement for supplying an electric discharge lamp with current from a low voltage source comprising, a ballast impedance in M series with said lamp, the value of said impedance The open circuit current is in fact inn the current in being such that an incidental change,oi-l0%"in the voltage applied rto thrrlamfland its impedance will cause a change of less than 30% in the current' in the lamp when said voltage is lower than approximately twice the voltage across the lat open circuit current of the net lamp under working conditions, a network of the constant voltage-constant current type including two sets of inductances and capacitances, each of said sets comprising one-inductance and one capacitance connected across said discharge tube and its impedance, the inductances and capacitances being respectively equal to each other, said network having its input and output sides connected to said low voltage source and said circuit respectively and being so proportioned as to yield at its output side an open circuit voltage lower than a predetermined value below approximately three times the constant input voltage and a working output as required by said circuit, a circuit breaker in the input connections of said network which will withstand and maintain the circuit closed during the,starting of the tube but which will break the circuit M work; the elements ofthe circuit being of smaller size than that which would be required under a steady open circuit operation of the network.

, 2. A circuit'arrafigement for supplying an electric disch arge'lamp with current from a low voltage source comprising, a ballast inductance in series with the lamp, said ballast inductance being so proportioned as not to be saturated by the current peaks occurringsin the network during the starting of the lamp and having such a value that an incidental change of 10% in the voltage applied to the lamp and its impedance will cause a change of less than 30%. in the current in the lamp when said voltage is approximately lower than twice the voltage across the lamp under working conditions, a network of the constant voltage-constant current type including two sets of inductances and'capacitances, each of said sets comprising one inductance and one capacitance connected across said discharge tube and its impedance, the inductances and capacitances being respectively equal to each other, said network having its input and output sides connected to said low voltage sourceand said circuit respectively and being so proportioned as to yield at its output side an open circuit voltage lower than a predetermined value below approximately three times the constant input voltage and a-working output as required by said circuit, a circuit breakerin the input connections of said network which will withstand the input current and maintain the circuit closed during the starting of the tube but which will break the circuit at open circuit current of the network; the elements of the circuit being of smaller size than that which would be required under a steady open circuit operation of the network. v 3. A circuit arrangement for supplying an electric discharge lamp with current from a low voltage source comprising, a ballast impedance in series with said lamp, the value of said impedance being such that an incidental change of 10% in the voltage applied to the lamp and its impedance willcauseachangeof less than 30% approximately lower than twice the voltage across the lamp under working conditions, a network of the constant voltage-constant current type including two sets of inductafices and capacitances, each of said sets comprising one inductance and one capacitance connected across said discharge tube and its impedance, the inductances and capacitances being respectively equal to each other, said network having its input and output sides connected-to said low voltage source and said circuit respectively and being so proportioned as to yield at its output side an open circuit voltage lower than a predetermined value below approximately three times the constant input voltage and a working output as required by said circuit, a circuit breaker of the delayed action type in the input connections of said network which will delay over the time required for starting the tube and maintain the circuit closed but will break the circuit at the network; the elements of the circuit being of smaller size than that which would be required under a steady open circuit operation of the the input; w-age source comprising, a ballast impedance in series with said lamp, the value of said impedance being such that an incidental change of 10% in the voltage applied to the lamp and its impedance will cause a change of less than 30% in the current in the lamp when said voltage is approximately lower than twice the voltage across the lamp under working conditions, a network of the constant voltage-constant-current type including two sets of inductances'and capacitances, each of said sets comprising one inductance and one catthe lamp whenlsaid voltage is open .circuitcurre of pacitance connected across said discharge tube and its impedance, the inductances and capacitances being respectively equal to each other, said network having its input and output sides connected to said low voltage source and said circult respectively and being so proportioned as to yield at its output side an open circuit voltage lower than a predetermined value. below approximately three times the constant input voltage and a working output as required by said circuit, and which,-during the starting of the lamp, will take an input current substantially lower than the open circuit input current, a circuit breaker in the input connections of said network which will withstand the input current and maintain the circuit closed during the starting of the tube but which will break the circuit at open circuit current of the network; the elements of the circuit being of smaller size than that which would be required under a steady open circuit operation of the network.

5. A circuit arrangement for supplying an electric discharge lamp with current from a low voltage source comprising a ballast impedance in series with said lamp, the value of said impedance being such that an incidentalchange of 10% in the voltage applied to the lamp and its impedance will cause a change of less than 30% in the current in the lamp when said voltage is approximately lower than twice the voltage across the lamp underworking'conditions, a network of the constant voltage-constant current type including two sets of inductances and capacitances, each of said sets comprising one inductance and one capacitance connected across said discharge tube and its impedance, the inductances and capacitances being respectively equal to each other, said network having its input connected to said low voltage source and its output connected to the lamp and its impedance and being so proportioned as to yield at its output side an open. circuit voltage lower than a I predetermined value below-approximately three times the constant input voltage and yielding a working voltage as required by said lamp, an automatic circuit breakerof the delayed action type in the input connections of said network, said circuit breaker being adjusted to operateupon failure of the lamp to start; after atime interval normally required to start the lamp, the elements of the circuit being of-smaller size than that which would be required under a steady open circuit operation of the network.