US3081449A - Contact annunciator with acknowledgment and master alarm relay - Google Patents

Description

March 12, 1963 R. F. WERNLUND 3,081,449

. CONTACT ANNUNCIATOR WITH ACKNOWLEDGMENT AND MASTER ALARM RELAY Filed Feb. 19. 1959 4 Sheets-Sheet 1 RN H 9% w v u v I N959 @N MN \SQQDW H. L I v km N N% 7 ,3? QM RE A A A W1 A J4 l AMAV NA QR AN A i R 4 Sheets-Sheet 2 R. F. WERNLUND AND MASTER ALARM RELAY CONTACT ANNUNCIATOR WITH ACKNOWLEDGMENT March 12, 1963 Filed Feb. 19. 1959 March 12, 1963 R. F. WERNLUND CONTACT ANNUNCIATOR WITH ACKNOWLEDGMENT AND MASTER ALARM RELAY 4 Sheets-Sheet 3 Filed Feb. 19, 1959 March 12, 1963 R. F. WERNLUND 3,081,449

CONTACT ANNUNCIATOR WITH ACKNOWLEDGMENT AND MASTER ALARM RELAY Filed Feb. 19. 1959 4 Sheets-Sheet 4 VOLTAGE SUPPLY I I I United States Patent Robertshaw-Fulton Controls Company, Richmond, Va., a corporation of Delaware Filed Feb. 19, 1959, Scr. No. 794,408 13 Claims. (Cl. 340213) This invention relates to electronic control systems, and more particularly to electrical circuitry and components for monitoring the condition of a group of variables and indicating the presence of an alarm condition.

In certain industrial processes, it is necessary to monitor a large number of variables. Such monitoring is often accomplished by individual condition responsive units which continuously compare some physical parameter such as temperature or pressure with a preset value and derive therefrom the electrical signal related to the magnitude of any deviation which is discovered. Such prior art scanning systems are usually designed to produce continuously variable voltages.

The present invention contemplates a simple and inexpensive On-Oif system for indicating the presence of alarm conditions anywhere in a given installation. With the present invention, there is provided an alarm device which visibly or audibly indicates the closure or opening of any one of a number of individual alarm contacts provided at remote points in an istallation. In the several embodiments of the invention disclosed herein, alarm conditions are signaled by the opening or closing of a set of condition responsive contacts at points remote from the sampling device. The types of conditions which the invention is capable of monitoring may vary Widely. For instance, with the circuitry and components of the present system, the alarm contacts which initiate an audible or visual alarm indication may be actuated in response to excessive vibration in a turbine-generator or other type prime mover. Or, dangerously high liquid levels or temperatures may be used to initiate the closure of contacts and initiate the observable alarm indication provided in the present invention. The invention lends itself equally well to the function of announcing the occurrence of dangerous velocities or pressures of fluid flow in a conduit. Many other types of alarm condition, such as the over-speeding of a rotary machine may be employed for the purpose of actuating the alarm contacts utilized in generating ob servable alarm indications by means of controlled transient electric voltages in the manner disclosed and claimed herein.

Accordingly, therefore, an object of the present invention is a simple On-Oif scanning system for indicating alarm conditions in an installation.

Another object of the present invention is to render a gaseous discharge tube conductive in response to alarm conditions for initiating an electrical transient condition suitable for actuating audible or visual alarm indicators.

A further object of the present invention is to render nonconductive in response to alarm conditions a normally conductive space discharge device for actuating relay circuitry which actuates an alarm.

These and other objects and advantages of the present invention will become apparent by reference to the accompanying detailed description and drawings, in which like numerals indicate like parts, and in which:

FIG. 1 shows diagrammatically one embodiment of the present invention;

FIG. 2 is similar to FIG. 1 and shows ment of this invention;

FIG. 3 is similar to FIG. 1 and shows still another embodiment of this invention;

FIGS. 4A, 4B and 40 show various wave forms of the another embodi- Patented Mar. 12, 1963 pulse appearing at the grid of the space discharge device used in the various embodiments of this invention; and

FIG. 5 is similar tov FIG. 1 and shows still another embodiment of this invention.

Turning now to the detailed description of the invention, and more particularly'to the system shown in FIG. 1 of the accompanying drawings, the numeral 10 has been used to indicate generally the circuitry and components of one embodiment of the invention. In this circuit, there is provided a voltage supply 12 with a grounded positive terminal, and a negative terminal which is conductively connected to one end of a dropping resistor 14. The dropping resistor 14 effectively prevents any tendency of the associated circuitry to oscillate in the manner of a ring type multivibrator.

The opposite end of dropping resistor 14 is connected to a common bus 16, shown immediately to the right of the voltage supply. In the bank of individual circuits connected to the common bus 16, the uppermost individual circuit is seen to include an alarm lamp 18A of the gaseous type. The alarm lamp 18A may comprise any suitably high hysteresis device such as a neon bulb or the like which has the characteristic of becoming ionized at a given potential and thereafter being maintained conductive by a value of potential lower than that of the ionizing potential. v

The alarm lamp 18A is connected in series with one terminal of a normally open alarm contact 20A. The opposite, terminal of the alarm contact 20A is connected to ground through the resistor 22A. The junction point between the alarm contact'20A and the resistor 22A is connected to one plate of a capacitor 24A. The opposite plate of the capacitor, in turn, is secured to a common bus 26.

The parallel bank of individual circuits connected in FIG. 1 between the common bus conductors 16 and 26 will be seen to comprise a group of series circuits, each substantially identical to the uppermost circuit described immediately above. Thus, alarm lamp 183 is connected from common bus 16 to common bus 26 by normally open alarm contacts 20B and capacitor 24B, with the shunt resistor 22B connected to ground between the alarm contacts and the capacitor. In like manner, alarm lamp 18C, is connected from common bus 16 to common bus 26 by means of the normally open alarm contacts 20C and the capacitor 24C, with the juncture between the alarm contacts and the capacitor connected to ground through resistor 220. It will be appreciated that the several alarm contacts are strategically positioned throughout the installation, at the site of the environments sought to be monitored.

To the right of the elements described immediately above, the numeral 28 has been used to identify a conventional plural element space discharge device, such as a triode or the like. The cathode of the device 28 is connected to ground and the control grid element is connected directly to the common bus 26. It will be noted that the grid element is also connected to ground through a grid resistor 30. a V

The anode element of the discharge device 28 is connected to a voltage supply 32 through a relay operating coil F. The coil F is mounted to control a set of normally open contacts F shown immediately to the upper right thereof. Discharge device 28 is normally conductive during normal or non-alarm conditions and thus the contacts F will ordinarily be closed.

To the right of contacts F the reference numeral 34 has been used to designate a momentary contact push button switch which may be spring biased to a normally open position. This switch is depressed :by the operator to acknowledge alarms which have occurred in the system, and to reset the circuitry to detect further alarm conditions. In practice, depressing the switch 34 permits current to flow from the voltage supply 32 through the relay operating coil G connected thereto. This has the effect of energizing and closing a pair of normally open contacts G Since contacts F are usually closed during non-alarm conditions, it will be evident that coil G is able to maintain itself in energized condition by means of contacts F and G after the push button switch 34 has been restored to open position.

The relay operating coil G also controls a pair of normally closed contacts G The contacts G control the alarm circuitry 36, which in turn acts to energize or deencrgize the alarm horn 38. it will be appreciated that the horn 33 may be replaced by other equally suitable forms of audible or visible alarm indicators and that such substitution would be deemed to fall within the scope of the present invention. The relay circuitry associated with the stage 36 and the horn 38 comprises a fail-safe type of circuitry in that it is the de-energizing of the relay G which has the effect of sounding the alarm horn.

All of the lamps 18A, 18B, and 18C in FIG. 1 are extinguished during normal operation throughout the systerm. The several alarm contacts 20A, 29B, and 20C remain open to indicate the non-existence of dangerous vibration, temperature, pressure, or like conditions. The space discharge device 28 conducts anode current which energizes the relay operating coil 'F. As a result, contacts F are closed and operating coil G is able to draw current through contacts G and F This actuation of the coil G holds the normally closed contactsG in open position and prevents the alarm horn 38 from producing an audible signal.

Upon the occurrence of a dangerous condition anywhere in the installation, a set of alarm contacts (say 20A) is caused to close. As a result of such closure, the associated alarm lamp 18A is ionized and caused to glow. Lamps 18A, 18B, and 180 will normally comprise panel lamps which are positioned on a large panel or console to expedite inspection by supervisory personnel. When the alarm lamp 18A is ionized, a sharp pulse of charging current is'drawn by the capacitor 24A. The

resulting negative voltage drop across grid resistor 30 appears at the grid of the tube 28 and momentarily cuts the tube 01f. Relay operating coil "F sufiEers an immediate loss of excitation, which causes the contacts F to drop open. The relay operating coil G is accordingly deprived of energizing current causing the contacts G to close. As a result of this switching sequence, alarm circuitry 36 is caused to apply power to the alarm horn 33 for the purpose of producing an audible signal.

The alarm horn 38 continues to sound until the system is reset. When conduction through device 28 is restored, contacts F are closed. Actuation of the push button switch 34 energizes relay operating coil G, which closes the contacts G in order to maintain current through coil G and interrupt the flow of horn power to halt the alarm.

Continuing now with the detailed description of the invention, and more particularly with the embodiment shown in FIG. 2, the numeral 40 has been used to designate a voltage supply. The supply 40 has a grounded positive terminal, and a negative terminal connected to one end of a dropping resistor 42. The opposite end of the dropping resistor 42 is connected to a common bus 44. The common bus 44 connects to one end of a resistor element 46A. The opposite end of resistor element 46A is isolated from ground by means of an alarm lamp 48A. A pair of normally closed alarm contacts 50A are connected in parallel across the alarm lamp 48A, and the common point between the resistor 46A and alarm lamp 48A is connected to one plate of a capacitor 52A. The opposite plate of the capacitor 52A is connected directly to a common bus "54.

Directly beneath the individual circuit described immediately above, a group of substantially identical circuits have been illustrated between the common bus 44 and the common bus 54. Thus, resistor element 46B is connected from common bus 44 to common bus 54 by capacitor 523 with the alarm lamp 483 and alarm con tacts 50B connected in shunt to ground. Similarly, resistor 46C is connected from common bus 44 to common bus 54 by way of capacitor 52C, with the alarm lamp 48C and the alarm contacts 500 connected in shunt to ground.

To the right, the numeral 56 has been used to identify a space discharge device which is normally conductive during non-alarm conditions. The cathode of the device 56 is tied to ground, and the control grid electrode is connected directly to the common bus 54. In addition, a grid resistor 58 is connected between ground and the grid electrode of the discharge device. By means of the resistor 58', the charging current drawn by any of the capacitors 52A, 52B, 52C when an alarm lamp is ionized is capable of terminating conduction through the space discharge device.

The anode of the space discharge device 56 is connected to one end of a relay operating coil H. The other end of the coil H is connected to receive operating potential from the voltage supply 6t) via a set of normally open contacts H A momentary contact push button switch 62 is connected in parallel with the contacts H The switch 62 is normally biased to open position by suitable spring means or the like, and is used to acknowledge the existence of an alarm condition and to reset the circuitry.

The operating coil H also controls a set of normally closed contacts H which in turn control an alarm circuitry stage 64. Alarm horn 66 is connected to receive operating power from the stage 64.

In operation, the opening of an alarm contact such as 50A in response to a dangerous condition causes the immediate ionization of a corresponding alarm lamp, such as the lamp 48A. At this instant, the charging current for capacitor 52A drawn through grid resistor 58 causes a negative voltage pulse to appear at the grid of the device 56 and render the device non-conductive.

Prior to this time, the tube has been readied for operation by depressing the push button switch 62. Such actuation of the switch, of course, places B+ potential on the anode of the device which causes current fiow through coil H with resultant closure of normally open contacts H Upon the occurrence of an alarm condition, as earlier explained, the sharp negative pulse across resistor 58 interrupts conduction in the discharge device 56. As a result of this condition, contacts H drop open which effectively removes the B+ potential from the anode of the tube. When coil H loses excitation in this fashion, the contacts H are immediately restored to a normally closed condition which causes the application of power to the alarm horn 66. As the negative voltage pulse disappears from the grid of device 56, conduction cannot be resumed because of the absence of anode potential. The alarm horn 66 thus continues to sound until B+ voltage is restored to the discharge device by the momentary closure of the push button switch 62 by an operator. Once this occurs, the flow of anode current through coil H immediately energizes contacts H in order to latch the circuit in condition for another alarm, and the circuitry is capable of alarming again as soon as the next set of alarm contacts open to indicate a hazardous condition.

Turning now to the detailed description of the form of the invention, illustrated in FIG. 3, the numeral 68 has been used in this figure to identify a voltage supply which has a grounded negative terminal. In this form of the invention, the positive terminal of voltage supply 68 is coupled to a common bus 70. The bus 70 is connected to an alarm lamp 72A which in turn is connected in series with a resistor 74A. A normally open alarm contact 76A isolates one end of the resistor 74A from ground.

The juncture between the resistor 74A and the alarm contact 76A is coupled to a common bus 80, by means of a capacitor 78A. Beneath the circuit thus described, it will be noted that individual alarm lamps 72B and 72C are each connected in series with resistors 74B and 74C, respectively. .Alarm contacts 76B and 760 are used to isolate corresponding ends of the respective resistors from ground. Capacitors 78B and 78C, respectively, are used to couple the ungrounded ends of the alarm contacts 763 and 76C to the common bus 80. To the right of this array, the numeral 82 identifies a space discharge device having a grounded cathode as well as a grounded grid resistor 84. The control grid of device 82 is coupled directly to the common bus 80. Directly above the discharge device 82, the reference characters H and H have been used to indicate a relay operating coil and a set of normally open contacts, respectively.

A momentary contact push button switch 62is connected in parallel with the normally closed contacts H The uppermost common connection between the contacts H and the switch 62 is connected directly to the positive terminal of the voltage supply 68. To theright of the space discharge device, a set of normally closed contacts H is used to control the application of power by an alarm circuitry stage 86 to an alarm horn 90.

The occurrence of an alarm condition has the eflect of closing a set of normally open contacts such as the alarm contacts 76A. The alarm lamp 72A is consequently ionized in order to provide a visually observable signal and initiate a controlled transient electric current. The transient discharging current which is drawn through grid resistor 84 thus produces a negative grid potential which terminates conduction through the discharge device 82.

At this point, the interruption of current through coil H with consequent opening of contacts H and closure of contacts H causes the alarm horn 90 to receive power in the same manner as discussed in connection with the circuitry shown in FIG. 2. I

In FIG. 4A, the negative pulse which appears at the grid of the device 82 under alarm conditions is shown whereas in FIG. 4B, the positive pulse which appears at the control grid when an alarm condition clears is illustrated.

Generally, when a given point indicates an alarm condition, the associated alarm lamp is energized, and an acknowledgment must be effected by depressing the push button switch 62. If any other point in the system should alarm while the original point is returning to normal, the present circuitry actuates an alarm sequence and indicates the occurrence of a new hazardous condition. This is because the newly produced negative pulse applied to the grid of the space discharge device cannot be cancelled out or nullified by the positive pulse which accompanies the clearing of the previously hazardouscondition.

FIG. 4C illustrates a composite wave form of the electrical pulse appearing at the grid of discharge device 82 when an alarm conditionoccurs-at the instant another alarm condition is clearing. It will be observed that the differences in timeconstants renders possible the initiation of a new alarm condition during the time interval in which positive charging current in the grid resistor indicates the clearing of the pnevious condition. The peaked negative pulse in FIG. 4C will be seen to appear at the control grid of the space discharge device in full strength, although characterized by a shorter time constant on the trailing edge.

It will now be evident that the occurrence of a fresh alarm condition during the restoration of a previous dangerous condition to normal will positively actuate the alarm horn or other type indicator employed in practicing the invention.

By means of the circuitry in FIG. 5, it is possible for operating personnel to discover which of the variables in a complicated system of inter-related variables first deviated oft-normal into a hazardous range of values.

In this figure, the reference numeral 92 has been used to designate a tapped voltage supply provided with a grounded negative terminal. The common bus 70 is coupled to a positive 200 volt tap by means of a set of normally open contacts H The common bus 70 is also coupled to a positive 90 volt tap via a set of normally closed contacts H Contacts H and H; are of the variety known in the art as make-before-break contacts.

. The closure of a pair of alarm contacts such as 76A causes the charging current through resistor 84 to terminate conduction in tube 82 in exactly the same mann'er as described in connection with FIG. 3. However, the loss of excitation in relay operating coil H causes contacts H, to close and contacts H; to open. At this time, all other alarm lamp circuits are rendered inoperative because of the action of the make-before-break contacts H and H in reducing the voltage supplied to the remaining lamps. Until such time as relay operating coil H is re-energized by depressing the push button switch 62, all other alarm lamps are caused to remain de-energized even though one of the associated set of alarm contacts might attempt to indicate an alarm condition. By this means, the first cause of trouble detected by a group of sampling instruments is indicated conclusively, with consequent opportunity for eliminating all other alarm conditions by rapidly correcting the first of the variables to experience the hazardous range of values.

While several embodiments of the invention have been shown and described herein, it will be apparent to those skilled in the art that the structure and arrangement of the elements of the present invention may be changed or modified without departing from the spirit and scope of the appended claims.

I claim:

1.- In a system for providing an observable indication of the occurrence of alarm conditions; a voltage supply provided with a grounded positive terminal; a plurality of individual circuits connected each at one end to the negative terminal of said supply, each of said circuits including a series connected resistor and capacitor with an ionizable device and a normally closed condition responsiveswitch means connected to ground therebetween; a normally conducting space discharge device provided with a grounded cathode said device being made nonconductive in response to opening of said switch means, a grounded grid resistor, and a \grid electrode connected in common with the other end of each of said individual circuits; means including relay means connected responsive to non-conduction through said discharge device and conduction through said ionizable devices for initiating said indication of alarm conditions; and an alarm circuit operatively connected to and activated by said relay.

2. In a system for providing an observable indication of the occurrence of alarm conditions; a voltage supply provided with a grounded negative terminal and at least one positive terminal; a plurality of individual circuits connected at one end to receive positive potential from said supply, each of said circuits comprising an ionizable device, a resistor, and a capacitor coupled in series, with a normally open condition responsive switch means connected between ground and the side of said capacitor adjacent said resistor; a normally conducting space discharge device provided with a "grounded cathode, said device 'being made non-conductive in response to closure of said switch means, a grounded grid resistor, and a grid electrode connected in common with the other end of each of said individual circuits; means including relay means connected responsive to non-conduction through said discharge device and conduction through said ionizable device for initiating said indication of alarm condition-s; and an alarm circuit operatively connected to and activated by said relay.

3. In a system for providing an observable indication of the occurrence of alarm conditions, a power supply providing a first voltage and a second voltage having a magnitude less than said first voltage, a plurality of individual circuits adapted to be selectively connected at one end to one of said first and second voltages, each of said circuits comprising an ionizable device, a resistor, and a capacitor coupled in series, with a normally open condition responsive switch means connected between ground and the side of said capacitor adjacent said resistor; a space discharge device provided with a grounded cathode, a grounded grid resistor, and a grid electrode connected in common with the other end of each of said individual circuits, an alarm circuit operatively connected to said device and activated in response to non-conduction or" said device, and means operatively connected to said device and responsive to conduction of said device to connect said first voltage to said individual circuits and responsive to non-conduction of said device to connect said second voltage to said individual circuits.

4. A signalling system including power supply means; a plurality of detection circuits connected in parallel and connected to said power supply means, each detection circuit including a switch means and an ionizable device, each of said detection circuits supplying a voltage pulse in response to operation of its switch means and ionization of its ionizable device; a normally conducting device; means connecting said plurality of detection circuits to said conducting device to apply said voltage pulse to said conducting device, said conducting device being made non-conducting at least momentarily in response to said voltage pulse; and an alarm circuit operatively connected to and activated in response to non-conduction of said conducting device.

5. The invention defined in claim 4, wherein each of said detection circuits further includes a resistor connected to limit current flow through said ionizable device upon ionization thereof.

6. The invention defined in claim 4, wherein each of said detection circuits further includes a resistor connected to limit current flow through said ionizable device upon ionization thereof, and further wherein, in each of said detection circuits, said ionizable device, said switch means and said resistor are connected in series across said power supply means.

7. The invention defined in claim 4, wherein each of said detection circuits further includes a resistor connected to limit current flow through said ionizable device upon ionization thereof, and further wherein, in each of said detection circuits, said ionizable device and said resistor are connected in series across said power supply means and said switch means is connected in parallel with said ionizable device.

8. A signalling system including power supply means; a detection circuit connected to said power supply means, said detection circuit including an ionizable device, a resistor connected to limit current flow through said device upon ionization, and switching means operable to connect said ionizable device to said power supply means to cause said device to ionize; a normally conducting space discharge device; a capacitor connected between said space discharge device and said detection circuit; a resistor having one end connected to said capacitor and said space discharge device and having the other end connected to said power supply means, said capacitor and said last-mentioned resistor providing a voltage pulse in response to ionization of said ionizable device to cause said space discharge device to cease conducting at least momentarily in response to said voltage pulse; and an alarm circuit operatively connected to and activated in response to non-conduction of said space discharge device.

9. The invention defined in claim 8, wherein, in said detector circuit, said ionizable device, said resistor and said switch means are connected in series across said power supply means.

10. The invention defined in claim} 8, wherein, in said detector circuit, said ionizable device and said resistor re connected in series across said power supply means and said switch means is connected in parallel with said ionizable device.

11. A signalling system including power supply means providing a first voltage and second voltage having a magnitude less than said first voltage; a plurality of detection circuits, each detection circuit including a switch means and an ionizable device, said ionizable device being ionized upon closure of said switch means provided said first voltage is applied to said detection circuit and remaining ionized when said second voltage is applied to said detection circuit while said ionizable device is ionized; a normally conducting device; a plurality of pulse-forming circuits, one connected to each detection circuit and connected to said normally conducting device, each pulse-forming circuit providing a voltage pulse in response to ionization of the ionizable device in the corresponding detection circuit to cause said normally conducting device to cease conduction in response to said voltage pulse; means operatively connected to said normally conducting device and responsive to the conducting condition of said normally conducting device to connect said first voltage to said plurality of detection circuits only during conduction of said normally conducting device and to connect said second voltage to said plurality of detection circuits only during non-conduction of said normally conducting device, and an alarm circuit operatively connected to and activated in response to non-conduction of said normally conducting device.

12. The invention defined in claim 11, wherein each of said detection circuits further includes a resistor connected to 'limit current flow through said ionizable device upon ionization thereof.

13. The invention defined in claim 11, wherein each of said detection circuits furtherincludes a resistor connected to limit current flow through said ionizable device upon ionization thereof, and further wherein, in each of said detection circuits, said ionizable device, said switch means and said resistor are connected in series across said power supply means.

References Cited in the file of this patent UNITED STATES PATENTS 2,535,133 Hoch Dec. 26, 1950 2,556,363 Lord June 12, 1951 2,611,017 Bailey Sept. 16, 1952 2,695,400 Snitjer Nov. 23, 1954 2,715,720 Henkins Aug. 16, 1955 2,724,109 Skolnick et al. Nov. 15, 1955

Claims (1)

1. IN A SYSTEM FOR PROVIDING AN OBSERVABLE INDICATION OF THE OCCURRENCE OF ALARM CONDITIONS; A VOLTAGE SUPPLY PROVIDED WITH A GROUNDED POSITIVE TERMINAL; A PLURALITY OF INDIVIDUAL CIRCUITS CONNECTED EACH AT ONE END TO THE NEGATIVE TERMINAL OF SAID SUPPLY, EACH OF SAID CIRCUITS INCLUDING A SERIES CONNECTED RESISTOR AND CAPACITOR WITH AN IONIZABLE DEVICE AND A NORMALLY CLOSED CONDITION RESPONSIVE SWITCH MEANS CONNECTED TO GROUND THEREBETWEEN; A NORMALLY CONDUCTING SPACE DISCHARGE DEVICE PROVIDED WITH A GROUNDED CATHODE SAID DEVICE BEING MADE NONCONDUCTIVE IN RESPONSE TO OPENING OF SAID SWITHCH MEANS, A GROUNDED GRID RESISTOR, AND A GRID ELECTRODE CONNECTED IN COMMON WITH THE OTHER END OF EACH OF SAID INDIVIDUAL CIRCUITS; MEANS INCLUDING RELAY MEANS CONNECTED RESPONSIVE TO NON-CONDUCTION THROUGH SAID DISCHARGE DEVICE AND CONDUCTION THROUGH SAID IONIZABLE DEVICES FOR INITIATING SAID INDICATION OF ALARM CONDITIONS; AND AN ALARM CIRCUIT OPERATIVELY CONNECTED TO AND ACTIVATED BY SAID RELAY.

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