US3028585A - Alarm and annunciator system - Google Patents

Description

April 1962 R. J. MARMORSTONE 3,028,585

ALARM AND ANNUNCIATOR SYSTEM 2 Sheets-Sheet 1 Filed March 28, 1955 INVENTOR.

.57 W 5 M221) A 16L April 1962 R. J. MARMORSTONE 3,028,585

ALARM AND ANNUNCIATOR SYSTEM 2 Sheets-Sheet 2 Filed March 28, 1955 ur! z United States Patent 3,028,585 ALARM AND ANNUNCIATOR SYSTEM Robert J. Marmorstone, Chicago, Ill., assignor, by mesne assignments, to I51, Incorporated, Los Angeles, Caliti, a corporation of Delaware Filed Mar. 28, 1955, Ser. No. 497,149

Claims. (Cl. 340-213) This is a continuation-in-part of application Serial No. 414,704, filed March 8, 1954- by Albert P. Sperry and Robert J. Marmot-stone on an Alarm and Annunciator System, now abandoned.

This invention relates to annunciator systems and more particularly to an annunciator system which includes relay apparatus usable with either normally closed or normally open signal contacts.

Annunicator systems usually comprise a condition-responsive element, such as a thermocouple or the like, associated with each test point or variable to be monitoredand which includes a pair of cooperating electrical contacts which open or close when the associated test point or variable is normal and which respectively close or open when the associated test point or variable is abnormal. Each set of signal contacts or condition-responsive contacts are associated with relay circuitry which in turn control various audible and visual alarm annunciator units. Where a large number of test points are involved, such as is common in power plants and other large industrial installations, the various relay circuits directly controlled by the signal circuits are tied into common busses wherever possible and brought to a central indicatingand control panel where, by means of indicating lights or the like, an operator may monitor the various test points from a central location and may perform variou control operations with respect thereto.

For example, it is common to include on such control panel a separate light for each test point which lights up when the associated test point becomes abnormal and an audible alarm common to all of the test points which is sounded the instant any test point becomes abnormal. This attracts the operators attention to a particular part of the control panel which indicates the location of the abnormality. An acknowledge push button is generally provided which de-energizes the audible alarm so that the alarm may be operated by the initiation of other abnormal conditions for other test points in the system.

Certain industrial applications, for example, power plant applications, prefer to utilize normally open signal contacts to minimize drain on the battery system used for energizing the annunciator circuits; on the other hand, many chemical and other industries prefer to utilize normally closed alarm contacts where the circuit in which the contacts are located draw current in their normal position. Heretofore, the relay apparatus which con trolled the visual and audible annunciator units were variously designed for signal contacts having normally open and normally closed contacts, respectively. Inaccordance with this invention, the same relay apparatus produces identical operation of the visual and audible annunciator units when used on normally open or normally closed contacts. This results in standardization of the" components making up the annunciator system.

The foregoing and other features of the invention will be understood more clearly upon a study of the description which follows with reference to the drawings appended hereto. It should be understood that a number of specific features are here described and illustrated as being preferred for certain purposes, which may be omitted without deviating from the broader aspects of theinvention.

In the drawings:

FIG. 1 is a schematic diagram of one embodiment of the invention;

FIG. 2 is a modified form of the embodiment of FIG. 1; and

FIGS. 3 and 4 are across the line diagrams of a third embodiment of the invention with diiferent jumper connections to adapt the same relay apparatus for use on normally open and normally closed contacts.

Referring first to FIG. 1: I

A panel or cabinet 10 is provided to interconnect a series of signal switches 11A, 11B, etc., with a corresponding' series of visual alarm annunciators 24A, 24B, etc. forming part of an alarm light cabinet or panel 25,- preferably close to or even integral with the basic panel or cabinet 10. Each signal switch 11A, 11B',etc., is suitably incorporated in or-associated with a machine or field unit to be protected by the alarm system, by well known thermostatic means, liquid pressure responsive means or equivalent apparatus (not shown).

Animportant feature of the present system is that any one, more or all of the signal switches 11A, 11B, can be normally open or closed and that nevertheless no modi fication whatsoever is required in the structure and arcooperates with the normally open or normally closed signal switch 11A, 313', etc.

At a suitable location, usually at a central point in the plant, an audible alarm device such as a loud horn 12- is provided in order to alert practically the entire plant personnel whenever any one of the signal switches 11A, 11B, etc., changes from its normal (open or closed) to its abnormal (closed or open) position. By means of the three relay construction of the plug-in unit, such horn operation is initiated in the starting or alerting phase of each alarm program, and also in a return alarm or allclear sounding phase thereof, regardless whether the alarm initiating signal switch 11A, 113, etc., is normally openor normally closed; no modification of the wiresystem whatsoever being required and utilized in this connection.

At or near said central location there is also'provided a push-button station 13 in order to allow the plants'uperintendent to acknowledge the alarm alert and silence the horn, and also suitably to modify the other or visual alarm announcements, caused by the alerting phase, as soon as the alert has been noted and remedial action started. For such and related purposes the push-button station contains a push button 15, the interconnections of which-will best be explained hereinafter. It may be noted at this point that the same push button also serves to reset the system in its normal position when a return alert hasbeen sounded and visually indicated, which last mentioned sounding and visual indication is occasioned by the return of the alarm initiating signal switch. 11A or 1113, etc., into its normal (closed or open) position.

Thus the complete alarm program according to the present system, which can be caused by any of the nor mally open or normally closed signal switches 11A, 11B moving into abnormal and then back to normal position, comprises the following phases:

(1) A signal switch 11A, 1113", etc., moves into abnormal position; this causes transmission of audible alerting signals to the plant and control station through the horn 12 and of a corresponding visual alerting signal to the control station through the corresponding light unit 24A; the preferred visual indication of this phase being flashing of this light unit (alert or alerting phase).

Patented Apr. 3, 1962 (2) The superintendent acknowledges the alert by depressing the push button this causes transmission of a primary alarm modifying signal to the plant by silencing the horn 12 and transmission of a primary alarm modifying signal to the control station by modification of the announcement at 24A, which at this time preferably becomes steadily illuminated (acknowledged condition).

(3) The signal switch responsible for the original alert moves back to normal position; this causes transmission of a new audible or all-clear signal to the plant through the horn 12 and to the control station through the aforementioned light unit which begins to flash again (return alert).

(4) The superintendent depresses the push button 15 again, which at this time transmits final reset signals, different from those caused by the first depression of the push button. The horn is silenced again and the aforementioned alarm light unit at this time is extenguished (reset or normal position).

For the detailed circuit analysis which follows, it may be assumed that the signal switch 11A is normally open and that the signal switch 11B is normally closed.

The signal switch 11A, is interconnected with its corresponding light unit 24A by a relay plug-in device 17A. Switch 11B is similarly interconnected by a relay unit 17B. These relay plug-in units 17A, 17B, etc., are identical with one another in every respect, as shown, although their starting switches 11A, 11B operate in manners basically opposite to one another as mentioned.

Eight bus wires are shown within the panel or control box 10. In addition, there is provided a hot wire H which need not be connected to the different relay plug-in units 17A, 17B, etc, and which accordingly is shown outside the panel, thereby limiting the system of bus wires installed on the panel. This system comprisis: A horn control wire R; a light flashing wire F; a lamp test wire T; an acknowledgment and reset control wire C; and a neutral wire N. These five bus wires C, R, F, T and N are the only bus wires installed within the cabinet which are utilized in the operation to be described hereinafter. In the interests of standardization, which a slightly amplified system or group of systems to be described hereinafter, there are also shown bus wires K, PR and RR, on the control panel, which can be disregarded for present purposes. However, it is preferred to interconnect them with the corresponding terminals on the plug-in sockets, in manner identical with that to be described hereinafter in connection with FIGURE 2; the material and labor involved in such standardization being insignificant in cost and conducive to much greater simplicity and safety in mass production and mass testing.

For the flashing operation mentioned above, there is provided a flasher switch 178 interposed between the neutral wire N and the light flashing wire F, and operated by a flasher motor 17M which is connected in parallel with the horn 12, between the neutral wire N and the horn wire R. A flasher relay 17F is formed by this flasher switch and flasher motor and it is usually sufiicient to provide a single flasher relay of this kind for a very large number of individual alarm relay units 17A, 178, etc., cooperating therewith.

The reset and acknowledgment control wire C is connected with the hot wire H through its push button 15 which is normally closed, thereby normally making this control wire the source of electric current for the entire system, together with the neutral wire N.

Coming now to the details of the branch circuits interconnecting the foregoing major parts of the alarm system, and referring particularly to the branch ciruits associated with the normally open signal switch 11A:

The relay or plug-in unit 17A has eleven connector plugs, inserted in corresponding connector socket terminals, all of which are schematically shown at X-l to 4 X-11. Connected with these plugs the unit 17A has three relay coils A, B, and C, each of which has one terminal connected with the neutral wire N by the plug X4.

The other terminal of the coil A is connected by the plug X10 with one side of the signal switch 11A, the other side of which is connected with the hot wire H. A terminal Y-10A is interposed on this connection, between the plug X10 and the switch 11A, and similar terminals Y-ZOB, Y-10C, etc., are provided for the similar plugs X10 of the other relay units 17, etc. The entire series of terminals Y-10A, Y-10B, etc., is incorporated in a single compact terminal unit Y, such as an insulating strip with suitable binding posts or the like, which preferably is located in the back of the cabinet 10 at a conveniently accessible point in order to facilitate installation, interconnection with different locations in the field, maintenance and checking.

The control wire C, through the connector plug X3, is connected with three circuits, two of which have shunts. One of these circuits leads to the free terminal of the coil B and has a normally open switch B1 interposed thereon, and a normally closed switch A1 interposed on a shunt around B1. The second of the three circuits mentioned leads to the horn wire R and has interposed thereon normally open switches B2 and C1 in series. The last of the three circuits mentioned leads to the free terminal of the coil C and has the normally open switch A2 thereon and the normally open switch C2 on a shunt around A2.

It will be understood that all switches identified as A1, A2, etc., are located within the plug-in unit 17A and controlled by the coil A, and correspondingly all switches identified as B1, C1, etc., are similarly located and controlled by the corresponding coils B, C.

Connections to and for the lamp unit 24A are made through the aforementioned jack 20-9A which can be inserted either in a corresponding socket terminal of a socket 20-9 or in a socket 20-11; said sockets being interconnected with corresponding terminals X9 and X11 on the plug-in unit 17A. Two alternative connections are thus provided, one of which is used in the present case where the signal switch 11A is normally open, while the other is utilized in connection with the normally closed switch 113. The sockets 20-9 are used in connection with the normally open signal switches 11A, etc., and their corresponding relay units 17A, etc., whereas the sockets 20-11 are used with the normally closed signal switches.

In either case connections are made so that if desired, a single lamp, with a backlighted nameplate in front, can distinctively and clearly indicate the several states or phases of any alarm initiated by the corresponding switch and relating to a clearly identified plant unit.

For these purposes the lamp terminal plug X9 connected with the corresponding lamp through the socket 20-9 has two primary branches connected therewith within the relay plug-in unit 17A, containing respectively normally open and normally closed portions A3 and A4 of a double-throw switch. The normally open portion A3 in turn has two branches within the unit 17A containing respectively normally open and normally closed portions B3 and B4 of another double-throw switch. The latter portions are connected respectively through the connector X7 with the flasher bus F and through the connector X4 with the neutral wire N. The normally closed portion A4 of the first mentioned double-throw switch has another pair of branches in the relay unit, containing respectively the normally open and normally closed parts C3, C4 of still another double-throw switch, connected respectively by the plugs X7 and X5 with the flashing wire F and the testing wire T.

The interconnection of the common terminal X9 with the corresponding lamp 24A could theoretically be obtained by a terminal strip arrangement similar to that shown at Y for the corresponding signal switch correctrons. However, there is a practical difierence between the signal switch and signal lamp connections. The former inherently require individual hook-up arrangement with remote field stations, whereas the latter are desirably united in a compact panel or a lamp bezel adjacent the panel 10, and it is frequently desirable to establish, separate and re-establish connections between the relay and lamp panels 19, 25, for testing and other purposes. It is for this reason that the use of jack or plug connectors 20-91%, etc., is preferred at this point. It will also be noted that the corresponding sockets 2tl9, 2041 are interchangeable with corresponding sockets shown in the co-pending application Serial No. 312,821.

The system of branch circuits in the unit 17A, connected with the switch 11A and lamp 24A, is completed by a circuit and shunt around the same connected with the free terminal of the coil C. Said circuit contains the normally open switch A2 while the shunt contains the normally open switch C2. Connection is thus made to the acknowledgment and reset control wire C, through the terminal X3.

The horn 12 and control switch 15 as well as a lamp test switch 16, to be described hereinafter, are desirably connected with the wiring of the panel in manners similar to that used for the connections of the signal switches 11A, 11B, etc., that is, through a terminal strip W arranged to facilitate individual field connections of permanent nature, as indicated for instance at WN, WR for the horn 12.

The details of the alternate lamp circuit and its terminal X31, connected with the normally closed signal switch 115 and corresponding lamp 24B, will be described hereinafter. At the present point it may be noted that the panel 1% has, in addition to the bus wires described above, a row of identical plug-in devices 17A, etc., the system of lamp plug-in sockets 28-9, 23-11, the flasher relay 17F, a pair of terminal strip units W and Y for connection with the alarm equipment 12, 15, 16 and the signal equipment 11A, 118 respectively, and of course a series of plug-in sockets, diagrammatically shown at X1, etc., for the plug-in relay units 17A, 17B, etc.

OBERATEON WlTH NORMALLY OPEN SIGNAL SWITCHES The signal switches 11A, etc., as mentioned are normally open. The corresponding jacks 209A, etc., as mentioned, are inserted in the sockets 209.

The corresponding lamp units 24A, etc., are normally off. The plant-wide audible annunciator 12 of course is normally or In the relay units 17A, etc., the coils A are connected and disconnected through the signal switches 11A; the coils B are normallyenergized through normally closed switches A1 and self holding through switches B1; and the coils C are connectable through normally open switches A2 and self holding through switches C2; the circuits of connecting and self-holding switches A1, B1, A2 and C2 being controlled by the push button 15.

Accordingly it will be seen'tha't as a result of the normally open condition of the signal switch 11A, the coil A is normally tie-energized; the coil B is normally energized through Al; and the coil C is normally de-energized.

As a further result it will be seen that the bus wires R and F are normally de-energized, all connections thereof containing at least one normally open switch C1, A3 and C3. Thus neither horn actuation nor flashing of lamp 24A, etc., occurs normally. Nor is lamp 24A steadily illuminated in the normal position, the remaining connections thereof being open at B4 and 16 respectively.

Upon the occurrence of an abnormal condition in the protected plant unit or machine, the signal switch 11A closes. This energizes the coil A, this in turn closes the switch A2 thereby energizing the coil C. The energized coil B remains energized at B1. Thus all coils A, B and C are now energized. Due to the closing of the switch C1 and the switch B2, the horn wire R is energized and the horn 12 begins to sound. In parallel therewith the flasher motor 17M begins to operate. The switches B3 and A3 connecting the lamp 24A with the flashing bus wire F are now closed, and the lamp 24A begins flashing (a steady illumination of lamp 2413, etc., may simultaneously exist in connection with another signal switch 118', etc., but no interference will occur, the flashing connections and steady illuminating connections of the lamps being made through separate wires F and N and separate relay switches as described).

Acknowledgment of the alarm, by momentarily depression of the push button switch 15, momentarily de-energizes the control bus C and thereby the plugs X3. This results in momentary de-energization of the coils B and C. The coil B remains de-energized, its self-holding switch B having opened and its starting switch A1 being held open by the energized coil A. The coil C is promptly re-energized upon release of the push button 15, through the switch A2 which is held closed by the coil A. Thus the coils A and C are energized and the coil 33' is de-energized during the acknowledged alarm condition. The horn sounding and flashing connections are eliminated thereby as described, whereas thelamp 24A is now connected to the neutral wire N through the switches A3 and B4 and to the hot wire H through the reclosed acknowledgment switch 15. Thus during the acknowledged alarm condition further disturbance of the plant personnel by sounding of the horn is avoided whereas the lamp 24A continues to indicate the existence and exact location of a danger condition.

When that condition has been removed, the signal switch 11A opens again, thereby de-energizing the coil A again. This re--energizes the coil B through the normally closed switch A1, while the coil C remains energized through the seal-in switch C2. Thus the return.

alarm position which now follows is characterized by deenergization of the coil A and energization of the coils B and C. The one bus F and flasher relay 17F are connected again, as before; the horn sounds and the lamp 24A shows a return alert or all-clear signal for the unit previously alerted, while the previous steady illumination of the lamp 24A is broken at B4.

Renewed operation of the push button 15 again m0- mentarily de-energizes the coils B and C. This time the coil B is re-energized through the normally closed switch A1 while the coil C still is de-energized at A2. Thus the normal position of the system, wherein only the coil B is energized, is re-established and all annunciators are off.

It will thus be seen that the sequence of operations described up to this point can be summarized as follows:

Operation With Normally Open Signal Switches Phase A B 0 24A 12 Alert E E E Flashing E Acknowledged Alarm E I) E Steady... D Return Alert D E E Flashing" E Reset (Normal) D E D On D It will be understood that in this chart the letter D signiiies dc-energized while the letter E signifies energized.

OlERATlON WITH NORMALLY CLOSED SIGNAL SWICTHES relay unit 17A, and identically in the unit 17B utilized in the present instance, two circuit branches having interposed thereon the normally closed and normally open portions A and A6 of a double-throw switch controlled by the coil A. The branch AS in turn has two branches having interposed thereon the normally open and normally closed sides C5 and C6 of a double-throw switch operated by the coil C, connected respectively through plugs X-7 and X-4 with the flashing and neutral wires F, N. The other branch A6 has two branches with the normally open and normally closed sides B5, B6 of a double-throw switch controlled by the coil B; connected respectively through the terminals X-7 and X-5 with the flashing and test wires F, T. It may be noted that the connections are substantially the reverse of those shown at X-9. Thus it will be understood without further detailed analysis of the corresponding circuits that with the present'method of plugging in at 20-11 and without change as to the horn 12, there is obtained the following:

Operation With Normally Closed Signal Switches Testing of the difierent lamps 24A, 245, etc., whether connected at 20-9 or 29-11, is conveniently effected by depression of the push button 16, which as shown is interposed between the neutral wire N and the test wire T. If such depression of the push button occurs during an otherwise unenergized condition of the lamps, such as the normal position of the system, it energizes the lamps 24A connected at 20-9, through the switches C4 which in this method of interconnection are normally closed. It likewise connects the lamps 24B plugged in at 20-11 through the switches B6, which in this latter condition are normally closed. Thus there is provided a convenient single testing operation, regardless of the other variations of announcements as described.

THE MODIFICATION OF FIGURE 2 The jacks 20-9A, 20-9B, etc., can be replaced by the poles of single-pole double-throw switches 208A, 265B, etc., preferably of the toggle switch type, so that it is not even necessary to modify the insertion of jacks and corresponding cords when changing over from normally open to normally closed arrangements as at 11A, 1113'. In this modification it is merely necessary to provide on or near the panel 10 a double-throw switch 205A, etc. for each annunciator light 24A, and to interconnect the common leg or permanently connected terminal of each switch 208A, etc. with the respective light 24A, etc. (in the same manner as the sockets 20-9 or 28-11 are connected therewith by the jacks 20-9A, etc. in FIGURE 1). The sockets 20-9, 20-11 can be omitted; the wires C-9, C-11 from the relay plug-in terminals X-9, X-ll can be connected with the alternate legs or terminals of the corresponding switches 208A, etc., with or without terminal strips 20-9A, 20-11A interposed, depending on whether the switches are on or away from the panel 10.

THE MODIFICATION OF FIGURES 3 AND 4 In the embodiment of FIGS. 3 and 4, the same plug-in unit is utilized with normally open or normally closed field contacts. However, the number of relays and the number of contacts per relay are reduced over the embodiment shown in FIGS. 1 and 2. Further, in the modification of FIGS. 3 and 4, the alarm light 24a remains fixed in place in the circuit when operating from normally closed or normally open field switches. Instead of relocating the alarm light when changing from normally open to normally closed signal switches, or vice versa, the jumper lead I L connected to the No. 8 plug-in terminal of the plug-in unit 17a is relocated from its position in connection with the H supply line where normally open field switch contacts are utilized to connection with the N supply line (see FIG. 4) when used with normally closed field contacts. No other changes are required.

The same plug-in unit is usable with either normally open or normally closed signal switch contacts in the embodiment of FIGS. 3 and 4, because of the particular arrangement of the field signal contacts in the circuit and because of the connection of the addition of a series resistor R in the A relay coil circuit between the N and H supply lines. In this embodiment, the field contacts, whether normally open or normally closed, are connected between the H supply line and the terminal of the resistor R supply line and the terminal of the resistor R which is remote from the resistor terminal connected to the N supply line. The resistor R and the field switch contacts are therefore always in series across the supply line. When the jumper lead IL is connected to the H supply line as shown in FIG. 3, where normally open field switch contacts are used, the A relay coil is in parallel with the field switch contacts so that the A relay coil is de-energized upon the initiation of an abnormal condition. On the other hand, where the jumper lead IL is connected with the N supply line as in the normally closed field switch arrangement of FIG. 4, the A relay coil is in series with the field contacts so that the opening of the field contacts in response to an abnormal condition of a variable also results in the tie-energization of the A relay. The identical annunciating sequence therefore exists whether the system is connected with normally opened or normally closed field switch contacts.

Refer now to FIG. 3 for a more complete description of the circuitry. As there shown, each relay plug-in unit 17a has only two relays, namely an alarm relay A and an acknowledgment relay B. The alarm relay A is connected in a circuit extending from the N supply line through a current limiting resistor R, the No. 2 plug connector of the relay unit 17a, the relay coil A, the No. 8 plug connector of the relay unit 17a, through the jumper lead JL connected with the H power line. The field contacts 11A have one terminal connected to the H supply line and the other terminal connected in the line leading to the No. 2 plug-in terminal of the plug-in relay unit 17a. The field contacts 11A are therefore connected in shunt with the A relay coil so that upon the existence of an abnormal condition of the variable which controls the field contacts, the field contacts will close shunting out the A relay coil from the supply line. The resultant de-energization of the A relay results in the energization of the horn 12 and the flashing on indication of the alarm light 24A.

The energization circuit of the horn 12 can be traced from the N supply line, through the born 12, the common R bus, the No. 6 plug-in terminal of a relay unit 17a, the normally open but then closed contacts B2 of the acknowledge relay coil B, the then closed normally closed contacts A2 of the alarm relay, the No. 3 plug-in terminal of the relay unit 17a, the common acknowledge bus C, and through the normally closed acknowledge push button switch 15 leading to the H supply line. The expression normally closed or open relay contacts means that the relay contacts have these respective conditions when the associated relay is de-energized.

The energization circuit of the alarm light 24A can be traced from the N supply line through the interrupter contact 17111 of the flasher unit 17 common flasher bus F, the No. 7 plug-in terminal of the relay unit 17a, the normally closed contacts A-S, the then closed normally open contacts 13-4, the No. 1 plug-in terminal of relay unit 17a, the alarm light 24A, the common acknowledge bus C, and through the then normally closed acknowledge push button switch 15 leading to the H supply line. The flasher contacts 17m) are active because the flasher motor 17m is connected in parallel with the horn between the N supply line and the common horn bus R.

The energization circuit of the acknowledge relay B can be traced from the N supply line, the No. 4 plug-in terminal of the relay unit 170:, the acknowledge relay coil B, the then closed normally open holding contacts B 1, the No. 3 plug-in terminal of the relay unit 17a, the common acknowledge bus C, and through the normally closed push button switch 15 leading to the H supply line.

When the operator is attracted by the sounding of the horn 12 he depresses the acknowledge push button 15 which breaks the holding circuit of the B relay to deenergize the same. Release of the acknowledge push button 15 does not result in the re-energization or" the acknowledge relay B because the normally opened contacts Al in parallel with the B relay holding contacts B1 are open due to the tie-energized condition of the l A relay.

The de-energization of the B relay changes the flash ing indication or" the alarm light 24A to a steady-on condition and tie-energizes the audible alarm 12. The latter occurs because the aforementioned normally open contacts B2 are then opened which interrupts the energization circuit of the audible alarm 12.

The alarm light 24A is in a steady-on condition because of the establishment of an energization circuit extending from the N supply line through the No. 4 plug-in terminal of relay unit 17A, the then closed normally closed contacts A7, the then closed normally closed contacts E5, the alarm light 214A, the common acknowledge bus C and through the then closed acknowledge push button switch 15 leading to the H supply line. The circuit leading to the flasher bus F is interrupted because of the opening of normally open contacts B4 which connects with the flasher bus through the then closed normally closed contacts A5.

Upon return to normal of the variable involved, the field contacts 11A will open thereby re-energizing the alarm relay as the shunt circuit including the field contacts open.

The re-energization of the A relay efiects the re-energization of the B relay as the normally open contacts A1 close. The B relay then seals in through its holding contacts B1. The audible alarm 12 is not sounded at this time because the normally closed contacts A2 have opened. The alarm light 24A is extinguished because of the opening of contacts A7 and B in one of the alternate energization circuit branches of the alarm light 24A. The other branch of the energization circuit of the alarm light 24A is unenergized because of the opening of normally closed contacts A5. 7

To test the operation of the alarm light 24A, the test push button 16 is depressed which if the alarm light 24A is in operating condition will energize through a circuit extending from the N supply line, the push button 16', the common test bus T, the No. 5 plug-in terminal of the relay unit 17A, the then closed contacts A4 (normal operation is assumed), the then closed contacts E4, the N0. 1 plug-in terminal of the relay unit 17A, the alarm light 24A, the common acknowledge bus C, and through the then closed acknowledge push button switch leading to the H supply line.

The circuit shown will give an alarm also upon failure of either the A or B relay coils. Since the A relay coil is normally energized, failure of this coil will result in contacts A3 which shunt the normally opencontacts B2 and the normally closed contacts A2 in the energization circuit of the audible alarm 12. With the A relay energized, failure of the B relay will result in the energization of the audible alarm because of the establishment of this new branch circuit upon the closing of the normally closed contacts B3 in series with the then closed normally open contacts A5.

Failure of the B relay during energization of the A relay will also result in the flashing of the alarm light 24A due to the establishment of an energization circuit therefor extending from the N supply line, the interrupter Contact 17mf of the flasher motor unit, the common flasher bus F, the No. 7 plug-in terminal of the relay plug-in unit 17A, the then closed normally open contacts A6, the normally closed contacts B5, the alarm light 24A, the common acknowledgment bus C and through the normally closed push buttin switch 15 leading to the H supply line.

As previously stated, it is unnecessary to review the operation of the annunciator circuit when used with n0rmally closed field contacts because in the latter situation opening of the field contacts during an abnormal condition results in the de-energization of the alarm relay A since the field contacts are then in series with the A relay coil due to the relocation of the jumper lead IL. The relay apparatus thus operates in the same manner whether normally open or normally closed contacts are used. I

It should be understood that numerous variations may be made in the circuitry above described without departing from the spirit of the invention.

I claim:

1. Annunciator apparatus for monitoring a series of field stations, a signal switch for each field station adapted to assume a normal and an abnormal position, respective annunciator means associated with said signal switches for indicating the position of the corresponding signal switch, manually operable control switch means for modifying the indication of said annunciator means, relay control apparatus for each signal switch and associated annunciator means, each relay control apparatus having signal switch connecting terminal means adapted for selective connection to signal switches having normally closed or normally open contacts, a first set of annunciator connecting wires leading'from said respective relay control apparatuses, a second set of annunciator connecting wires leading from said respective relay control apparatuses, means for selectively connecting said respective annunciator means to one or the other of said sets of annunciator connecting wires depending on whether said signal switch connecting terminal means are connected to normally open or normally closed signal switches, means including means interconnecting said first set of annunciator connecting wires with their associated relay control apparatus for providing a given sequence of respective annunciator indications on the associated annunciator means during the following sequence of operation of a normally closed signal switch and said control switch means:

(a) opening of such signal switch,

(b) manual operation of said control switch means,

(0) closing of said signal switch, and then (d) manual operation of said control switch means, and means interconnecting said second set of annunciator connecting wires with their associated relay control apparatus for providing said same sequence of annunciator indications on the associated annunciator means in the same order during the following sequence of operation of a normally open signal switch and said control switch means:

(a) closing of such signal switch (b) manual operation of said control switch means (c) opening of said signal switch, and then (d) manual operation of said control switch means.

2. Apparatus as described in claim 1 wherein said selective connecting means comprise a number of doublethrow switch contacts respectively connected with the corresponding annunciator means and adapted to make alternate connection with said terminals of the associated pair of connecting terminals.

3. Apparatus as described in claim 1 wherein said connecting terminals and selective connecting means are cooperating plug and socket connectors whereby the annunciator means associated with each signal switch may be selectively connected with either terminal of the associated pair of connecting terminals.

4. Apparatus as described in claim 1 wherein each relay control apparatus comprises three separately energizable and de-energizable multi-pole relays of the two position type, and circuit means interconnecting said relays and their associated contacts with said signal switch, control switch means and annunciator means for providing at least four diiferent indications whether the signal switch is normally open or normally closed.

5. Apparatus as described in claim 4 wherein there is provided means for energizing a pair of the relays to provide one of the four indications; means for energizing one of the relays to provide a subsequent indication; means for energizing all three relays to provide the next subsequent indication; and means for energizing another pair of relays for the fourth indication.

6. Apparatus as described in claim 5 wherein the control switch means is connected in common with all of said relays.

7. Apparatus as described in claim 5 wherein said three relays are so connected that successive reversals of the corresponding signal switch and intermediate operations of the control switch means provide the following sequence:

A B G E E E E D E D E E D E D where A, B and C are the three relay coils, the A relay coil being arranged to respond directly to a change in position of the associated signal switch, D means deenergized, and E means energized.

8. Apparatus as described in claim 5 wherein said three relays are so connected as to provide the following sequence when connected to one of said types of signal switches:

U'dmm t random in drama Q by initial reversal of the corresponding signal switch, subsequent momentary operation of the control switch means, subsequent return of the signal switch to the original position and final momentary operation of the control switch means, respectively; A, B and C meaning the three relay coils, D meaning de-energized, and E meaning energized.

9. In an annunciator system, an alarm relay and an energization circuit for said alarm relay in which signal contacts are to be interposed for controlling the energization and de-energization of the alarm relay, second and third control relays and respective energization circuits therefor, annunciator means and an energization circuit therefor, acknowledge switch means and contacts of said alarm relay in the energization circuit of said second and third relays and adapted to de-energize said second relay upon actuation of said acknowledge switch means when the alarm relay is in one of its positions and adapted to tie-energize the third relay when the alarm relay is in the other one of its positions, the energization circuit of said annunciator means having two alternate branches each containing contacts of all three relays, one of said branches being arranged for operation with normally closed signal contacts and the other branch being arranged for operation with normally open signal contacts, and terminal means for selectively connecting said annunciator means in either one of said branch circuits.

10. In an annunciator system comprising a set of signal contacts adapted to assume opposite positions when the associated variable is normal and abnormal, respectively, and an alarm relay and an energization circuit therefor in which said signal contacts are interposed for controlling the energization and de-energization of the alarm relay, second and third control relays and means for holding the same in one of their states of operation, respective energization circuits for said second and third relays, said alarm relay having a set of contacts in the energization circuit of said second relay which operate the same into its holding position when the alarm relay is in one of its positions, the alarm relay having contacts in the energization circuit of the third relay which operates the third relay into its holding position when the alarm relay is in the opposite position, annunciator means and an energization circuit therefor, the energization circuit of said annunciator means having two main branches in which the annunciator means may be selectively interposed, each of said branches including contacts of said alarm relay and said second relay arranged to energize said annunciator means when the alarm relay is actuated to one of its positions and also having other contacts of said alarm relay and contacts of said third relay arranged to energize the annunciator means when said alarm relay is actuated to the other one of its positions, one of said main branches having contacts of said second relay arranged in a circuit which modifies the signal of the annunciator means when the second relay is in its non holding position, and the other main branch circuit including contacts of said third relay which are arranged to modify the signal of the annunciator means when the third relay is in its non-holding position, and acknowledge switch control means in the energization circuits of said second and third relays and arranged to actuate said relays momentarily to their non-holding positions.

References Cited in the file of this patent UNITED STATES PATENTS 1,640,325 Janson Aug. 23, 1927 1,686,492 Janson Oct. 2, 1928 1,920,153 Clokey July 25, 1933 2,600,132 Seaton June 10, 1952 2,813,263 Warren Nov. 12, 1957

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