US2149200A - Alarm signal system - Google Patents

Description

Feb. 28, 1939. J, H. w oc ET AL 2,149,200

ALARM SIGNAL SYSTEM Filed June 4, 1954 4 Sheets-Sheet 1 SoLsr-wm 85145 THERMAL f3 OPERA-roe Feb. 28, 1939. w oc ET AL 2,149,200

ALARM SIGNAL SYSTEM Filed June 4, 1934 4 Sheets-Sheet 2 THERMAL OPERATOR Jig. z

Feb. 28, 1939. J. H. WHEELOCK ET AL 2,149,200

ALARM SIGNAL SYSTEM Filed June 4, 1954 4 Shets-Sheet s Feb, 28, 1939.

J. H. WHEELOCK ET AL ALARM SIGNAL SYSTEM Filed June 4, 1934 4 Sheets-Sheet 4 8 f ail THERMAL OPERHTOR g SOLENOID BELL imam/5m.

Jim HifizeeZac/r fia /f JCkG/Ma Patented Feb. 28, 1939 UNITED STATES PATENT OFFICE ALARM SIGNAL SYSTEM Application June 4, 1934, Serial No. 728,812

8 Claims.

The present invention relates to alarm signal systems, particularly fire alarm systems, employing a number of bells, or other signals, adapted to be sounded, or otherwise operated, in response to the actuation of any one of a number of separate alarm sending stations, such alarm systems being commonly installed in schools, factories, hotels and other large buildings.

In the installation and operation of alarm signal systems, particularly fire alarm systems, certain essential conditions should be met, such as continuous electrical supervision of the various circuits of the system, so that any accidental breaks or grounds in the circuits under control 5 or interruptions to the power supply will immediately be called to attention by the operation of a special trouble signal, distinct from the alarm signals. Furthermore, it is most desirable that the alarm signals should not be sounded upon the occurrence of any of the abnormal conditions mentioned above.

According to the present invention, there is provided an improved alarm signal system characterized by its ability to automatically indicate the occurrence of any abnormal circuit condition without operating the alarm signals, so as to give a false alarm. Furthermore, the system is characterized by the utilization of a single master controller winding, thereby enhancing its simplicity and reliability in operation, and materially reducing the cost of installation and of maintenance. The above and other advantageous features of the invention will hereinafter more fully appear from the following description with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view illustrating the system in its normal inoperative condition, with continuous electrical supervision of the various circuits.

Fig. 2 is a schematic view similar to Fig. l, illustrating the circuit relations established upon operating one of the alarm sending stations.

Fig. 3 is a schematic View illustrating the sending of the first impulse of an alarm.

Fig. 4 is a view in front elevation, showing the construction of a master circuit controlling device embodied in the system.

Fig. 5 is a view in end elevation of the device shown in Fig. 4.

Fig. 6 is a schematic view, illustrating a modification of the system.

Figs. 7 and 8 are schematic views, similar to Fig. 1, illustrating the invention embodied in a pre-signal and general alarm system.

ing an operating winding 2.

Like reference characters refer to like parts in the different figures.

Referring first to Fig. 1, the signals I which are adapted to be sounded, or otherwise electrically operated in the system, for giving an alarm are 5 shown, for purposes of illustration, as being of the single-stroke solenoid type with each provid- The windings 2 of the signals I are adapted to be connected in sections across the supply mains 3 and 4, with bal- 0 ancing resistors 5 therebetween, by means of a number of pairs of relatively movable contacts 6 and 6a, 1 and 1a, with such contacts forming part of a master controller generally indicated by the reference character A.

Referring to Figs. 4 and 5, the master controller A comprises a U-shaped magnetic core 8, one leg of which is surrounded by an energizing winding 9, while the lower end of the other core leg supports a main armature l0 and an auxiliary arma- 20 ture ll movable independently of the main armature on a common pivot. The main armature l0 carries a bar I 2 on which are mounted, in pairs,

a number of contacts 6 and 1 corresponding to the movable contacts of the several sets of contacts 25 shown in Fig. 1 for controlling energization of the signal windings 2. These contact arms 6 and 1 are insulated from the bar 12 at IZa and cooperate with stationary contacts 6a and la mounted on an insulating base 13 carrying the master con- 30 troller A. Therefore, closure of the main armature ID, in response to energization of the winding 9, is adapted to simultaneously energize the signal windings 2 in sections according to the connection of the several stationary contacts 6a to 35 the signal windings 2 and the connection of the other contacts la to the supply mains 3 and 4.

Referring again to Fig. 1, the winding 9 of the master controller A is shown as having one terminal permanently connected to the supply main 3 40 through an ammeter I4, while the other terminal thereof is connected in series with a number of alarm sending stations l5, 15 disposed at various locations throughout the system from where it is desired to send an alarm. The stations 15 are 45 also in circuit with the several signal windings 2, with a condenser 16 interposed between the stations [5 and the winding 9 when the supply mains are energized by alternating current. Each sending station 15 provides a pair of relatively mov- 5o able contacts Ha and Nb, normally closed, so long as the station is in an inoperative condition and, for purposes of illustration, each station [5' is shown as comprising a contact actuating member l8 in the form of a cam wheel normally sta- 55 tionary. The function of the cam wheel l8, when rotated, is to open and close the contacts Ha and lib to successively interrupt and re-establish the circuit through the stations l5.

Since many different types of sending stations are employed in fire alarm systems, it is unnecessary to further describe the structural details of each station l5, other than to say that normally the position of the cam wheel I8 is such as to maintain the station contacts Ila and I'll) closed while the station is in its inoperative condition. Then, upon operation of the station for the purpose of sending an alarm, rotation of the cam wheel I8 momentarily separates the contacts Ho. and llb, whereupon engagement of the contacts is re-established, in accordance with the arrangement of the cam projections on the wheel IB. In other words, operation of a sending station l5 results in alternately breaking and remaking the circuit through the station contacts Ila and 11b, and obviously the cam wheel l8 can be driven through suitable operating mechanism, not shown, so as to send a number of signal impulses through the system for operating the signal windings 2 in accordance with a code, as will be hereinafter described.

With the parts of the system in the condition shown in Fig. 1, that is the normal condition in which the system is prepared to send signals, a continuous circuit is maintained from the lower terminal of the winding 9 through the closed contacts Ila and Nb of the several stations IS in series, and from thence to the other supply main t through the windings 2 of the signals I, also in series. Beyond the windings 2 the circuit to the supply main 4 also includes a resistor 19, and the normally closed contacts 20 and 2| of a time delay cut-out device comprising an operating winding 22 in circuit with one of the contacts 20. In passing to the winding 22 the current traverses the thermal element 23 of an automatic interrupter, the function of which will hereinafter appear.

The circuit interrupter of which the thermal element 23 forms a part, comprises a pair of normally closed contacts 240. and 2412, which are connected in circuit with a resistor 25 between the main 3 and the lower terminal of winding 9, so as to constitute a shunt around the controller winding. The existence of this shunt circuit permits the flow of only a small supervisory current through the winding 9 of the master controller A, as indicated by the small arrows in Fig. 1, which current also traverses the stations l5 and the signal windings 2. As a result, the winding 9 of the master controller is not energized sufficiently to pull up the main armature l0, so that the several pairs of contacts 6 and 6a and 1, la which control the energization of the signal windings 2 remain in an open condition.

The strength of the supervisory current flowing through the winding 9 of the master controller A is sufficient, however, to hold up the auxiliary armature II, as shown in Fig. 5, and this armature l l serves for a number of purposes which will next be described. The free end of the auxiliary armature l l carries a rod 26 extending upwardly in front of the winding 9, and with the armature held up by the supervisory current, an insulating plate 26a at the upper end of the rod is held just clear of a resilient contact 21 that is normally spaced from a second stationary contact 28. The contact 2'! is connected to the supply main 3, while the other contact 23 is connected to one terminal of the winding 29 of a trouble signal 30, such as a bell, with the other terminal of the winding 29 connected to a third supply main 4a. Thus, the circuit of the operating winding 29 of the trouble signal 33 is maintained in an open condition so long as the auxiliary armature l l is held up by the fiow of supervisory current through the winding 9 of the master controller A, and this is the state of affairs illustrated in Fig. 1. Obviously, any interruption in the flow of supervisory current such as would be caused by an accidental break, or ground, in the sending station or signal circuits, immediately results in the dropping back of the auxiliary armature H, whereupon the pressure exerted by the insulating plate 2611 at the top of the rod 26 closes the contacts 2! and 2B and energizes the winding 29 of the trouble signal.

As long as any abnormal condition in the system exists which prevents flow of supervisory current, as indicated in Fig. 1, the trouble signal 30 will sound continuously to call attention to the fact that the system is in an inoperative condition. Power is then removed from the system by deenergizing the supply mains 3, 4 and do before mending the break in the system, or clearing the ground, as the case may be, so that upon resumption of power only the flow of supervisory current through the winding 9 will be resumed. Thereupon the auxiliary armature II will move upwardly to the position of Fig. 5 to disconnect the trouble signal 36, without operating the signals l As best shown in Fig. 4, the rod 26, in addition to controlling the contacts 21 and 28, is also adapted to control additional pairs of contacts 3!, 32 and 33, 33. These pairs of contacts are similar in construction to the contacts 21 and 28, so that they remain separated so long as the attraction of the auxiliary armature H by supervisory current holds the rod 26 up. Upon downward movement of the rod, however, the insulating plate 26a causes all three upper contacts 21, 3! and 33 to engage the lower contacts 28, 32 and 34 respectively.

Referring again to Fig. 1, it will be seen that the contact 3| is connected directly to the supply main 3, while the contact 32 is connected to the signal circuit between the resistor 19 and the thermal element 23in series with the movable contact 2| of the time delay device. The other movable contact 33 is connected to the supply main 4 through the resistor 35, with the stationary contact 34 of this pair connected in the signal circuit between the resistor 19 and the balancing resistor 5 of the last section of signal windings 2. Consequently, when the small armature ll drops, two things happen in addition to the energization of the trouble signal 30,namely, the establishment of a circuit directly from the main 3 through thermal element 23 and winding 22 to main 4, independently of the master controller winding 3, and the establishment of a circult from the main 4 to the terminal of the signal winding circuit farthest removed from the controller winding 9, independently of the winding 22 and thermal element 23.

Let it now be assumed that one of the stations I5 is operated for the purpose of giving an alarm by the system, thereby momentarily opening a pair of station contacts Ila and Nb, as indicated in Fig. 2. When this occurs, the flow of supervisory current through the winding 9 is interrupted, whereupon the auxiliary armature l l drops back as indicated, to cause engagement of the several contacts 21, 3| and 33 with the cooperating contacts 28, 32 and 34 respectively. In Fig. 2 such engagement between the contacts is indicated by showing bridging members movable with the auxiliary armature I. This action operates the trouble signal 39, and in addition causes an increased current to flow through the thermal element 23 and winding 22 through the then closed contacts 3| and 32. One end of the thermal element 23 is anchored, while its other end is connected to a pivotally mounted arm 36, and at ordinary room temperature the tension of the thermal element 23 maintains an insulated tip 36b at the free end of this arm 36 below the end of the upper contact 24a in the circuit of the shunt resistor 25. As the increased current flows through the thermal element 23, it expands and a spring 36a acting on the arm 36 swings the end of the arm upwardly until it lifts contact 24a out of engagement with contact 2419. The thermal element 23 is so adjusted that the arm 36 separates the contacts 24a and 24b almost immediately after the small armature I drops upon breaking of the box circuit, so that the shunt resistor 25 is removed from the lower terminal of the master controller winding 9 before the station contacts Ila and Ill) are reclosed by rotation of the cam wheel |8 in response to operation of the station, as indicated in Fig. 3.

Upon re-closure of the box contacts Ila and Ho following the operation of a sending station IS, an increased current flows through the master controller winding 9, due to the removal of the shunt resistor 25 and the previous closure of contacts 33 and 34 which has established a direct circuit to the supply main 4 from the last signal circuit resistor 5. The main armature In thereupon pulls up as shown in Fig. 3, to close the several pairs of master controller contacts 6, 6a and I, la to simultaneously energize the windings 2 of all of the signals I. This gives the first signal impulse of the code, as determined by the projection IS on cam wheel l8 of the station l5 which has been operated. While the closure of the main armature I9 is accompanied by closure of the auxiliary armature II, the opening of the contacts 33 and 34 as the auxiliary armature reaches its upper position does not interrupt the circuit of the master controller winding 9, owing to the fact that previous closure of the upper pair of master controller contacts 6, 6a and 1, la establishes a holding circuit for the controller winding 9 direct to the supply main 4. Furthermore, opening of contacts 3| and 32 does not afiect the open circuit of shunt resistor 25, since the element 23 has only partly cooled and contacts 24a and 24b are still open, see Fig. 3.

Continued rotation of the cam wheel l8 following the sending of the first signal impulse results in separation of the station contacts Na and Nb, whereupon both armatures I6 and H drop to open the signal energizing contacts and reclose the several pairs of contacts under the cpntrol of the rod 26. In this interval between the first and second signal impulses, during which the master controller winding 9 is entirely deenergized, the re-closure of contacts 3| and 32 again sends current through the thermal element 23, thereby again heating the element Y23 and preventing its continued contraction from permitting the arm 36 to re-close the shunt controlling contacts 24a and 2419". Therefore, upon re-closure of the station contacts l'lu. and Ho by projection l8", the shunt resistor 25 is still out of circuit and a relatively heavy current flows through the main controller winding 9 to again energize all the signal windings 2 and send the second signal impulse. Since the cam. wheel l8 shown in the first sending station l5 provides only two cam projections l8 and I8", in addition to the holding projection |8, continued rotation of the cam wheel to close contacts Fla and I'll) by the projection |8, results in the sounding of only one more signal sequence impulse to complete sending of the signal three.

Following sending of the signals by the station which has been operated in the manner described above, the station contacts Ila and I'll) are held closed by the projection |8 until the cam wheel it! comes to rest after one or more complete revolutions with the projection H3 in the same angular position as at the start, as indicated in Fig. 1. This final re-olosure of the station contacts by projection |8 pulls up both armatures I0 and H and the resulting cooling of element 23 causes closure of contacts 24a and 24b to reconnect the shunt resistor 25 across the terminals of the controller winding 9. This action occurs only after the contacts 3| and 32 have been opened an appreciable time by the lifting of the rod 26, cooling and contraction of the thermal element 23 serving to swing the arm 36 downwardly to permit the contact 24a to reengage the contact 24b. Upon this restoration of the circuit of the shunting resistor 25, the current fiowing through the winding 9 is reduced to such a value that the main armature l9 falls, while the supervisory current continues to flow through the winding and maintain the system in the condition shown in Fig. l, preparatory to sending another alarm upon operation of any one of the sending stations I5.

As previously pointed out, it is one of the principal objects of the present invention to provide an alarm system in which the alarm signals will not be operated upon the occurrence of any abnormal circuit condition, so as to sound a false alarm, the invention contemplating the operation of only the trouble signal 39 upon the occurrence of any such condition. For example, should a ground occur in any of the sending stations or in any of the signal circuits, this will have the effect of cutting out the winding 9, since one terminal thereof is grounded through the supply main 3. Furthermore, the resistor I9 between the ungrounded main 4 and the signals I, will prevent operation of the signals from a ground in any signal circuit. The resulting interruption of the supervisory current through the winding causes the auxiliary armature H to drop thereby operating the trouble signal 39 through closure of the contacts 2! and 28. As previously pointed out, dropping of the armature II also closes contacts 3| and 32, thereby throwing both the winding 22' and the thermal element 23 across the mains 3 and 4, see Fig. 2.

Assuming that the ground is maintained for any appreciable length of time, the resulting opening of the shunt resistor contacts 24a and. 2327 due to expansion of the thermal element 23 will have no effect since winding 9 is grounded out. Furthermore, a sustained ground is followed by functioning of the time delay device to automatically open the contacts 29 and 2|. One way of accomplishing this result is by causing the heat generated in the winding 22 which is of relatively low resistance to be conveyed to a bithermal latch member 22a normally holding the contacts 20 and 2| closed, which member 22a upon fiexure due to unequal expansion unlatches the contact 2|. This separation of contacts 29 and 2| immediately deenergizes the thermal element 23, and its resulting contraction permits reclosure of contacts 24a and 24b to maintain the resistor 25 shunted across the terminals of winding 9.

Therefore, upon clearing of the ground following indication thereof by the sounding of the trouble signal 30, the alarm signals will not be sounded to give a false alarm upon re-closure of the contacts 253 and 2| manually. In fact, until the contacts 20 and 2! are re-closed following release of the contact 2! by the latch member 22a, the trouble signal will continue to sound to indicate that the system is still in an inoperative condition. Consequently, re-closure of the contacts 2t and 2% has only the effect of restoring the flow of supervisory current through the winding 9 to pull up the small armature H and disconnect the trouble signal 30.

Similarly, upon the occurrence of an open circuit in the system, as by breakage of a wire in any of the sending stations or signal circuits, dropping of the small armature II will immediately sound the trouble signal 39. This trouble indication is also followed, after a predetermined interval, by automatic operation of the bi-thermal latch member 22a to disconnect the thermal element 23 from the supply main 3 in the manner previously described, so that upon repair of the open circuit, the alarm signals will not be sounded upon re-closure of the contacts 20 and 2|. Therefore, the net result of the occurrence of any abnormal condition in the system, such as a ground or open circLL't, is the energization of the trouble signal 3!), which of course may be either audible or visual or both, and is operated without any possibility of the alarm signals being sounded prematurely, either upon occurrence of the abnormal circuit condition or upon remedying the same.

Upon any interruption of the power source supplying the mains 3 and 4, obviously both relay armatures Ill and II will fall, but closure of the contacts 3| and 32 has no effect on the thermal element 23, since the power main 3 then is dead. Therefore, upon resumption of the power supplied to the mains 3 and 4, only the small armature II will pull up in response to flow of supervisory current, since the shunt resistor 25 has remained across the terminals of the winding 9 during the period of power interruption. Therefore, there will be no premature ringing of the alarm signals to give a false alarm, as a result of any interruption and subsequent resumption of the power source.

Referring now to Fig. 6, there is shown a modification of the system wherein the circuits are simplified, although the modified arrangement does not display quite the same supervision and responsiveness to abnormal circuit conditions, as compared to the arrangement of Fig. 1. In the modified arrangement, like reference characters are applied to the same elements that have been previously described with reference to Fig. l, and the principal difference between the arrangements of Fig. 6 and Fig. 1 resides in connecting the sending stations l5 across the terminals of the main controller winding 9. A shunt resistor 31 of lower value than the resistance of winding {2 is connected in series with the sending stations !5, so that the current passing through the winding 9 is reduced to a low value, and only the small armature I l is held up. As a result, the several alarm signal circuits including the windings 2 are supervised, so that any break or ground in these circuits causes the armature l! to drop and energize the trouble signal 38 through closure of contacts 2'! and 28.

Upon operation of a sending station l5, the initial separation of the station contacts Ila and I'll) removes the effect of the shunt resistor 3'! from the controller winding 9, so that the increased current flowing through the winding 9 pulls up the main armature In. This results in the sending of a signal impulse through the system upon energization of the signal windings 2. Continued rotation of the cam wheel l8 of the station l5 which has been operated causes reclosure of the contacts Ila and !lb, thereby restoring the shunt circuit for the winding 9. When this occurs, the main armature [0 drops to deenergize the signal windings 2 and to place the system in condition for sending another signal impulse. When the station contacts Ila and I'll) again separate, due to continued rotation of the cam wheel, the increased current through the controller winding 9 again draws up the armature H] to send a second signal impulse, and this action is repeated in accordance with the number of cam projections on the wheel 18.

Thus the signal impulses are sent on the brealing of the circuit between the station contacts, rather than upon the re-closure of the station contacts, as previously described with reference to Fig. 1. As the cam wheel [8 comes to rest with the cam projection i8 holding the station contacts closed, the shunt resistor 31 is restored to the circuit and the main armature I6 remains in its lower position, preparatory to the next operation of the sending station l5. Obviously, the simplified arrangement of Fig. 6 is equally effective with the arrangement of Fig. 1 in the sending of signal impulses, with only somewhat lessened supervision of the circuits of the sending stations l5. That is to say, any breaks in the sending station circuits will give one impulse of the alarm signals, due to the continuous energization of the controller winding 9 with full current.

In order to disconnect the signal circuits from the source following an accidental break in any of the sending station circuits, the operating Winding 22 of a time delay cut-out device is connected between the last signal circuit and the main 4, with its contacts 20' and 2E normally held closed by the bi-thermal member 22a.

Therefore, continued flow of full current through the master controller winding 9 will automatically result in disconnection of the signal circuits from the main 4 upon release of the contacts 20 and 2| after the predetermined interval. In order to indicate the existence of such a condition, a pair of spaced contacts 38 are disposed in position to be bridged by the movable contact 2| of the time delay device upon release of this contact 2| by the bi-thermal member 22a. These contacts 38 are connected in shunt relation with the contacts 21 and 28 under the control of the auxiliary armature ll, so that their closure establishes the circuit of the trouble signal 30 in the same manner as would closure of the contacts 2'! and 28. Therefore, any breaks in the sending station circuits will first result in one impulse of the alarm signals, followed by operation of the trouble signal to indicate the abnormal condition, immediately upon functioning of the time delay cut-out device to disconnect the alarm signal circuits from the source.

Referring now to Figs. 7 and 8, there is shown the functioning of the signal system for the sending of a pre-signal in advance of a general alarm, with the system adapted to be operated by a master controller in substantially the same manner as previously described with reference to Figs. 1, 2 and 3. In Fig. 7, only one section of signals la, hereafter called the pro-signals, is adapted to be connected directly to the supply ,main 4 upon closure of the related contacts 6,

6a and 1, la. The remaining sections of signals lb, hereafter called the general alarm signals, are normally adapted to be connected to the supply main 4 only through a blocking resistor 39 of such value as to prevent operation of the signals lb upon closure of the particular contacts 6, 6a and '5', lo associated with these signals. The presignals la are located at various designated points throughout the system, while the general alarm signals lb are much more widely distributed, and the invention contemplates the operation of the pre-signals Ia only, upon actuating any sending station l5 followed by operation of the general alarm signals lb, only in the event that conditions warrant the sounding of a general alarm throughout the system.

To this end, each sending station l5 provides a pair of auxiliary contacts 40 normally open, with the contacts connected in parallel relation across the terminals of the blocking resistor 39. Each pair of contacts 4|! has associated therewith a manually operated key 4|, indicated as being in the form of a push button, and it is obvious that the bridging of either pair of contacts 48 by either key 4| will provide a shunt circuit around the resistor 39 to the supply main 4.

Assuming now that the signal system is in the condition shown in Fig. 7, that is, with all of the sending station circuits unbroken and with the several pairs of auxiliary stationary contacts 40 open, it is evident that only a small supervisory current will flow through the master controller winding 9 just as previously described with reference to Fig. 1. Assuming next that one of the sending stations I5 is operated for the purpose of sounding an alarm, it is obvious that turning of its cam wheel l8 will result in closure of the master controller contacts 6, 6a and 1, la upon full energization of the winding 9, as the code determining projections I8, 18" etc. operate the station contacts Fla and no. However, such closures of the contacts 6, 6a and I, la result in energization of only the pro-signals Ia, due to the fact that the flow of energizing current through the general alarm signals 1 b is restricted by the blocking resistor 39. In other Words, normal operation of any one of the sending stations l5 results in only sounding the presignals a as they may be distributed in various locations throughout the system.

Assuming that the pre-signals la. have started to sound in response to the operation of any sending station l5, as described above, the usual procedure in a system of this type is for one or more persons in authority to immediately proceed to the station which has been operated as indicated by the code designation. Then should it be determined that the fire, or whatever emergency has caused operation of the signal, is of such a nature as to warrant the sounding of a general alarm throughout the system, it is only necessary to depress the key 4| of the station which has just been operated, or of any other station in the system, in order to sound a general alarm. Since under ordinary conditions, the particular station initially operated to sound the pre-signals |a has completed at least one round of pro-signals by the time the persons in authority reach this station, the usual procedure for sounding a general alarm is not to operate the key 4| until one or more rounds of the code sequence have been completed, or the station has run down. Then the key 4| is operated to close the contacts 40, followed by re-winding of the station, if necessary. Since closure of the contacts 40 by the key 4| establishes a shunt circuit around the resistor 39 direct to the supply main 4, it necessarily follows that the next succeeding round of signal impulses will operate not only the pre-signals Ia, but also all the general alarm signals lb in unison. Upon completion of the sounding of one or more rounds of general alarm signals as desired, release of the key 4| at the station being operated breaks the circuit between auxiliary station contacts 40 and restores the system to its normal condition in which only the pre-signals la will be operated upon any succeeding actuation of a sending station.

Referring now to Fig. 8, there is shown a modification of the pre-signal system described above, in which the auxiliary contacts provided at the sending stations for the purpose of sending a general alarm are supervised. To this end, each sending station l5 provides a pair of auxiliary contacts 42 which are normally closed, although adapted to be opened by the manual operation of a key 43. The contacts 42 are connected in series with one terminal of a winding 44 of a relay, the other terminal of which is connected directly to the supply main 4. An armature 45 responsive to energization of the winding 44 carries a series of contact arms 46, 41 and 48 insulated from each other, and as long as the winding 44 is energized, these arms are held out of engagement with spaced stationary contacts 49, 50 and 5! respectively.

One stationary contact 49 is connected to the supply main 3, while another stationary contact 5|! is connected to the supply main 4, and the corresponding movable contacts 46 and 41, respectively, are connected to the stationary contacts 1a leading to the sections of general alarm signals lb. The other pair of relatively movable contacts 48 and 5| of the relay are connected in parallel with the contacts 2'! and 28 which control energization of the trouble signal 33.

With the apparatus connected as shown in Fig. 8, the flow of supervisory current through the closed auxiliary station contacts 42 and the winding 44 hold up the armature 45, so that upon the operation of any box station |5, only the pre-signals la are energized through closure of thetwo upper pairs of master controller contacts 5, 5a and I, la. Obviously, closure of the remaining pairs of master controller contacts has no effect on the general alarm signals |b, owing to the fact that contact arms 45 and 41 are held out of engagement with stationary contacts 49 and 50, respectively, by the armature 45. However, upon separation of the auxiliary contacts of the station being operated by the key 43, the resulting deenergization of the relay winding 44 permits the contacts 46, 4e and 4?, 50 to engage, thereby connecting the sections of the general alarm signals lb for operation in unison with the pro-signals la.

Since closure of contacts 48 and 5| serves to establish a closed circuit around the normally open trouble signal contacts 21 and 28, it follows that the trouble signal 30 will be operated upon any break in the circuit of the Winding 44. In other words, the trouble signal 39 will be operated upon any break in the supervisory circuit extending through the auxiliary sending station contacts 42, irrespective of Whether this break be caused by accidental means, or by the operation of a key 43 for sending a general alarm.

From the foregoing, it is apparent that by the present invention there is provided an improved supervised alarm signal system of either the presignal or general alarm type characterized by its ability to automatically indicate the occurrence of any abnormal circuit condition, without operating the alarm signals so as to give a false alarm. Due to the utilization of a single energizing winding for the master controller, the simplicity and reliability of the system is greatly enhanced.

We claim:

1. In an electric signalling system, the combination with transmitting stations including normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller having a winding in a closed supervisory circuit including said stations and signals, and signal energizing circuits including normally open contacts operable by said controller, with the flow of supervisory current through said controller winding being insufficient to close its contacts, of means responsive to each successive opening and closing of the circuit through the contacts of an actuated station to increase the energization of said controller winding and cause said controller contacts to close said signal circuits.

2. In an electric signalling system, the combination of a pair of supply mains, one of which is grounded, transmitting stations including normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, and a controller having a winding in a closed supervisory circuit including said station contacts and signals, with one terminal of said winding connected to the grounded main, and signal energizing circuits including normally open contacts operable by said controller, with the flow of supervisory current to said controller winding being insufficient to close its contacts, of a resistor in the supervisory circuit between the ungrounded main and said signals to prevent operation of said signals upon grounding of a signal, with said controller contacts open.

3. In an electric signalling system, the combination With impulse-transmitting stations providing normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller having a winding in a closed supervisory circuit including said station contacts and signals, and signal energizing circuits including normally open contacts operable by said controller, with the flow of supervisory current through said controller winding being insufficient to close its contacts, of means responsive to the opening and closing of the contacts of an actuated station to increase the energization of said controller winding and cause its contacts to close said signal circuits.

l. In an electric signalling system, the combination with impulse-transmitting stations providing normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller having a winding in a closed supervisory circuit including said station contacts and signals, and signal energizing circuits including normally open contacts operable by said controller, with the flow of supervisory current through said controller winding being insuflicient to close its contacts, of means responsive to the opening and closing of the contacts of an actuated station to increase energization of said controller winding and cause its contacts to close said signal circuits, a trouble indicating signal and means responsive to any interruption of the flow of supervisory current through said controller winding to indicate such interruption of the energization of said trouble indicating signal, with said signal energizing circuits remaining open.

5. In an electric signalling system, the combination with impulse-transmitting stations providing normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller having a winding in a closed supervisory circuit including said station contacts and signals, and signal energizing circuits including normally open contacts operable by said controller, with the flow of supervisory current through said controller winding being insuflicient to close its contacts, of means responsive to the opening and closing of the contacts of an actuated station to increase the energization of said controller winding and cause closure of its contacts, and means in the energizing circuits of certain of said signals to prevent their operation upon initial closure of said controller contacts.

6. In an electric signalling system, the combination with impulse-transmitting stations providing normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller having a winding in a closed supervisory circuit including said station contacts and signals, and signal energizing circuits including normally open contacts operable by said controller, with the flow of supervisory current through said controller winding being insufficient to close its contacts, of means responsive to the opening and closing of the contacts of an actuated station to increase the energization of said controller Winding and cause closure of its contacts, a resistance in the energizing circuits of certain of said signals to prevent their operation upon initial closure of said controller contacts, and additional contacts at the actuated station to cut out said resistance and permit said first-named signals to be energized simultaneously with the other signals upon subsequent closure of said controller contacts.

7. In an electric signalling system, the combination with transmitting stations, including normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller providing normally open contacts and a winding in a closed supervisory circuit including said station contacts and signals, and normally open signal energizing circuits including the open con tacts of said controller, with the flow of supervisory current through said controller winding being insufiicient to close said controller contacts, of means responsive to the actuation of a station to interrupt the flow of supervisory current through the station contacts and to bring about an increase in the energization of said controller winding and cause its contacts to close said signal circuits.

8. In an electric signalling system, the combination with transmitting stations including normally closed contacts and means for repeatedly opening and closing said contacts upon actuation of a station, signals, a controller providing normally open contacts and a winding in a closed supervisory circuit including said station contacts and signals, and normally open signal energizing circuits including the open contacts of said controller, with the flow of supervisory current through said controller winding being insufiicient to close said controller contacts, of means responsive to the opening and closing of the contacts of an actuated station to interrupt the flow of supervisory current through the 10 station contacts and to bring about an increase in the energization of said controller winding and cause its contacts to close said signal circuits, and means including part of the magnetic circuit of said controller and responsive to any interruption of the flow of supervisory current through said controller winding to indicate the occurrence of a fault in the system, With said signal energizing circuits remaining open.

JOHN H. WHEELOCK. FRANK SCHERMA.

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