US2514863A - Multiple circuit breaker - Google Patents

Description

July 11, 1950 G. D. HANCHETT, JR

MULTIPLE CIRCUIT BREAKER Filed Dec. 6, 1947 W 1 Ema Em Sw Q R wsfi m m$5 m mxvwmi 8 EEE 6% 3 T {mum llll lbw? him P a Q 1 1 1 1 1 1 .a Q r R Q W J. DGPMMWDGD v M w l m u m vm mm m mm INVENTOR GEORG D. HANCHETT' uck ATTORNEY Patented July 11, 1950 MULTIPLE CIRCUIT BREAKER George D. Hanchett, Jr., Millburn, N. J assignor to Radio Corporation of America, a corporation of Delaware Application December 6, 1947, Serial No. 790,060

12 Claims.

The present invention relates to circuit breakers and, more particularly, to a circuit arrangement for providing overload protection for a plurality of separate circuits. All of the other heretofore known methods available for protecting radio transmitters and equipment of which I am aware have certain disadvantages. Fuses are not very reliable and for high voltage proection are relatively expensive. Magnetic circuit breakers, while ordinarily superior to fuses, ore quite expensive when a number of circuits have to be protected. Furthermore, a magnetic circuit breaker is not easily reset. Circuit breakers of this type are ordinarily equipped with a local directly acting operating lever for resetting. The circuit breakers are either mounted directly on a radio transmitter panel itself or somewhere on the power supply chassis. Thus, when a breaker operates, it is necessary to leave the operating position and go to the breaker to return the transmitter to the air. In the event it is desired to arrange such circuit breakers for remote resetting, some form of magnetic resetting device is required but this feature greatly increases the cost of the circuit breaker.

An object of the present invention, therefore, is to provide a multiple circuit breaker which will overcome the foregoing difficulties.

Another object of the present invention is the provision of an arrangement for using electronic tubes to accomplish circuit protection.

Another object of the present invention is the provision of an electronic circuit breaker which will protect several independent circuits with the same breaker.

A further object of the present invention is the provision of an electronic circuit breaker which may be reset by throwing a simple switch which may be located at any convenient location.

Sti l another object of the present invention is the provision of a circuit breaker as aforesaid which will immediately reoperate if the circuit fault has not cleared.

Still a further object of the present invention is to provide a circuit breaker which is fast enough in action to prevent damage to meters associated with the circuits protected.

The foregoing objects and others which may appear from the following detailed description are attained by providing an electronic circuit breaker using a number of Thyratrons or gas discharge tubes having a common plate circuit including a circuit opening relay. The gas discharge tubes are so arranged that .space currents of the .various stages in the radio transmitter with which they are associated apply predetermined voltages to the control grids of the tubes. When these values are exceeded, the gas discharge tubes are triggered into action. The resultant plate current flow through the common relay winding opens a circuit supplying plate potential to the transmitter. Due to the nature of a gas discharge tube, once the grid has been triggered, plate current continues to flow until the plate potential is reduced below ionization potential. The control circuit for reclosing the main circuit breaker is so arranged that the operation of closing the main circuit breaker removes plate potential from the gas discharge tubes.

An additional feature of the present invention is the arrangement of small filamentary lamps in the individual plate circuits of the gas discharge tubes adapted to become illuminated when the gas tubes draw current. These small lamps thus act as pilot lights to indicate which of the various stages of the transmitter is causing the trouble.

While the present invention is described as being applied to a radio transmitter, it may equally well be employed for circuit protection when a number of separate circuits are supplied with current from a single source and it may not be undesirable to disable all circuits upon failure of any one individual circuit.

To insure fast action, the initial relay current may be increased by about 50% through the use of a condenser charged by a resistance in series with the source of anode potential for the gas tubes. Upon ionization of the gas discharge tubes, the energy in the condenser is discharged through the relay coil, causing increased speed of operation of the protective relay. After the initial charge has been dissipated, only normal relay current flows.

The present invention will be more fully understood by reference to the following detailed description which is accompanied by a drawing having a single figure. In this figure a radio transmitter T is indicated in block diagram form as including, for example, an oscillator O, a buffer amplifier A, a modulator M and power amplifier PA, each of which is to be separately monitored for excessive anode current. A high voltage supply for the anode circuits of the various stages in transmitter T is supplied by high voltage power supply Ill. The filaments of the various stages are preferably supplied from separate windings of a filament transformer [2. Thus winding l4 supplies filament current to the oscillator stage and windings l6, l8 and 20 supply filament current to the bufier amplifier A, modulator M and power amplifier PA respectively. The primary 22 of the filament transformer is connected to the usual 110 volt, 60 cycle power source through the filament control switch 24. The filament control switch also applies 110 volt, 60-cycleenergy to the primary of a power transformer 30 having a high voltage winding 3|, a rectifier filament winding 32 and a further filament winding 33. The high voltage winding 3! and the filament winding 32 are connected to rectifier tube 35 in a conventional full wave rectifier connection. flhe resultant'direct current output is filtered by a series resistance 36 and a filter condenser 31 having a bleeder resistor 38 thereacross. Thefiltereddirectacmrent is applied, through relay winding ,56 tothe anodes of gas tubes 50, 52 and 54.

Now, the filament windings l6, I8 and 20 sup-- plying the transmitter stages A, -M-and PA each have mid-taps Which-would normallybedirectly connected to round or the negative side of-the high voltage supply-to -com plete the anode current circuit. In some casesbias resistors may be 40, 42 and 44 are connected between thecenter =taps of windings l6, Iii-and 20 respectively and ground. These'resistors are large enough in resistance to produce -avoltage thereacross some- What in excess of two volts-at-the minimum current desired for circuit breaker operation. Po-

tentiometer-s 45 connected across each of the resistors All, 42 and M provide for fineadjustment to the exact voltage-to be appliedto the grids of -tubes 50, 52 and =54-for triggering ofi these tubes when excessive anode currents are drawn by the various-stages of the transmitter. The moving -arm of eachofthepotentiometers tli is connected 'to the control grid of one of the gas discharge pentodes 50,52 and' '4. In-the anode circuits of =each ofthese tubes is connected a :filamentlamp 55 serving as a pilot lightto indicate which gas tube is operating, and :thus the stage of the transmitter which is in trouble. 'The screen electrodes and cathodes of each of the tubes-5l,-'52 and 54 are connected together and to the negative end ofresistor 38. "This terminalis connected to ground through the further resistor 51 ibypassed by condenser'58. "-Resistor 5l acts'as -a cathode 'bias resistor setting the standing bias -on tubes 50, '52 and 54 simultaneously, which must beat 'least overcome by the-positive potentialapplied to their grids from resistors 40, 42 and M. Now, when the voltage dropacross-any of the resistors 40, 42 and 4'4 exceedsthe predetermined negative grid potential applied by resistor'51-the gridof corresponding tube 50,-=52, or 54 becomes=positive to such an extent that the tube becomes conductive. This causesa'fiow'ofcurrent from the rectifier 35 throughthe-windi-mg-ofrelay' 56, causing relay 56 to separate its contacts 60. This opens the circuitbetween-the LlO volt supplyand 'the input terminals or the high voltage power supply It. Thelamp55 associated with-theconductive gastube I also lights.

Inthe circuit between the power source and the input-terminals of ypower supply It] iscon- 'nected -half of a=double pole single throw switch 62. The otherhalf orthe switch is connected in series between the winding of relay 56 and'the anodes of tubes 50, 52 and 54; Now toreenergize the transmitter the operator opens switch 62 which removes the input to the high voltage power supply Ill and simultaneously opens the circuit between the rectifier and the gas discharge tubes 50, 52 and 54. This causes the conductive one of these tubes to cease drawing anode current. Relay 55 drops back and closes its contacts 60. Reclosingthe plate powerz-switch 62 reapplies anode potential to the transmitter T. If the fault in the transmitter which causes the increase of voltage drop across the resistors 80, Mandi-dis still present, the circuit breaker immediately reopens.

The-use-ofa large filter capacitor 3? for the rectifier supply and the gas discharge tubes provides a reservoir of energy which increases athevspeed -'of:,oper ation of relay 56. After the initial charge stored in condenser 3'! has been dissipated, however, only normal relay current flows because it is limited by the resistance of resistor 3B and the pilotlamp55 in the energized gas discharge tube circuit. "It'has been found that the action of the circuitbreaker isfast enough in most cases'so that the pointerof a meter connected in theplate supply of the trans- -mitter will not reach "full scale deflection even on a deadshort circuit.

'Since the electronic'circuit breaker is usually operated near strong radio'frequency fields, it is desirableto incorporate some radio frequencyifilter in the grid circuit of each gasdischarge tube. This isprovided by a mica-capacitor l0 connected directly across tube socket connectionsto the scribed from the viewpoint of protecting :three separate stages in a radio-transmitter, any additional number of circuits which it may beds- -sired to protect, may be protected by merely adding-extra gas discharge tubes in circuits sim- -ilar to thoseshown-for 58,52 and 5t and connected to a resistor in-the circuit to be protected having a voltage drop thereacross which varies in the desired sense. Furthermore, while the foregoing description hasbeen predicated on the=use of the filamentary type tubes utilizing a center tapped filament winding on transformer 12, indirectly heated cathode type tubesmay be used in the transmitter, the protective resistances, 42 and 44 being placedin series between the cathode returns of the various stages and a common ground connection. What is claimed is: :1. A circuit breaker arrangement including a mumberof resistors one individual to each of a number of circuits to'be protected, a gas-discharge tube associated with each of said resistors, said tubeseach having'a controlelectrode and an anode,a connection from the control electrodeof each of said "tubes'to its associated resistor and connections from said anodes through a common winding of arelay to a source of potentialpsaid -relay having normally closed backcontacts connected betweenall of said circuits and another source of potential.

2. A circuit breaker arrangement including a number of resistors, one individualto each of a numberof circuits to be protected, a gas discharge tube associated witheach of said-resistors said tubes each having a control electrode and 'an anode, a connection from the control electrode of each of saidtubes 'to its associated resistor' and connections fromTsaidanodesithrough. a common winding of a relay to a source of potential, said relay having normally closed back contacts connected between all of said circuits and another source of potential, and means for disconnecting and reconnecting said source of anode potential to reset said circuit breaker arrangement.

3. A circuit breaker arrangement including a number of resistors, one individual to each of a number of circuits to be protected, a gas discharge tube associated with each of said resistors, said tubes each having a control electrode and an anode, a connection from the control electrode of each of said tubes to its associated resistor so arranged that as the current through said resistor increases, said control electrode becomes positive, means for applying a standing negative bias to each of said control electrodes and connections from said anodes through a common winding of a relay to a source of potential, an indicator lamp in each of the last-mcntioned connections, said relay having normally closed back contacts connected between all of said circuits and another source of potential.

4. A circuit breaker arrangement including a number of resistors, one individual to each of a number of circuits to be protected, a gas discharge tube associated with each of said resistors, said tubes each having a control electrode and an anode, a connection from the control electrode of each of said tubes to its associated resistor to render said control electrode positive as the current through said resistor increases, means for applying a standing negative bias to each of said control electrodes and connections from said anodes through a common winding of a relay to a source of potential, an indicator lamp in each of the last-mentioned connections, said relay having normally closed back contacts connected between all of said circuits and another source of potential, and means for discon-- necting and reconnecting said source of anode potential to reset said circuit breaker arrangement.

5. In a radio transmitter having a number of separate stages, a connection from a power supply for said transmitter to each of said stages, said connection including normally closed back contacts of a relay, individual resistors connected from each of said stages to ground, a number of gas discharge tubes each having a control electrode and an anode, a connection from each of said control electrodes to one of said resistors, connections from all of said anodes through a winding of said relay to a source of potential, means for biasing said control electrodes to render said tubes inactive for normal current flow through said resistors, said control electrode connections being arranged whereupon an increase in current through any of said resistors above a predetermined value will cause the associated gas tube to ignite, the anode current flowing through said relay winding acting to open said normally closed contacts.

6. In a radio transmitter having a number of separate stages, a connection from a power supply for said transmitter to each of said stages, said connection including normally closed back contacts of a relay, individual resistors connected from each of said stages to ground, a number of gas discharge tubes each having a control electrode and an anode, connections from each of said control electrodes to one of said resistors, connections from all of said anodes through a winding of said relay to a source of potential, means for so biasing said control electrodes to render'said tubes inactive for normal current flow through said resistors, said control electrode connections being arranged whereupon an increase in current through any of said resistors above a predetermined value will cause the associated gas tube to ignite, the anode current flowing through said relay winding acting to open said normally closed contacts, and means for disconnecting and reconnecting said source of anode potential to extinguish said ignited gas tube.

7. In a radio transmitter having a number of separate stages, a connection from a power supply for said transmitter to each of said stages, said connection including normally closed back contacts of a relay, individual resistors connected from each of said stages to ground, a number of gas discharge tubes each having a control electrode and an anode, connections from each of said control electrodes to one of said resistors, connections from all of said anodes through a Winding of said relay to a source of potential, means for biasing said control electrodes to render said tubes inactive for normal current flow through said resistors, said control electrode connections being arranged to ignite any of said tubes upon an increase in current above a predetermined value through the associated resistor, the anode current flowing through said relay winding acting to open said normally closed contacts, and an indicator lamp in each of the connections from said anodes to said relay winding.

8. In a radio transmitter having a number of separate stages, a connection from a power supply for said transmitter to each of said stages, said connection including normally closed back contacts of a relay, individual resistors connected from each of said stages to ground, a number of gas discharge tubes each having a control electrode and an anode, connections from each of said control electrodes to one of said resistors, connections from all of said anodes through a winding of said relay to a source of potential, means to bias said control electrodes to render said tubes inactive for normal current flow through said resistors, said control electrode connections being arranged to render any one of said tubes active upon an increase in current above a predetermined value through the corresponding resistors, the anode current flowing through said relay winding acting to open said normally closed contacts, means for simultaneously disconnecting and reconnecting said power supply and said source of potential to reinactivate said activated tubes and reactivate said transmitter, and an indicator lamp in each of the connections from said anodes to said relay winding.

9. An arrangement for disconnecting a power supply from a plurality of circuits upon the current in any one of said circuits exceeding a value predetermined therefor, said arrangement including a plurality of gaseous discharge tubes each having a cathode, a control electrode and an anode, a source of direct operating potential for said tubes, a relay having a winding connecting said source of direct operating potential across the anode-cathode path of all of said tubes and a normally closed contact structure, contacts of said structure being interposed between said power supply and all of said circuits, a resistive element in each of said circuits responsive to said current flow therein, and means to connect the resistive element in each of said circuits to the control electrode of a corresponding tube to render the same conductive upon the current flowing in said resistor exceeding a predetermined value therefortoactuate said relay and open. said contacts to disconnect said power supply ,from .Said circuits.

10. An arrangement for disconnecting a power supply from a plurality of circuits upon the current in any one of saidcircuits exceeding a value predetermined therefor, said arrangement including a plurality of gaseous discharge tubes each having a cathode, a control electrode and an anode, a source of direct operating potential for said tubes, a relay having a winding connecting said source of direct operating potential across the anode-cathode path of all of said tubes and a normally closed contact structure,.contacts. of said; structure being interposed between said power supply andall of said circuits, a resistive element in each of said circuits responsive-tosaid current flow therein, means to connectthe resistive element in each of saidcircuits to thecontrol electrode of a corresponding tube to render the same conductive upon the current flowing in said resistor exceeding a predetermined valuetherefor to actuate said relay and open said contacts to disconnect said power supply from said circuits,

and means connected to said relay windin to I provide aninitial surge of relatively, high current therethrough to increase the speed of operation of said relay.

11. Anarrangement, for disconnectinga power supply from a plurality of circuits upon thecurrent in any one of said circuits exceeding a value predetermined therefor, said arrangement includin a plurality of gaseous discharge tubes each-havinga cathode, a control electrode and an anode, a source, of direct operating potentialflfor said tubes, a relay having a winding connectin said source of direct operating potential across the anode-cathode path. of all of said tubes and a normally closed contaetstructure, contacts of said structure being interposed between said power supply and all of said circuits, a resistor in each of saidv circuits responsive to said ourrent flow therein, means to connect the'resistor in each of said circuits to the control electrode of a corresponding tube to render the same conductive upon the current flowing in. saidresistor exceeding a predeterminedvalue therefor to ac- 8 tuatesaidrelay and open said contacts to disconnect said power supply from said circuits, and means interposed in the anode circuit of said tubes to disconnect and reconnect said source of operating potential to render the conductive tube inactive toreset said arrangement.

12. An arrangement for disconnecting a power supply from a plurality of circuits upon the current in any one of said circuits exceeding a value predetermined therefor, said arrangement including a plurality of gaseous discharge tubes each having a cathode, a control electrode and an anode, a source of direct operating potential for said tubes, a relay having a winding connecting said source of direct operating potential across the anode-cathode path of all of said tubes and a normally closed contact structure, contacts. of said structure being interposed between said power supply and all of said circuits, a resistor in each of said circuits responsive to said current flow therein, means to connect the resistor in each of said circuits to the control. electrode of a corresponding tube, means to bias said tubes to render the same conductive only upon the current flowing. in the corresponding resistor exceeding a predetermined value therefor to actuate said relay and open said contacts to disconnect said power supply fromsaid circuits, and a filter circuit comprising a series resistor and a shunt capacitor connected to said relay winding to provide an. initial surge of relatively high current therethrough to increase the speed of operation of said relay and thereafter to limit the current torthe normal value.

GEORGE D. HANCHETT, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,506,275 Stevenson Aug. 26, 1924 1,671,205 Oswald May 29, 1928 1,743,443 Fearing Jan. 14, 1930 2,064,192 Brown Dec. 15, 1936 2,079,446 Goldsmith May 4, 1937

Images