US2938197A - Automatic alarm transmitter - Google Patents

Description

May 24, 19 J. 1.. CASSELL AUTOMATIC ALARM TRANSMITTER 3 Sheets-Sheet 1 Filed Sept. 14, 1954 INVENTOR. JOSEPH L. CASSELL ATTORNEY May 24, 1960 J. CASSELL AUTOMATIC ALARM TRANSMITTER 3 Sheets-Sheet 2 Filed Sept. 14, 1954 l-OS FIG.3

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mmvron JOSEPH L. CASSELL ATTORNEY May 24, 1960 .1. 1.. CASSELL AUTOMATIC ALARM TRANSMITTER 5 Sheets-Sheet 3 Filed Sept. 14. 1954 FIG. e

FIG.7

L R RS 05 TA MC L m a Q J ATTORNEY 2,938,197 AUTOMATIC ALARM TRANSMITTER Joseph L. Cassell, New York, N.Y., assignor to Automafic Fire Alarm Company, New York, N.Y., a corporation of New York Filed Sept. 14, 19 54, Ser. No. 456,033

12 Claims. 01. 340-288) The invention herein disclosed relates to signaling apparatusparticularly for transmitting coded signals to a central oifice.

While of special importance for fire alarm systems, the invention is not limited to that field but may be applied to burglar alarm systems or other types of signaling equipment.

mitter itself may be built in a single standard form, and

then just before being connected for service or possibly just before shipment from the factory, may be quickly and conveniently arranged to provide the proper retard time either for the waterflow or for the aero type of fire alarm system.

Actuallythis final provision of the proper retard interval may be determined by the simple expedient of selecting and applying a nameplate either of non-conductive or conductive material and which in the first instance will leave a normally charged capacitor free to discharge for the full retard time, say thirty seconds for a Waterfiow system, or in the second instance will shunt a resistance across the capacitor to reduce the retard time, say to twelve seconds for an aero or other such system.

Other special features and objects of the invention relate to the so-called fire clock and trouble clock and to the maintaining of these in cooperative but independently active relation, the fire clock being capable at all times of sending in a fire signal and the trouble clock capable at all times of signalling a break or ground, or both, and further, in the event of a break or a ground, automatically establishing a special trouble circuit condition after transmission of the trouble signal which special circuit condition permits the fire clock to operate in response to an alarm signal notwithstanding the presence of the open circuit or ground condition on the protective circuits.

7 Other features of the. invention relate to the tamper switch which is held closed by the door of the enclosure in which the transmitter is" mounted and which through the cooperating of certain cam mechanism of the trouble clock, enables the door to be completely closed before the trouble clock, after having been fully wound with the door open, can run down beyond its starting condition.

.Another important feature of the invention is the provision of a rectifier protecting the capacitor against damage from reversal of polarity and insuring that the transmitter, after installation and inspection, will always be ,left with the current supply connected in the correct polarity for normal operation of the system.

Other special features of the'iuvention relate to con- Unitecl States Patent 2,938,197 Patented May 24, 1960 2 trol relays and circuits,'one instance in particular in which a current relay transfers the central oflice wires to a current failure signal wheel on the fire clock, thus to prevent a clash of signals which might otherwise result from simultaneous operation of the trouble clock with the fire clock, on loss of supply current.

Other desirable objects and novel features of the invention are set forth and will appear in the course of the following specification.

' The drawings accompanying and forming part of the specification illustrate a present practical embodiment of the invention and circuit connections applicable thereto. Construction, combination and relation of parts, however, may be modified and changed as regards the immediate illustration, all within the true intent and scope of the invention as hereinafter defined and claimed.

Fig. 1 in the drawings is a front or face view of the bare transmitter, that is, the insulating panel forming the base of the instrument and the various mechanical and electrical parts mounted on the panel, all constitut- Lug a single unit adapted to be mounted in an alarm Fig. 2 is a circuit diagram of parts shown in Fig. 1;

Fig. 3 is a simplified diagram illustrating action of the transmitter in a typical alarm system;

Figs. 4 and S are fragmentary sectional detail views taken on the line 4-4 of Fig. 1, showing the selective use of metal and insulating nameplates to control the retard time.- I

Figs. 6 and 7 are fragmentary perspective views illustrating control features of the fire clock and trouble clock, respectively.

In Fig. 1, there is shown a total of sixteen screw type terminals numbered 1 to 16, mounted on a panel 18 of suitable insulating material. Near the corners of the panel 18 are mounting screws 19 for securing the panel in a suitable protective enclosure such as a metal cabinet (not shown). This cabinet will ordinarily be provided with a hinged door for access to the transmitter, provision being made for locking the door in its closed position. A tamper switch 20 is actuated by the door. The tamper switch 2%) is a three position switch having two closed positions and a single open position. With the cabinet door closed, the tamper switch 20 is closed as shown'in Fig. 2. When the cabinet door is opened, the tamper switch 20;is automatically spring pressed to its open position. With the door open, the tamper switch may be manually operated to its closed position for 'purposes of testing and maintenance.

Mounted on the face of the panel 18 are two spring driven clockwork mechanisms one being a fire clock designated generally as 1-00 and the other a trouble clock designated generally as 2-00. These mechanisms are provided with key operable winding stems 1-01, 201, escapements 1-02, and 2-02 and release magnets 1-03 and 24B, respectively. The release magnets 103 and 2-03 are provided with colresponding operating windings 1-04 and 2-04 (Fig. 2).

The fire clock 1-00 is shown, Figure 6, as having a front code wheel 1-05 and a rear code wheel 1-06 mounted on a common code 'wheel shaft 1-07. The front code wheel 1-05 controls a set of contact springs 1-08 and the rear code wheel 1-06 controls a set of contact springs 1-09. The fire clock 1-00 also comprises a reduced speed cam shaft 1-10 which is driven along with the code wheel shaft 1-07 by the clockwork mechanism. The cam shaft 1-10 will ordinarily revolve at one-fifth of the speed of the code wheel shaft 1-07. The cam shaft 1-10 carries a cam 1-11 formed of insulating material. Shortly after the beginning of operation of the fire clock mechanism, the cam 1- 11 will close two pairs of contact springs 1-12 and ;1-.13

and a cam 2-06 mounted on a common code wheel shaft 2-07. The code wheel '2-05 controls a set of contact springs 2-08. The cam 2-06 controls a set ofcontact springs 2-09. There is also a radially proiectingarrn 2-10 mounted on thespring winding shaft 2-01. The

arm 2-10 is arranged to. actuate contact springs after the trouble clock 2-00 has unwound to the extent of completing its signal transmission cycle. There are two pairs of normally .open run-down contacts 12-11 and 2-12 which are closed by the arm 2-10 and two pairs of normally closed run-down contacts 2-13 and 2-14 which are opened by action of the arm 2-10 when the trouble clock 2-00 is unwound.

As shown in Fig. 1, there is an electrolytic capacitor 36, mounted on the front of the panel 18 between the fire clock 1-00 and the trouble clock 2-00.

Mounted on the upper portion of the panel 18 are three relays. An alarm relay 3-00 is located above the fire clock 1-00. A trouble relay 4-00 is located above the trouble clock 2-00. A power failure or current supply supervisory relay 5-00 is located above the capacitor 36.

The alarm relay 3-00 comprises an operating winding 3-01 and a single pair of contacts 3-02. The operating winding 3-01 is normally energized holding the contacts 3-02 normally closed. Upon deenergization of the operating winding 3-01, the alarm relay contacts 3-02 will open.

The trouble relay 4-00 comprisw an operating winding 4-01 and a single set of transfer contacts consisting of a movable or transfer contact 4-02, a contact 4-03 which is engaged by contact 4-02 when the winding 4-01 is energized and a contact 4-04 which is engaged by the movable contact 4-02 when the winding 4-01 is deenergized.

The power failure or current supervisory relay 5-00 comprises an operating winding 5-01, two sets of transfer contacts and a further set of contacts. One set of transfer contacts comprises a movable contact 5-02 which engages a contact 5-03 when winding 5-01 is energized and engages another contact 5-04 when the winding 5-01 is deenergized. The other set of transfer contacts comprises a movable contact 5-05 which engages a contact 5-06 when the winding 5-01 is energized and engages another contact 5-07 when winding 5-01 is deenergized. The further set of contacts 5-08 is closed when the winding 5-01 is energized.

In the face view of the transmitter givenin Fig. 1

all of the apparatus is shown in its completely decnergized condition. All relay windings are deenergized. Both of the clock mechanisms 1-00 and 2-00 are unwound. The arm 2-10 is shown actuating the run down contact springs so as to close the normally open run-down contacts 2-11 and 2-12 and to open the normally closed run-down contacts 2-13 and 2-14.

In Fig. 2, the apparatus is shown in its normal operative condition, ready to transmit either a fire signal or a trouble signal. 7

In in this view, terminals 7 and 8 are indicated as being connected to a suitable source of 12 volts direct current illustratively shown as an ungrounded battery 21, Fig. 3. The operating winding 5-01 of the power failure or current supervisory relay 5-00 is connected directly to the supply terminals 7 .and 8 so that it is continuously energized so long as there is no failure of the 12 volt supply 21. The operating winding 1-04 for the release magnet 1-03 of the fire clock 1-00 is connected directly in series with the contacts 5-08 of the power failure relay 5-00 so that the fire clock will be tripped immediately in the event of current failure. The movable transfer contacts 5-02 and 5-05 of the power failure relay 5-00 are connected directly by conductors 22 and 23 to panel terminals 11 and 12 which, in turn, are connected to a conventional McCullogh central oflice circuit 24 which is normally closed. Under normal conditions, conductors 22 and 23 are connected through relay con tacts 5-02, 5-03 and 5-05, 5-06 to the serially connected code-wheel actuated contact springs 1-08 and 2-08 of the fire clock and trouble clock 1-00 and 2-00, respec- "tively. The sets of contact springs 1-08 and 2-08 are connected in series with each other and are actuated by the code wheels 1-05 and 2-05, respectively, for the separate transmission of fire alarm and trouble signals with power from battery 21 available at panel terminals 7 and 8. Upon power failure, however, the central office circuit 24 is transferred via relay contacts 5-02, 5-04 and 5-05, 5-07 to the contact springs 1-09 of the fire clock which are actuated by the special power failure signal code wheel 1-06 of the fire clock 1-00. As previously noted, the circuit of the operating winding 1-04 of the release magnet 1-03 of the fire clock 1-00 is opened simultaneously with the transfer of the central oflice circuit to the special power failure signal contacts 1-09 so that the power failure signal is transmitted immediately by the fire clock mechanism 1-00. During power failure conditions with the relay 5-00 released, the fire signal codewheel contacts 1-08 and trouble signal code-wheel contacts 2-08 are both completely disconnected from the central oflice circuit 24. It will be noted that this circuit is normally ungrounded and that the grounding only occurs when the first tooth of the code wheel touches the actuating spring.

Under normal conditions, the negative side of the 12 volt supply 21 at panel terminal 7 is connected to ground through panel terminals 9 and 10 by the normally closed run-down contacts 2-13 of the trouble clock 2-00. Thus, under normal conditions, the negative side of the 12 volt power supply is grounded. The negative panel terminal 7 is connected by a conductor 25 to one side of the operating winding 4-01 of the trouble relay 4-00. The operating winding 4-01 is the last circuit element connected to the negative supply conductor 25 so that any break in conductor 25 which would render other circuit elements inoperative will also deenergize the trouble relay 4-00 and cause a trouble signal to be transmitted.

The positive panel terminal 8 is continuously connected to the other side of the winding 4-01 of trouble relay 4-00 by a supervisory circuit which is traceable via a conductor 27 and through a resistor 28 to the panel terminal 5. From terminal 5, the circuit extends over a house loop conductor 46 and back to panel terminal 4. From terminal 4, the circuit extends locally at the transmitter panellB through the operating winding 3-01 of the alarm relay 3-00 and a resistor 29 to panel terminal 1. From panel terminal 1, the supervisory circuit extends through the tamper switch 20 to panel terminal 2 and through a jumper from panel terminal 2 to terminal 3'. From panel terminal 3, the closed supervisory circuit continues over another house loop conductor 45 to panel terminal 6 and from terminal 6 via a conductor 30 to the positive side of winding 4-01 of the trouble relay 4-00. Obviously, any break in this closed supervisory circuit will deeuergize the winding 4-01 of trouble relay 4-00. Similarly, a ground on any portion of this supervisory circuit from panel terminal 8 to the positive side of trouble relay winding 4-01 will deenergize winding 4-01 and actuate the trouble relay 4430 because the negatit e side of winding 4-01 is grounded through trouble clock run-down contacts 22-13 as described above.

The two house loop conductors 45 and 46 thus form a two-wire circuit through which the supervisory circuit extends from the panel 18 to the contacts of an alarm signal device 47 and back to the winding 3-01 of the alarm relay. The alarm signal device comprises normally open contacts connected between the two sides of the and the transmitter will be inoperative. will observe this situation and reverse the connections at I double ended' loop or two-wire circuit portion of the supervisory circuit constituted by the house loop conductors 45 and 46. The alarm switch 47, which may illustratively be considered to be operated by water flow actuated means in an automatic sprinkler system, whenoperated, will connect house loop conductors 45 and 46 together so that the winding 3-01 of the alarm relay 3-00 is shunted and the alarm relay 3-00 then releases opening its contacts 3-02.

Opening of alarm relay contacts 3-02 interrupts an energizing circuit for the winding 1-04 of fire clock release magnet 1-03. This energizing circuit extends from the positive supply conductor 27, alarm relay contacts 3-02, a conductor 33, a rectifier 44 and power failure relay contacts 5-08 to the positive side of release magnet winding 1-04. The negative side of the release magnet winding 1-04 is permanently connected to negative panel terminal 7 by the negative supply conductor 25. However, interruption of this energizing circuit does not immediately release the magnet 1-03 because its winding 1-04 continues to receive current from the charged capacitor 36 through a resistor 31. The discharge path of capacitor 36 consists solely of the fire clock release magnet winding 1-04 and the total resistance of this winding and resistor 31'is sufficiently high so that the clock 1-00 will not transmit the fire signal until a delay of about 30 seconds has elapsed from the instant of opening of the alarm relay contacts 3-02. It will be observed the capacitor 36 is normally continuously energized through the closed contacts 3-02 of the alarm relay 3-00 through conductor 33 and the series resistor 31 so that it is always ready to continue the energization of the fire .clock release magnet winding 1-04 for a thirty second interval following the opening of alarm relay contacts 3-02. This thirty second interval of prolonged energization has been found to be satisfactory in practice to prevent the transmission of false fire alarm signals as a result of water hammer effects in -the automatic sprinkler system which causes closure of the contacts of the alarm signal device 47. The resistor 31 in series with capacitor 36 is a current limiting resistor which prevents excessive current flow through relay contacts 3-02 or 4-02, for example, during charging and discharging of the capacitor and particularly in the event of an accidental short circuit caused by dielectric failure within the capacitor.

-Additionally, if the electrolytic capacitor 36 should break down, resistor .31 prevents short-circuiting of the fire clock-release magnet winding 1-04 and thus avoids the transmission of a false fire signal.

The rectifier 44 serves as a protective device to prevent damage to the capacitor 36 by any inadvertent connection of the power supply to panel terminals 7 and 8 with reversed polarity. In such event, the rectifier prevents sufficient reverse current flow to damage the electolytic capacitor 36 and the current flow through the winding '1-04 of'the fire clock release magnet 1-03 is insufiicient to'en'ergize the release magnet. As a result, the fire clock magnet 1-03 will remain released with reversed polarity The installer panel terminals 7 and 8 in order to obtain the correct polarity and proper operation of the transmitter.

Fire signal transmission In the event of fire, water flow in the sprinkler system will cause the contacts of the. alarm signal device 47 to close and to remain closed continuously during period of water flow. Closure of the contacts of the alarm signal device 47 connects thehouse loop conductors 45 and 46 together and thereby shunts out the operating winding 3 -01 of the alarm relay 3-00. Current fiow through the operating winding 4-01 of the trouble relay 4-00 is increased somewhat by a reduction in the resistance of the supervisory circuit described above. This resistance reduction is effected by the exclusion-from the supervisory .deenergized and the fire clock mechanism is released to transmit four rounds of the alarm signal from contacts 1-08 actuated by the from code wheel 1-05 of the fire clock 1-00.

The trouble clock release magnet 2-03 remains energized because the trouble relay 4-00 remains operated, as previously described, and its contacts 4-02, 4-03 which control the release magnet winding 2-04 remain closed. The code wheel actuated contacts 2-08 of the trouble clock 2-00 which are in series with the active fire clock code wheel contacts 1-09 therefore remain inactive and closed so that there is no interference by the trouble clock 2-00 with the transmission of the fire signal by the fire clock l-00. After the transmission of four rounds ofthe fire signal has been completed by the fire-clock 1-00, detent mechanism (not shown) cooperating with the notch 1-14 in the wheel 1-15 prevents further operation of the fire clock 1-00. During this transmission of the four rounds of the fire signal by the code wheel 1-05 of the fire clock 1-00, the auxiliary contacts 1-12 and 1-13 are held closed. These contacts are normally open and are closed by the cam 1-11 only during the actual transmission of the four rounds of fire signal. Before and after the transmission of the four rounds of the fire signal, the contacts 1-12 and 1-13 are open. The Local contacts 1-12 are usually connected to operate a locking relay (not shown) controlling a warning bell located in the building engineers ofiice or at some other normally attended place in the protected premises. The Shunt" contacts 1-13 are used to shunt out other transmitters on the same central otfice circuit.

After the fire condition has been cleared and the system is restored to normal, re-energization of the fire clock release magnet 1-03 causes the fire clock to transmit a single round of the fire signal, this being effected by the detent mechanismwhich cooperates with the notched wheel 1-15 on the cam shaft 1-10. Because of the 5:1 ratio between the speeds of the code wheel shaft 1-07 and the cam shaft 1-10, the transmission of the single round of the fire signal following the four rounds brings the cam shaft 1-10 and the cam 1-11 to the initial or starting position. The single round also informs the operator at the central ofiice that the transmitter has been restored to normal and that it is back in service, ready to transmit another fire signal.

Open circuit trouble condition Assume, for example, that there has been a break in one of the house loop conductors 45 or 46. This break opens the closed supervisory circuit described above in connection with the trouble relay 4-00 and deenergizes the operating winding 4-01 of the trouble relay. At the same time, the operating winding 3-01 of the alarm relay is also decnergized because this winding is likewise included in the supervisory circuit. The broken circuit condition thus releases both the alarm relay 3-00 and the trouble relay 4-00 simultaneously.

Release of the alarm relay 3-00 causes it to open its contacts 3-02 thereby interrupting the supply of current to the fire clock release magnet winding 1-04. However, release of the trouble relay causes closure of trouble relay contacts 4-02 and 4-04. Closure of trouble relay contacts 4-02 and 4-04 energizes the fire clock release magnet winding 1-04 through an alternate circuit extending from panel terminal 8 through trouble relay contacts 4-02, 4-04, a conductor 32, the normally closed trouble clock run-down contacts 2-14 and rectifier 44. The capacitor 36 is thus maintained fully charged and the fire cloc'k release magnet 1-03 remains energized notwithstanding release of the alarm relay 3-00.

Release of the trouble relay 3-00 causes it to open its contacts 4-02, 4-03 which are normally closed and thus deenergize the trouble clock release magnet winding 2-04. The trouble clock 2-00 thereupon operates to transmit a single round of the trouble signal by means of its code wheel actuated contacts 2-08. As previously noted, the fire clock release magnet winding is held energized by release of the trouble relay 4-00 so that code wheel actuated contacts 1-08 of the fire clock remain inactive. Since the code wheel actuated contacts 1-08 of the fire clock and 2-08 of the trouble clock are connected inseries with each other, it is essential that one set of contacts shall remain inactive and closed while the other set of contacts is in operation.

After the single round of the trouble signal has been transmitted, the arm 2-10 of the trouble clock opens the normally closed trouble clock run-down contacts 2-13 and '2-14 and closes the normally open contacts 2-11 and 2-12. This actuation of the run-down contacts transfers the circuit from the normal condition shown in Fig. 2 to the trouble condition shown in Fig. 3. In Fig. 3, the circuit through the tamper switch 20 and panel terminal 2 has been omitted for simplicity of illustration, panel terminal 1 being shown connected directly to panel terminal 3.

With the circuit rearranged by operation of the rundown contacts 2-11 to 2-14, the normal ground connection to the negative side of the current supply at terminal 7 is broken by contacts 2-13. The system is thus converted to a system with an ungrounded power supply.

Both ends of the house loop conductor 45 are connected together by run-down contacts 2-11. Both ends of the other house loop conductor 46 are connected together by run-down contacts 2-12. With single break in either or both of the house loop conductors 45 and 46, the contacts of the alarm signal device 47 will nevertheless be connected to panel terminals 3 and 4, either directly or through panel terminals 5 and 6 and the closed run-down contacts 2-12, 2-11 of the trouble clock 2-00. The other set of run-down contacts 2-14 disconnects the circuit of the fire clock release magnet winding 1-04 from trouble relay contact 4-04 so that the winding 1-04 is entirely independent of the condition of trouble relay 4-00. The fire clock release magnet winding 1-04 will thus be continuously energized so long as the alarm relay 3-00 is operated. The trouble relay 4-00 is no longer needed because the trouble clock 2-00 has already transmitted the trouble signal to the central ofice and has actuated its run-down contacts to set up the trouble circuit condition shown in Fig. 3.

. Assuming the broken connection to be in house conductor 46 as indicated at 41 in the trouble circuit condition, there is established a closed circuit from the positive panel terminal 8 through run-down contacts 2-11, winding 3-01 of alarm relay 3-00, resistor 29, run-down contacts 2-12 and the winding 4-01 of trouble relay 4-00 to the negative panel terminal 7. Although the alarm device 47 is disconnected from panel terminal 3 by the break in house loop conductor 46 at 49, the alarm device 47 still remains connected to panel terminal 8 through the unbroken portion of the house loop conductor 46. Panel terminal 8 is in turn connected to panel terminal 3 through the closed run-down contacts 2-12. When the contacts of the alarm device 47 close, the winding 3-01 of the alarm relay 3-00 will be shunted and the alarm relay 3-00 will thereupon release. Release of the alarm relay 3-00 causes transmission of a tire signal by the fire clock 1-00 in the same manner as that described above for normal circuit conditions of the house loop conductors.

Grounded circuit trouble condition As previously described, one end of the winding 4-01 of trouble relay 4-00 is connected substantially directly to the negative panel terminal 7. The other end of the winding 4-02 is connected to the positive panel terminal 8 over a supervisory circuit which includes both of the house loop conductors 45 and 46 connected in series. Negative panel terminal 7 is normally grounded through rundown contacts 2-13 of the trouble clock 2-00. As a result, a ground on either of the loop conductors 45 or 46 will shunt the winding 4-01 of trouble relay 4-00 by causing both ends of the winding to be grounded, one

end being grounded through run-down contacts 2-13 and the other through the circuit fault.

If the ground is on house loop conductor 45, both the alarm relay winding 3-01 and the trouble relay winding 4-01 will be shunted out. Excessive current flow will be prevented by the current limiting resistor 28. Both the alarm relay 3-00 and the trouble relay 4-00 will be released simultaneously and the trouble signal will be transmitted as described above. After transmission of the trouble signal has been completed trouble circuit conditions will be established as described above and as shown in Fig. 3.

In the trouble circuit condition of Fig. 3, the ground circuit connection from panel terminals 9 and 10 to negative panel terminal 7 is broken at the run-down contacts 2-13. The supply is ungrounded. So long as there is a ground fault only on a single one of the house loop conductors 45 and 46, the fault will have no eliect because it is the only ground connection to the system, the normal ground connection having been broken by run-down contacts 2-13 of the trouble clock. Operation of the system with the ground fault will therefore be the same as that described above for the open circuit trouble condition. This will be apparent from Fig. 3, assuming a ground fault to be present at 54. Because the normal ground connection has been broken by the trouble clock run-down contacts 2-13, the only ground on the system consists of the ground fault indicated at 54 which will have no effect on the operation of the system since the system is otherwise ungrounded.

Change of retard interval As previously described, it has been assumed that there will be a 30 second delay between the opening of contacts 3-02 of the alarm relay 3-00 and the tripping of the release magnet 1-03 of the fire clock 1-00 to initiate the four rounds of fire signal. Such a delay interval is appropriate for a water flow alarm in an automatic sprinkler system.

In an aero system, in which a sudden rise in temperature caused by a fire produces an abrupt increase in air pressure in pneumatic tubing extending throughout the protected area, a 30 second delay is not required. The 30 second delay, which is necessary to avoid water hammer efiects may be considerably shortened in an aero system. For this purpose, a resistor 50 is provided which may be connected in multiple with the capacitor 36 so that its discharge time is shortened accordingly. A delay interval of 12 seconds is suitable in the case of an aero system.

As shown in Pig. 2, one terminal of the resistor 50 is connected to a terminal screw 41 on the panel 10. The positive terminal of the electrolytic capacitor 36 is connected to a terminal screw 42 on the panel 18. The other terminal of the resistor 50 and the negative terminal of the capacitor 3e are both connected to the negative supply conductor 25. When terminal screws 41 and 42 are connected together, the resistor is connected directly multiple with the capacitor so that its discharge time with reference to the fire clock release magnet 1-03 is reduced from 30 seconds to 12 seconds.

When the 30 second delay is used, a nameplate 40 of insulating material (Fig. 4) is mounted on the termirial screws 41 and 42. As shown in Fig. 1, the insulating nameplate '40 bears the legend Waterflow Flow Transmitter-Long Retard. This indicates to a user of the transmitter that it is arranged for operation with an automatic sprinkler system. In this case the resistor 50 is disconnected. In the case of an aero system, a metal nameplate 43 is mounted on the terminal screws 41 and 42, as shown in Fig. 5. The metal nameplate 43 bears a suitable legend (not shown) indicating that the transmitter is arranged to provide a short retard interval. Being made of metal, the nameplate 43 establishes an electrical connection between the terminal screws 41 and 42 and thus connects the resistor 50 in multiple with the capacitor 36 to reduce its discharge time.

Operation of the tamper switch As previously described, the tamper switch has 'a closed circuit position in which it is held by the door of the cabinet in which the transmitter is enclosed while the cabinet door remains closed. If the cabinet door is opened, the supervisory circuit is broken by the tamper switch 20 and the trouble clock transmits a trouble signal in the usual manner. If the cabinet door has been opened by some unauthorized person, the operator at the central ofiice will dispatch repair personnel to the protected premises. If however, the door is opened for purposes of inspection and maintenance, the inspector will operate the tamper switch manually to another closed position in which it will remain closed while the cabinet door is open. This recloses the supervisory circuit for purposes of routine testing and inspection.

, After the testing and inspection have been completed, the trouble clock is fully wound by the application of a key to its winding stem 2-01 so that the run-down contacts 2-11 to 2-14 are brought to their respective normal conditions. In thecase of an intermittent ground or break, the cam 206 is advanced step by step until contacts 208 ride up on the face of cam 206 and remain open throughout the duration of the trouble signal, closing at the end of this signal so that the mechanism can be rewound.

When the trouble'clock is operated to transmit a trouble signal, the contacts 2-09 open again making the release magnet 2-03 independent of the condition of the trouble relay 4-00. In this manner, an intermittent trouble condition which will operate and release the trouble relay 4-00 cannot interfere with the transmission of the trouble signal by intermittently energizing the trouble clock release magnet winding 2-04 during transmission of the trouble signal. The cam actuated contacts 2-09 thus insure that a trouble condition of short duration cannot stop the trouble clock with its contacts 2-08 actuated by a code wheel tooth so that the central olfice circuit is left open or grounded.

In the case of the shunt contacts 27 at the right in Fig, 2, it is desirous to remove the shunt as soon as the four rounds are completed and the clock is stopped, so that any other transmitter protecting another part of the building will not be inoperative while the first transmitter remains in the fire signal condition.

While the clock mechanisms have been referred to as fire and trouble clocks, it will be appreciated that this is for identification rather than forlimiting purposes, and this is true of other terms employed herein. The fire clock may be considered an alarm transmitting unit and the trouble clock a unit for detecting faults such as breaks or grounds in the transmitting circuits and for curing or eliminating those faults to keep the fire clock in alarm transmitting condition .The transmitter as a whole has been designed to work in with any of the accepted and more or less standard fire protection'systems and for that reason is operative on the McCullogh circuit and utilizes, where possible, conventional proven parts such as a Spies recycling cam on the fire clock and the like.

Being completely automatic and self-supervising, this transmitter is particularly suited to the protection of present-day establishments which, as a general rule, are closed and left unattended over the week-end periods from Friday to Monday.

The resistor 31 in series with the capacitor 36 prevents the sending in of a false alarm if the capacitor for any reason should short circuit, and this also prevents injury or destruction of contacts 3-02 in the event of a capacitor short circuit.

The insulating cam 2-06 on the trouble mechanism makes it possible to close the door with any type tamper switch such as now in use and prevents an intermittent trouble, such as a break or ground, from leaving the central office circuit open or grounded if the clock should stop with the central oifice springs on a tooth of the signal wheel 2-05.

The power failure current relay 5-00 by transferring the central office wires 24 to a distinct current failure signal wheel 1-06 on the fire clock 1-00, makes it unnecessary to put a retard on the trouble clock. The insulating cam 1-11 on the fire clock enables the engineer in charge to shut off local signal bells any time after completion of a four-round fire signal and the shunt contacts 1-13 open at the end of four rounds of fire signal, so that any other transmitter in the same building can send in signals to the central office.

The fundamental circuit, as indicated in Fig. 3, will detect a ground on either leg of the house loop, as distinct from prior transmitters which only detect grounds on first one leg, condition the circuit and then detect 0 the other leg.

What is claimed is:

1. An alarm system comprising a spring driven fire clock having a release magnet, said fire clock being operative to transmit a fire signal upon deenergization of its release magnet; a spring driven trouble clock having a release magnet, said trouble clock being operative to transmit a trouble signal upon deenergization of its release magnet; a source of current; an alarm relay having an operating winding and contacts connecting said fire clock release magnet for energization from said source when said alarm relay winding is energized; a trouble relay having an operating winding and contacts connecting said trouble clock release magnet for energization from said source when said trouble relay winding is energized; a closed supervisory circuit energized from said source and including both of said relay operating windings connected in series; further contacts on said trouble relay connected to energize said fire clock release magnet independently of said alarm relay contacts when said trouble relay winding is deenergized; and an alarm signal device connected to said supervisory circuit, said alarm device having contacts connected to shunt out said alarm relay winding while maintaining current flow in said supervisory circuit for causing transmission of said fire signal, whereby closure of said alarm device contacts will operate said fire clock independently of said trouble clock and an open circuit condition in said supervisory circuit will operate said trouble clock independently of said fire clock.

2. An alarm system according to claim 1, further comprising a panel on which said clocks and said relays are mounted, said supervisory circuit extending exteriorly of said panel as a two-wire circuit to said alarm device contacts and back to said alarm relay winding, said trouble clock further comprising run-down contacts actuated after operation of said trouble clock to transmit a trouble signal, said run-down contacts separately connecting each end of said alarm relay winding to both ends of one of the wires of said two-wire circuit, whereby said alarm relay winding may be shunted by said alarm device contacts notwithstanding a break in said two-wire circuit.

3. An alarm system according to claim 2, in which said source is ungrounded, said system further comprising ad- :ditional run-down contacts actuated along with said first named run-down contacts, and a ground connection extending through said additional run-down contacts to the side of said source which is electrically nearer said trouble relay winding than to said alarm relay winding, whereby .said trouble relay winding will be shunted in the event of a ground fault on said two-wire circuit, said additional contacts opening after transmission of said trouble signal so that the only ground on said supervisory circuit is said ground fault.

4. An alarm system according to claim 1, further comprising a current failure relay having a winding connected to said source, one of said clocks having circuit means oeprative during the running of said one clock for transmitting a distinctive current failure signal, said current failure relay comprising contacts actuated upon deenergrzation of its Winding to render said circut means operative to transmit said distinctive signal and to render -both of said clocks simultaneously inoperative to transmit either of their normal sginals.

5. An alarm system according to claim 1, further comprising a capacitor connected to said fire clock release magnet for prolonging its energization when it would otherwise be deenergized, whereby said alarm device contacts must be closed for a predetermined minimum time =contacts, deenergization of said trouble clock winding causing the transmission of a trouble signal over said central ofiice circuit; a source of current; an alarm relay having an operating winding and contacts which connect said fire clock winding for energization from said source when said alarm relay is operated; a trouble relay having an operating winding and contacts which connect said trouble clock Winding for energization from said .source when said trouble relay is operated; a closed supervisory circuit continuously energized from said source, both of said relay operating windings being serially. included in said supervisory circuit in series with each other for maintaining said relays operated; an alarm device having contacts connected to said supervisory circuit for separately shuntin said alarm relay winding to release said alarm relay independently of said trouble relay winding; and further contacts on said trouble relay connected to energize said fire clock windin independently of said alairn relay contacts when said trouble relay is released, whereby closure of said alarm device contacts will cause transmission of a fire signal independently of said trouble signal and a break in said supervisory circuit will cause transmission of said trouble signal independently of. said lire signal.

7, An alarm system according to claim 6, further comprising a panel upon which said clocks and said relays are mounted, said supervisory circuit extending as a twowire circuit from said panel to said alarm device contacts and back to said alarm relay operating winding; and run-down contacts included in said trouble clock, said run-down contacts being operative after transmission of said trouble signal separately to connect the opposite ends of each wire of said two-wire circuit together, whereby said supervisory circuit is closed notwithstanding a break in said two-wire circuit and said alarm device contacts are connected to shunt said alarm relay winding notwithstanding said circuit break.

8. A11 alarm system according toclaim 6, wherein said source is ungrounded, one terminal of said source being connected substantially directly to one side of said trouble relay winding, the other terminal of said source being connected to said source through said supervisory circuit, said system further comprising normally closed run-down contacts in said trouble clock, said run-down contacts opening after transmission of said trouble signal, and a ground connection extending to said other terminal of-said source through said run-down contacts, whereby a ground fault on said supervisory circuit will shunt said trouble relay winding thereby causing said trouble clock to transmit a trouble signal, whereafter said rundown contacts will open leaving said ground fault as the only remaining ground connection to said supervisory circuit.

9. An alarm system according to claim 6, in which said source supplies direct current, said system further comprising a capacitor connected in parallel with said fire clock release magnet winding for prolonging the energization thereof, whereby said alarm device contacts must remain closed for a predetermined minimum time interval before said fire clock will transmit said first signal.

10. An alarm system according to claim 9, wherein said capacitor is an electrolytic capacitor, said system further comprising a rectifier connected in series with the parallel combination of said fire clock winding and said capacitor, said rectifier being so poled that said fire clock winding can be energized only when the polarity of said source is correct with respect to the polarity of said electrolytic capacitor.

11. An alarm system according to claim 9, further comprising additional code wheel actuated contacts in said fire clock for transmitting a distinctive current failure signal; a current failure relay having a winding connected to said source, said current relay having contacts effective upon deenergization of its Winding to disconect said firstnamed code wheel actuated contacts from said central ofiice circuit and to substitute said additional code wheel actuated contacts therefor, said current relay having further contacts connected in series with said fire clock winding for completely deenergizingsaid fire clock winding independently of said capacitor and said alarm and trouble relay contacts immediately upon deencrgization of said current relay winding.

12. In an alarm transmitter having a fire clock and a trouble clock; a release magnet for each clock, deenergization of either of said release magnets initiating operation by its associated clock; code wheel actuated contacts included in each clock for the transmission of respective fire and trouble signals thereby; further code wheel actuated contacts included in one of said clocks for transmitting a distinctive current failure signal during operation thereof; an energizing circuit adapted for connection to a current source for normally continuously energizing both of said release, magnets; a current failure relay having an operating winding connected to said energizing circuit; and contacts included in said relay and responsive to failure of said current source for rendering said firstnamed code wheel actuated contacts inoperative and said further code wheel actuated contacts operative.

References Cited in the file of this patent UNITED STATES PATENTS 2,032,092 Johnson et al. Feb. 25, 1936 2,122,222 Vingerhoets June 28, 1938 2,530,749 Yardeny Nov. 21, 1950 2,594,069 Poehlmann Apr. 22, 1952 2,699,541 Ward Jan. 11, 1955

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