US2646556A - Supervised alarm system - Google Patents

Description

July 21, 1953 F. B. ALLEN suPERvIsED ALARM SYSTEM Filed Jung 17, 195

IN V EN TOR. FQANK B. A1. 4 e/v A Tron/EX Patented July 21, 1953 y SUPERVISED ALARM SYSTEM Frank B. Allen, Towaco, N. J., assignor to C-O- Two Fire Equipment Company, Newark, N. J., a corporation of Delaware Application June 17, 1950, Serial No. 168,706

4 Claims. l

This invention relates to supervised alarm systems and more particularly to a system for use with a detector such as the ionization type wherein thereis no current ilow through the detector until a predetermined condition has occurred.

A system of the type to be described may be used for re o1' smoke detection and may utilize an ionization detector. In the ionization detector a reference chamber and a test chamber have spaced electrodes upon which a predetermined potential diference is maintained, the air in both of the chambers being ionized by the presence of a radioactive material, the apparatus being constructed so that upon the entry into the test chamber of a uid such as. smoke the balanced condition is affected and an electronic relay is actuated to provide an alarm.

In the event the detector is used to indicate fire or smoke, it is important that supervisory means be continuously operable to ascertain any failure in the system such as a broken wire or the removal of a detecting unit. As a detector of this sort draws practically no current until an unbalance has occurred resulting from the disturbance of the ionization condition in the test chamber, there is no current flow and thus it is difficult to supervise the condition of the circuit.

The present invention aims to provide a supervised alarm circuit for use with a detector normally drawing practically no current.

Another object of the invention is to provide a supervised alarm circuit having means to indicate the failure of the source of electrical energy.

It is also an object of the invention to provide y means to indicate a short circuit occurring in the detector circuit.

Another object of the invention is to provide means to indicate the removal of a detector unit from its mounting base.

A still further object of the invention is to provide a supervised alarm system which is simple and economical in manufacture and eicient in operation.

A circuit in accordance with the invention is advantageous as it permits the use of an adaptor and testing means for the adjustment of the detector in the position in which it is to be used.

Other objects and advantages of the invention will be apparent from the following description and from the accompanying drawing which shows, by way of example, an embodiment of the invention.

In the drawings:

Figure 1 is a diagrammatical representation of 2 1 a supervised alarm system constructed in accordance with the invention.

Figure 2 is a diagrammatical representation of an individual detector circuit used in the system shown in Figure 1.

Referring to the drawings, there is shown' a supervised alarm system in accordance with the invention connected to a source of alternating current supply I through atransformer Il. The alternating lcurrent supplied by the transformer II is converted to direct current by the rectifier I2 and ltered in the circuit I4 after which it isY passed through a relay coil I5 connected in series with a plurality of detector unitsl and thence to ground. As shown in the drawing, the detector units IB are connected together for usein a single zone and a plurality of parallel connections may be made to other detectors likewise connected in one or more other zones.

The transformer II is preferably of the regulator type producing a constant output voltage irrespective of minor variations in its input voltage. A primary winding I'I of the transformer II is connected through a switch I9 and a fuse to the source of alternating current supply I0. A secondary heater winding 2l is connected to a heater filament 22 of the full-wave rectifier tube I2. A secondary load winding 24 of the transformer II has its midpoint 25 grounded and its outside leads 26 and 2 connected to anodes 29; and 3D of the full-wave rectifier I2. A cathode 3| of the full-wave rectier tube I2 is connected in series by a wire 32 to the lter I4 including an inductance 34 across the ends of which are connected a pair of grounding condensers 35. The output of the lter I4 is connected by a wire 35 in series with the coil I5 of a supervisory and alarm relay 31 having a pair of double-throw contacts and 48a. The outgoing lead of the relay coil I5 is connected by a wire 4I from which the detector units I6 are connected in parallel by wires 42. The detector units I6 are supported by mounting brackets 44 each made with 44. The detector unit I6 includes a control ionization chamber and a test ionization chamber 56, chamber 55 being vented to the atmosphere through a small aperture I in its wall for equalization of the control chamber pressure and the atmosphere pressure, while chamber 56 has a comparatively large opening 59 for the easy movement of air to be tested through the charnber. The control ionization chamber 55 has its outer wall 69 forming an electrode connected by a wire 6I to terminal 52 of the base 54. An intermediate insulated portion 64 carries a partition 65 having thereon a small portion of radioactive material 66 which provides for the ionization of the air in the control chamber 55 and in the test chamber 56. The test chamber 56 has its outer wall forming an electrode 61 connected by a wire 69 to terminal 5I of its base. Within the chambers 55 and 56 are positioned electrodes I0 and '|I both spaced from the walls of their respective chambers and insulated therefrom and connected by a wire 'l2 to the control electrode 'I3 of a cold cathode tube '14. Plate 'I5 of the cold cathode tube 'I4 is connected to the wire 6I and a second plate 'I6 is connected to the wire 69 thereby connecting the cold cathode tube in parallel across the two chambers 55 and 56. The ionization chambers and the cold cathode tube are mounted in a suitable casing on the base 54 to provide a detector assembly easily removable or replaceable, if desired.

In the event a single detector unit I6 is to be used in a zone, its terminal 41 is grounded, while if a plurality of units are to be used in a zone, a ground wire TI is connected to the terminal 46 of the last detector providing a series ground connection through all of the detector units in one zone. The mounting brackets have their terminals and 4l' connected by jumpers 'I9 while the detector bases 54 have their terminals 49 and connected by jumpers 86. A series connection between each detector is provided by connecting terminal 46 of the rst detector unit by a wire 8| with terminal 41 of the next unit and making like connections between each of the detector units I6. By this means a series connection is made through each detector unit I6 to ground so that the removal of one of the detector units will indicate an open circuit and produce a trouble signal.

The movable contact 40 of the supervisory and alarm relay 31 is used to complete a circuit to provide an indication of a zone in which re or other conditions is present. Movable contact 40 is connected by a wire 84 to one side of the supply transformer coil I`| while xed Contact 39 is connected by a wire 86 to a zone indicator 9T having its other terminal connected by wire 89 to the other side of the coil I'I of the supply transformer. The other fixed contact 38 is connected in parallel with the fixed contact 39.

The double-throw contact 49a is connected to one side of the source of supply through the wire 84. Fixed contact 9| is connected through a wire 92 to one side of the coil 94 of an alarm relay 95, the other side of the coil 94 is connected to the other side of the source of supply by a wire 96. Fixed contact 91 of the double-throw contacts 40a is connected by a wire 99 to one side of a trouble buzzer |09. The other side of the trouble buzzer is connected by the wire 89 to one side of the coil II of the power supply. The alarm relay 95 has additional contacts IDI and |02 which may be connected in a circuit with alarm gongs to a central station, or to initiate the discharge of a fire extinguishing system.

The supervisory and alarm relay 37 preferably has a wound armature so that its contacts may be positioned depending upon the current flow through the relay coil I5. Under conditions of no current or under a predetermined minimum current flow, the armature moves to connect contact 40a with 91 to give a trouble alarm, and contacts 49 and 39 are connected to give a zone indication. For a greater current flow through the relay coil I5, the armature changes the position of the movable contacts to a floating position between the fixed contacts. Under conditions of a still greater current, the armature causes the movable contacts to move upwardly to connect contacts 39 and 49 for the zone indicator 81 and to connect contacts 40 and 9| to the fire alarm relay 95. In order to produce suicient current flow to maintain the movable contacts iloating during normal operation of the system, a resistor |04 is connected between the wire 4| and the terminal 45 of the detector mounting base by a wire I 65. A circuit is then provided drawing a predetermined minimum current through the relay coil I5 so as to hold the contacts away from the trouble position.

In operating a system in accordance with the invention, it is connected to a source of alternating supply ID thereby energizing the transformer I I and high voltage is applied to the plates ol the rectifying tube I2. The output of the rectiying tube I2 passes through the iilter |4, through the coil I5 of the supervisory relay S1, through the resistor |94, the jumper connection 'I9 of the mounting block, through the jumper connection 89 of the detector base, and through wires 8|, and to ground through connection 11.

In the event any of the detectors i5 are removed from their mounting bracket 44, the circuit for the resistor |84 is opened thereby causing the supervisory relay to cause the trouble alarm to be given. Likewise, if an open circuit occurs in the wiring to the detector unit I6, the current through the relay coil I5 drops to zero causing the trouble alarm to be sounded and causing a zone indication. A failure of the alternating current supply likewise causes the relay to drop to the trouble position.

In the event a condition is present, such as nre, causing an unbalance of the ionization chambers 55 and 56, the cold cathode tube 'i4 is triggered to break down and cause an increased current ow through the relay coil l5 thereby producing a iire alarm and zone indication. Further, in the event a short circuit occurs in the detector or zone wiring an alarm signal is given.

In order to adjust or set the detector I6 for any predetermined condition, an adaptor jack (not shown) may be interposed between the detector base 54 and the mounting bracket di@ thereby providing for connections to adjust the detector while it is positioned in the space wherein it is to be used.

It conditions warrant the installation of one or more additional zones, connections thereto may be made in parallel to wires E4, 92, 69 and 86 as indicated at |98, and an additional zone indicator |06 may be connected by a wire I i.

From the foregoing description it may be seen that a supervised alarm system has been provided for use with a detector normally drawing practically no current. Supervision is given of the `failuze of the power supply, the presence of a short circuit, the presence of re and an indication of the removal of one of the detector units.

While the invention has been illustrated and described with reference to a specific embodiment thereof, it will be understood that other embodiments may be resorted to without departing from the invention. Therefore, the form of the invention set out above should be considered as illustrative and not as limiting the scope of the liollowing claims.

l claim:

1. An electrically actuated alarm system comprising an alarm signal to indicate a predetermined condition, a trouble signal to indicate malfunctioning of the system, single relay means to close a circuit to the trouble signal for a current now below a minimum amount and to open the trouble circuit for a current flow above the minimum amount and to close a circuit to the alarm signal for a current lorw of the same polarity above a predetermined amount, a resistor in series with the relay means to provide a current ow above the minimum amount to open the trouble signal circuit, a detector connected in parallel with the resistor and responsive to a predetermined condition to provide a current flow above the predetermined amount to close the alarm circuit, a mounting bracket for the detector carrying a pair of contacts connected in series, a base for the detector, and a second pair of contacts connected in series and carried by the base, whereby when the detector is in position on the mounting block the two `pairs of contacts are in series.

2. An electrically actuated alarm system comprising an alarm signal to indicate an ionization condition, a trouble signal to indicate malfunctioning of the system, a relay switch having a set of double-throw contacts, one set of contacts connected to the alarm signal and the other set connected to the trouble signal, a single relay coil to actuate the relay switch, the relay switch constructed and arranged to close the trouble contacts for a current flow through the relay coil below a minimum amount and to open the trouble contacts for a current flow of the same poiarity above the minimum amount and to close the alarm contacts for a current flow above a predetermined amount, a resistor in series with the relay coil to provide a current flow above the minimum amount to open the trouble signal circuit, a detector connected in parallel with the resistor responsive to an ionization condition to pass current to provide a current flow above the predetermined amount to close the alarm circuit, a mounting bracket for the detector, a pair of contacts on the mounting bracket in series with the relay coil, a base for the detector, and a pair of series-connected contacts on the base, the base series contacts adapted to coact with the bracket contacts to complete the relay circuit to the resistor and the detector whereby a trouble its bracket.

3. An electrically actuated alarm system comprising alarm sign-al means to indicate a predetermined condition, a trouble signal to indicate malfunctioning of the system, a circuit adapted to be connected to a source of electric current, a resistor connected across the circuit to draw a predetermined current therethrough, a detector responsive to the predetermined condition to provide additional current through the circuit of the same polarity as the current through the resistor, rst switch means, a set of double-throw contacts for the first switch means, one set of contacts connected to the alarm signal and the other set connected to the trouble signal, second switch means, a set of double-throw contacts for the second switch means, a zone indicator, both of said second sets of double contacts connected` to the zone indicator, and single relay means responsive to the current in the circuit to close the trouble switch for a current flow below a predetermined minimum amount and to close the alarm switch upon the flow of a predetermined additional amount of current and to close one set of the zone indicator switch contacts with the alarm contacts and the other set of zone contacts with the trouble contacts so that the location of the condition or trouble is given.

4. An electrically actuated alarm system comprising alarm signal means to indicate a predetermined condition, trouble signal means to indicate malfunctioning of the system, electric circuit connection means, relay means to operate the signals, la resistor connected in the circuit in series with the relay to draw a predetermined current therethrough for normally preventing actuation of the trouble signal means, a detector responsive to the predetermined condition to provide additional current through the relay of the same polarity as the current through the resistor for the actuation of the alarm signal, a mounting bracket for the detector, a pair of contacts carried by the mounting bracket and connected in series with the resistor, a base for the detector, and a pair of contacts connected in series and carried by the base, the base contacts cooperating With the bracket contacts to complete the circuit through the resistor, whereby upon the removal of the detector and its base the trouble signal is actuated.

FRANK B. ALLEN.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date.

1,229,939 Goldstein June 12, 1917 1,909,212 Muehter May 16, 1933 2,000,074 Grant, Jr. May 7, 1935 2,473,940 Clark June 21, 1949

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