US2419957A - Electrical protective alarm system - Google Patents

Description

May 6, i947.

H. M. LAFORD ELECTRICAL PROTECTVE ALARM SYSTEMl 2 Sheets-Sheet 1 Original Filed May 6, 1939 INV ENT OR. -ferbcr lmaford ATTORNEY P ZD JOEZOD plil III. om, o zw May 6, 1947. H. M. LAFoRD ELECTRICAL PROTECTIVE ALARM SYSTEM Original Filfed May'G, `1939 2 Sheets-Sheet 2 ATTORNEY.

Patented May 6,. i947 UNITED STATES PATENT @FFI-CE ELECTRICAL Pn'orcGrivelA rnnlvr seisrrnivr Herbert M. Laford, Bloomfield; N. assigner to:

Electro-Protective Corporati01i, Newark N. .1.,i a ccrpcrationof New J ersey @riginal applicationr May 6,-A 1939, SerzrlV No;

272,084. Divided and this'. application: July; 9;. 1943, Serial No. 493,971

SClaims: l'. This yapplication is a division ofmy application Serial'No. 272,084, iiled May 6, 1939, on Which Patent No. 2,346,171 Was granted.

Thisinvention relates 'to electrical protectivealarm systems, such as burglar alarm systems for mercantile premises.

Among the objectsof the invention is an improved eleotricalalarm system of the type used in. burglar alarm systems, and the like, which is foolproof .in operation, easy to maintain in its efficient operatingv condition,- and simple to test and supervise; such systemusing an extremely compact outdoor alarm housing for housing the batteries and the alarm sounding device which is connected through a cable to the interior of the protected premises, and so arranged that when the. cable is cut or short-circuited, the alarm de viceis actuated and automatically set in operation by the battery. in the outdoor housing; such system Ywith an outdoor housing having an alarm sounding. member in the form of a plate-.like structure. which occupies konly a negligibly small space Within the` housing; such arrangement in which the outdoor. housing. isprovided with an insulating housing lining serially connected in theprotective Wiring circuit of the system and so arranged'th'at when the outdoor housingis moved to its open position, the lining is moved with -it toy expose the` interior elements for easy inspection and servicing.

The foregoing and other objects of the invention will be best understood from the following description of exemplications thereof, illustrated in the accompanying drawings wherein Figi 1 is a diagrammatic View of an electrical protective burglar alarm system exemplifying the invention in .its protection on condition; y

Fig, 2 is a perspective view ofthe outdoor alarm housing;

Fig. 3 is a perspective View of the housingofcantileestablishments and similar premises. In

such protective system the guarded premises are provided with a protective Wiring arrangement extending along the show windows, doors, screens and other possible places of intrusion. In Fig. 1,

the` guard elements of the guarded structure in-Y eluded in the protective` systemiare indicated" schematically by the` Window -foil .lacings I9, l |,l

(Cl. IWL-314)' i2`door, window andv screen tamper switches shown in the formof spring contactors at i344,

Y tor ibeing, for instance, thev spring contactor ofthe.. main entrance door into the premises. Tnese'guard-elements lil-ll, l2, i3; ill, l5 are in terconnected into. a. protective wiring circuit which'ds provided with'a. control unite, usually located inside the protected premises, andis connected, by a lead-covered' multiconductor cable to ,an .alarm sounding unit 'l which is Yusually disposed on the exterior` ofthe protectedpremises solthaty the sounded alarm'will be notcedrby the passingpeople, beingmounted high up von'a Wall.

forl instance,so that it can be reached onlyA by a tall' ladder.

In thef following specication andlclaims," the term protective Wiring willY refer to. all the 'ele ments connectedfin the-circuitof the.protective system, which -is generallyv'afseriescircuit.and inv cludes Window foil lacing, screens, trap doers, andv other Wired units and associated switchn and spring tamper` contacts. l The `term protective wiring asused hereinis alsounderstoodto include all'. equivalent. structures,V such as those used for. protection of. safes, bank Vaults nor Vthe like.

The-alarm unitis formed oa rugged metal housing, its. structural arrangement being shown.

in Figs. 2 to 4. Thealarmhousing consists, in addition .to the -outer housing-structure indicate ed; in Fig. Lanci ofanmterior metal hrung. ci,

insulated ffromthe exterior housing 20.' Inside th'e alarm housing is` mounted. a local nenergy source, such .as aldryfcell battery il, an -alarm device, suchv as avbell. 18, an alarm relay'A with contacts 25,126, a locking relay L With contacts 2l, 28, 29,` B, andf. the .various vWiring.'elements referred.4 to 'hereinafter]l The Valarm",housing lis protected againsttampering by the usualbolt and pry-oitanmer switches indicated schematically at 23.`

The control unit`8 'iis Vformed'of a cabinet usually mounted inthe interior of the guarded prem` ises,..and houses a manually operated on-cit,

test. control switch 59 with contacts SWI, SW2, SW3,SWQ 'and SW, amilliammeter 6| and vari-v ous. ,other elements used. for .controlling and su`` vpervising the proteetivewiring-circuits Which'interconnect through alleadcov'e're'd multiconductorA cable the elementsof the .exterior Yalarmhousing vWith the elementstof the guarded premises. The control unit `lifalsohouses. a. resetting mech- -anismincludinga reset motor -52`Wi-th reset foams 53, 54 and cam controlled contactors CI, C2, C3, C4, C5 for automatically controlling the resetting of the protective system following the oocurrence of an alarm condition as will be explained hereinafter, and a trouble-locating switch arrangement 5| for enabling quick and simple location of the point of the protective system which started the alarm or is defective. In addition, the control unit 8 is provided with a tamper switch 63 arranged to be connected inseries with the protective wiring during the protection on condition so that upon opening the door of the control unit during the protection on condition shall set off the alarm. The trou` ble-locating switch 5I is so arranged in the control cabinet that closure of its cover automatically returns the switch 5I to its off position and thereby restores the normal operative circuits of the protective wiring.

As shown in Fig. 1, the protective system is also provided with a power supply unit 9 which is intended to serve as a principal supply of energy for the protective system, and thus reduce to a minimum the drain of current from the local battery I'f' of the alarm housing 20. In addition, thepower unit I! supplies energy for operating the automatic resetting mechanism, the fault locating arrangement and for other auxiliary service, such as the pilot lamp illumination. The power supply unit may be formed of a transformer 35 having a primary winding connected through fuses 32 to terminals 3U leading to a standard 110 volt A. C. supply line. The transformer 35 has a low voltage transformer winding 35 which supplies through a copper oxidel Fig. 1, the relays and the other elements of the protective system are arranged and designed for operation from a nine volt supply source and the transformer winding 36 with the rectifier 31 and the associated ltering condenser al and series resistors 42, 43 are so arranged and adjusted that normally substantially no current flows into or out of the battery I'I. The transformer winding 35 is, for instance,'designed to deliver an output voltage of about l2 volts and the resistors 42, 43 are dimensioned to maintain across the battery I1 a voltage of about 9 volts, resistor 43 being adjustable so as to adjust the power supply circuit to the condition of current battery drain from the battery. As a result, failure of the external power supply from the power unit 9 does not aiect the operation of the protective system, but under normal conditions the local battery Il serves only as a standby source, and the power supply unit 9 serves as a principal source of energy for the protective system. In addition, the transformer 35 has also a high voltage secondary winding 45 which, as described hereinafter, is used in connection with the trouble locating switch arrangement I Yfor locating trouble points of the protective system, series resistance 45 preventing inadvertent short circuiting of the transformer winding.

The cooperative relationship of the various elements of the protective system will now be described for a normal protection on condition, for instance, when the premises have been closed for the night, and the elements of the system are connected to sound an alarm in case an attempt is made to enter the protected premises or to tamper with the system. In Fig. 1 the heavy line circuit shows the protective wiring connections during the protection on condition, the manual control switch 56 being in the on position and the trouble locating switch 5| in the off position. For the sake of clarity, the auxiliary connections of the protective wiring to the auxiliary power supply unit 9 are not shown in heavy lines, but whenever in the, subsequent description gen- V eral reference is made to the flow of current through the protective wiring, it is understood that the current is normally supplied by the power unit 9 and not by the local battery I1.

In the protection on condition, the alarm relay A is serially connected and energized by current flowing in the protective wiring circuit which may be traced as follows:

From the positive terminal of battery II, through the actuating coil of the alarm bell I8, resistor 22, alarm housing lining 2i alarm housing tamper switches 23, by way of a cable conductor to the closed contacts SWI of the manually controlled switch E@ in the control unit, upper closed contacts TSI of the trouble locating switch 5I, through the wiring conductor 65 of the live protective loop including loop elements I0, II, back through wiring conductor 61, upper closed contacts TS2 cf trouble locating switch 5I, in the control unit, rheostat 1I, milliammeter 6I, control cabinet door tamper contacts E3, upper closed contacts SW3 of control switch 58, through a cable conductor to the actuating coil of the alarm relay A; and continuing therefrom back through a cable conductor to the lower closed contacts SW4 of the control switch 5B in the control unit, wiring conductor B8 of the grounded protective loop including connectors I4, lacings I2, to conductor 69 and ground .'15, and continuing through a grounded conductor 'I passing the control unit, along the grounded cable conductor to the grounded outer alarm housing 2G and therefrom by way of the closed front contacts of the alarmrelay armature 25 to the negative terminal'of the battery I1. In addition, the actuating coil of the locking relay L is energized in parallel with the bell I8 through a circuit leading, from the positive bell terminal connection, by way of fuses I6 through a cable conductor to the closed cam contacts CI of the resetting mechanism in the control unit 8, closed contacts SW2 of the manual control switch 50 back through the cable and the coil of the locking relay L to theother terminal connection of the bell I8.

The alarm relay A, the locking relay L, and the bell I8 and the associated circuits are so designed and proportioned and the current flowing through the protective wiring is so adjusted by the rheostat 1I that under normal protection on. conditions, only the alarm relay A is sumciently energized for keeping its armature front contacts 25 closed while the bell I8 and the locking relay L receive insufficient current for soundingrthe bell or actuating the locking relay L, The milliammeter 6I facilitates the adjustment of the normal protection on current flow condition. In a practical installation, the current ilowing in the wiring under normal protection on conditions is adjusted to 10 milliamperes. With the protection wiring circuit so maintained in the protection on condition, the occurrence of a break or `a cross in the protective wiring of the premises will bring about the de-energization of the alarm relay A in the .alarm housing 2e and instantaneous relaSe of its armature 215 from its normal closed front-contact position to the alarm closed backfcontact 26 position, Inthe closed back-contact position, the armature 25j of the alarm relay connects the bell l5 and the parallel locking relay L circuit directly across the full voltage or the battery i'l, and thereby energizes the bell i8 and the locking relay L with sufdcient current for instantaneously starting the sounding of the alarm bell i8, and for actuating the Vlocking relay contacts 27, 28, 29, 3Q to their front contact positions. Resistor 22 connecting the alarm housing lining 2l to the bell lead is proportioned so as to enable the silencing o f the bell i8 by the key shunt switch 3l when a cross or short circuit occurs between the lining Y2l and the outer housing 2c.

yUnder the protection on conditions described above, the energized position of the locking relay L, establishes at its closed front contacts 21, 28, 29, 3d the following operating circuits:

Its closed front contacts 2 complete a holding circuit for the locking relay L so as to retain its contacts locked in the iront contact position and at the same time maintain itself as well as the bell i8 fully energized for continuously sound.- ing the alarm, even if the fault condition of the protective wiring disappears immediately following its occurrence; its closed iront contacts 28 short circuit the series resistor S3 in the l2 volt rectified power supply circuit so as to draw the electric energy required for sounding the alarm and keeping the locking .relay L in the locked position mainly from the power supply unit 9 and thus preserve the charge of the battery il; its closed front contacts 29 complete a signalling circuit :for leads 3l to the police headquarters for transmitting thereto an alarm; and its closed front contacts energize the reset motor r512 and start the automatic resetting cut-off mechanism which is combined with the control unit 8.

The automatic resetting mechanism comprises the reset motor 52 which drives through a shaft 55 rotary cams ,53, 5d which operate through cam followers 5,6, 57, cam contactors Cl, C2, C3, C4, C5 arranged and operating in the way shown in Fig. 1. The resetting motor 52 may be of the self-starting synchronous type, and, as shown in Fig. l, may he energized from the 12 volt transformer winding '3S so as to rotate the cams, for instance, in clockwise direction, at the rate of one complete revolution per hour. Depending upon the particular requirements, such one revolution vcam cycle may be arranged to have a different period.

Fig. 1 shows the normal protection on position of .the reset cams 53, 5d before the reset vmotor 52 is started by the occurrence of an alarm condition during protection on conditions. The various features of the resetting mechanism of the invention and of its operation are described in my application Serial No. 272,084, iiled vMay 6, 1939, whichhas matured into Patent No. 2,346,171.

In order to `enable an authorized person to enter the protected premises without starting the alarm, there is provided in the entrance ,door to 4the premises .a key Voperated. switch 8;! which in the closed position places a shunt around the part of the live protective wiring loop which includes .the break contacts vof .the main entrance door and other removable attachments, such as windows, .in sucha way that they may be opened without affecting the current dow 4conditions trough the relay-a and die Otter-gera .closed ker shunt Stitch i" tothe. closed 'control switch @Detect Sl/VSiWhlge bri-,Passes the nari of the live protettive ,loop extending from the Side of the positive .bai/terr, through bell 1.8, resistor i 22., alarm .housing lining .2li alarm hoilsng tempore Zt, Control ,Switch contact SWL trouble locating contact 'ESL the live protective loop in.- .cluding the mais .door break @detects iif'bak through the loopl conductor 5,?, milliammeter 6i to the control switch contact Uponclosu-re 0f the key Shu-11i Switch 11 the main, door withits main .door contact break` l5 vas well as theother protective breal; elements included in thelshunted live. D, may be @tenga without winding the @1.33m- 1 l. l. Upon entering Vthe premises, the authorized partygopens the control unit, and operates its main control switch 50, which is usually arranged in the form or a key switch actuable to either the energizing circuit for the Areset motor so as to return the reset mechanism to its starting position shown in the drawings.

4In addition, the control switch 53 establishes in its downwardly shown foff position, a holding circuit for the alarrn relay A leading yfrom the positive battery terminal by way of fuse I'S, resister gli, closed key shunt switch 8l, coil alarm relay A, and the closedcontacts 82, 83 associated with Contact blade SWd, to the negative battery terminal. The 'resistance 8 4 included in this protection off alarm relay holding circuit is so chosen as to energize the relay with its normal holding current, 10 milliamperes, for instance. Relay A remains thus `energized and keeps the ,alarm silent. Negligible energy is con- ,Sumed in this protection oft or daytime condition, and only the power supply circuit 9 delivers the current for the alarm relay circuit.

lIf on arriving ,on the premises, the authorized party finds thealarm'pilot lamp 60 lighted, indieating that an alarm condition existed during the protection on period, he has to locate thecause of the alarm condition and see to it that it Yis removed. The trouble ,locating arrangement combined with the protective system of the invention greatly simplies this task. Y

In the form shown in Fig. l, the 4trouble -looating arrangement utilizes the trouble locating switch 5I and a series of neon lamps, such as 85, 8,5, 27 connected Vat different points of .the Yprotective wiring loops between live vand grounded portions of the loops. Ihe -various Vfeatures of the trouble locating arrangement lof the invention and of :its operation are describedfin my application Serial No. 272,084, Yfiled May 6, 193,9, whichhas matured into PatentiNo. 25.34.6517;-

InFigs- 21110.51 isishgwnthe .Special Q Qnlrugiion and .arrangement of the outdoor .alarm housing unit 1 of the protective system with its outer housing structure 20 and inner insulated lining 2| shown diagrammatically in Fig. 1. The outer housing structure 20 comprises a rectangular strong housing body of metal which has a louvered sound pervious front wall and is secured by long bolts |02 to a anged base wall II I which is firmly clamped to the wall II of the building by the threaded engagement of clamping bolts ||3 `with expansion sleeves I I4 anchored in the building wall I|5, the bottom walls of the housing 20 having holes to allow drainage of any water that may enter. The major part of the space within the housing is occupied by a rectangular battery 'compartment I2I formed of a U-shaped bent sheet metal plate having iianged bottom and top -wall portions which are firmly clamped to the mounting plate III in lthe 'way shown in Fig. 4, so as to support the set of electric supply batteries I1 of the alarm system indicated at I1 in the diagram of Fig. 1. The bolts |02 which clamp the upper flange of the battery compartment I2I to the base wall III hold also clamped thereto bolt brackets |03 terminating at their front ends in solid strong mounting blocks |45 having threaded holes for receiving the bolts |02 which hold the housing 20 clamped to the mounting plate III. Near the ends of the top wall and bottom Wall of the battery compartments are mounted hinge brackets I I6 for hingedly mounting thereon by removable hinge pins hinge ears extending from the adjacent side walls of the alarm housing 20 so that the housing may be swung either to the right or left of the base wall III when the housing is opened.

On a bracket secured to the base wall I I above the battery compartment are assembled the sensitive alarm relay A, the locking relay L and a terminal board with the fuse I6 and terminal clips by means of which the various elements of the protective wiring that are housed in the alarm housing I are interconnected through the multi-conductor lead-cable to the elements of the protective system located on the protected premises. These relays A, L and the other circuit elements are covered by a removable rectangular vcompartment cover |20. In the interior of the hinged housing 20, slightly spaced from its interior walls, is carriedits inner housing or lining `2| so that when the housing 20 is opened on its ihinges, the lining 2| moves with it as a unit to eX- 'pose its interior. As shown in Fig. 4, the lining 12| is insulatingly held within the housing 20 by means of bolts |06, brackets |01 and insulating bushings |08, and spacers |09. The iront face I I0 of the lining 2| is made of a perforated sheet so that the sound generated in the interior of the housing 20 will travel unimpeded to the exterior while preventing tampering with the interior of the housing 20 because any metal object pushed through the louvers will produce a short circuit, or an electric connection, between the outer housing 20 and the inner insulated lining 2'I and start the alarm.

Since the alarm housing 20 is placed high on the building wall and must be serviced from a ladder, it is important to keep its size and volume as small as possible. In the housing arrangement of the invention, extreme compactness of the alarm housing is secured by making the alarm bell or gong in the form of a flat gong plate |30 which is mounted on the iront wall |2| oi the battery casing without substantially taking up any space within the alarm housing 20. As shown in Figs, 3 and 4, the gong plate extends substantially across the whole height and width of the alarm housing unit except for the space in iront of the relay cover |20 which is left free in order to permit inspection and servicing of the relays. In a practical installation, the gong plate |30, nine inches square, formed of a hard brass plate, 1A; inch thick and occupying negligibly little space within the alarm housing, is able to generate as much sound as the very bulky alarm bells mounted over the |bell clapper mechanism of all prior commercial burglar alarm systems. The clapper mechanism I8 for striking the gong plate |30 requires only little space, and as shown, is housed in the small space available within the housing between the lbottom wall of the battery compartment |2| and the insulated inner lining 2 I. In order to produce a large sound energy, the square gong plate is mounted at its 4 antinodal points, namely, the points of minimum or zero vibration when hit by the clapper. These points may be determined by any well-known way. In order to secure efficient sound generation the antinodal points of the gong plate are resiliently clamped between washers |36, |31 of yielding material, such as rubber, by means of screws |35 threadedly engaging holes in the battery plate I2I.

rIhe alarm housing 20 is additionally protected by the usual bolt and pry-oil tampers. As shown in Fig. 4, one such tamper switch |40 is mounted on the base wall III of the housing opposite the end of the housing bolt |02 that upon loosening the bolt, the tamper switch |40 sets off the alarm. The bolts |02 are long and have a ne thread, for instance, 2O threads per inch so that, in the event an attempt is made to tamper and open the housing 20, a substantial time is consumed from the moment the bolt tamper switch I 40 is actuated by the initiation of the bolt unscrewing operation until the bolt has been fully unscrewed from its engagement with the mounting bracket block |45.

In the protective alarm system exemplifying the invention as described above, the batteries which are used as standby power in the event of a failure of the electric power supply circuit, are located in the alarm housing allowing the use of a multi-conductor lead covered cable and eliminatingthe use of costly conduit construction between the part of the system with its control unit that are located on the protected premises and the alarm system elements which are located in the outdoor housing. As a result, it is impossible yto defeat the protection by severing the multi-conductor lead covered cable between the outdoor alarm housing and the control unit located in the protected premises.

A fuse in the outdoor housing is so arranged that the batteries cannot be short-circuited by immersing the severed end oi the cable in mercury or other conducting iiuids.

The outdoor alarm housing in which are located the batteries, the alarm sounding device and the control relays is compact and small, for instance, only 16 inches high, 12 inches wide, and 8 inches deep, and is protected against tampering by bolt and pry-01T tampers. The compact structure of the outdoor alarm housing is made possible by making the sound emitting alarm device in the form of a iiat metal plate having a size of about nine inches square and lbeing only 1/8 of an inch thick.

The insulating housing lining is not mounted in the customary manner, but is insulatingly supported in the outer housing cover and may be removed therewith as a unit. A removable hinge arrangement is provided on the housing so that on proper insertion of the hinge pins, the housing cover may be swung either to the right or to the left on the base wall of the housing which is mounted on the wall of the building and remains stationary when the housing is opened.

The relays and the terminal panel are mounted across the top of the housing hase wall and are protected by a separate removable cover. The alarm relay is arranged for connection by plugging into a iive prong socket which allows the alarm relay to be readily removed or replaced when trouble is experienced with its operation. The locking relay serves not only to lock the alarm circuit, but also for controlling the circuit to the police headquarters, the operation oi thev resetting mechanism, and the special arrangement for raising the supply voltage and supplying the alarm ringing current when the alarm sounding device is actuated to sound the alarm.

The commercial power supply unit is arranged to provide a circuit for supplying a low voltage current for operating the automatic reset motor, the alarm indicating lamp, and maintain the normal protective current in the protective wiring circuit without drain on the battery, and in addition, to supply a current oi a higher voltage of about 70 volts for operating the trouble indicating and locating devices, such as the neon lamps.

An adjustable rheostat is combined with the power supply unit for adjusting the circuit s that substantially no current is either flowing in or out of the standby batteries which are located in the outdoor alarm housing, and a resistor is so combined with the circuit as to prevent the ground of the normally ungrounded protective loop from causing a short-circuit across the higher voltage supply terminals which are used for energizing the indicator devices.

A key control switch which enables the user to set the alarm and leave the premises without sounding the alarm after it is set, is so arrangedk` as to permit testing of the entire protective circuit including the main door tamper switches before the user leaves the premises. In addition, the key control switch is so arranged that an alarm will be sounded if the user attempts to leave the premises and operate the shunt switch before setting the system to its "protection on condition.

The protective wiring circuit and its elements are so arranged that when the protected premises are to be opened, the key control switch is operated to the olf position thereby placing a shunt around the tamper contacts of the main entrance door and the other removable attachments allowing entrance without sounding the alarm. The control unit is then opened and the key switch returned to its on position. If an alarm has occurred during the previous protection on period, the alarm indicating lamp in the control unit would be lighted. When the key switch in the control unit is operated to its oir position it establishes a circuit through the reset motor mechanism causing the motor to return the resetting mechanism to its initial starting position.

In setting up the system, all doors, windows, and other protective devices including the main door are closed and locked. The switch in the control unit is then operated to its test position and a check is made to determine whether the protection on current has its normal value. If no reading is given by the meter, it indicates an improperly closed attachment or a defect or trouble in the wiring. Such trouble or defect may be easily located by the trouble locating arrangement. If the meter reading is proper, the key switch in the control unit is turned to the on position, the key is removed, and the control unit is closed and locked. The door of the premises is then locked, and thereby the shunt switch is moved to the locked protection on position placing the protective system in its operation condition.

It will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specic exemplications thereof Will suggest various other modifications and applications of the same. It is accordingly desired that in construing the breadth of the appended claims they shall not be limited to the specific exemplilcations of the invention described herein.

I claim:

l. In an electrical protective arrangement having a signal controlling protective-wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional power current having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to effect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence. of alarm conditions to limit to a predetermined level the flow of current from said power source and to cause said alarm relay means and said device to be energiZed by said battery in the absence and presence of alarm conditions if current fails to flow from said source; and additional relay means in said circuit system and having switch contacts in said circuit connections and operative during an alarm Vcondition of said system to pass substantially more current to said device from said source than from said battery. f

2. In an electrical protective arrangement having a signal cntrolling protective-wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional vpower current having circuit connections forming partV of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to eiect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence of alarm conditions to limit to a predetermined level the ow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence and presence of alarm conditions if current fails to flow from said source; said circuit connections including means operative in absence of alarm conditionsto limit to a negligible value the flow oi current from said battery; and additional relay means in said circuit system and having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery.

3. In an electrical 'protective arrangement having a signal controlling protective-wiring circuit system: a signal ydevice and a battery in said circuit system; a source of uni-directional power current including alternating current rectifying means having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to effect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence of alarm conditions to limit to a predetermined level the flow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence and presence of alarm conditions if current fails to flow from said source; and additional relay means in said circuit system and having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery.

4. In an electrical protective arrangement having a signal controlling protective-wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional power current including alternating current rectifying means having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to effect operation of said signal device upon occurrence of an alarm condition on-said system; said circuit connections including limit means operative in absence of alarm conditions to limit to a predetermined level the flow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence and presence of alarm conditions if current fails to flow from said source; said circuit connections including means operative in absence of alarm conditions to limit to a negligible value the flow of current from said battery; and additional relay means in said circuit system and having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery.

5. In an electrical protective arrangement having a signal controlling protective-wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional power current having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to effect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence of alarm conditions to limit to a predetermined level the flow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence and presence of alarm conditions if current fails to flow from said source; additional relay means in said circuit system operative upon occurrence of an alarm condition for establishing a locking circuit maintaining said device connected to said battery and said circuit connections irrespective of the operating condition of said alarm relay means; said additional relay means having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery.

6. In an electrical protective arrangement having a signal controlling protective-wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional power current having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to effect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence of alarm conditions to limit to a predetermined level the flow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence and presence oi alarm conditions if current fails to flow from said source; said circuit connections including means operative during normal conditions to limit to a negligible value the ow of current from said battery; additional relay means in said circuit system operative upon occurrence of an alarm condition for establishing a locking circuit maintaining said device connected to said battery and said circuit connections irrespective of the operating condition of said alarm relay means; said additional relay means having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery.

'7. In an electrical protective-wiring alarm arrangement for premises to be protected having a 'gnal controlling protective-Wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional power current having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to effect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence oi alarm conditions to limit to a predetermined level the flow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence or presence of alarm conditions if current fails to flow from said source; additional relay means in said circuit system and having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery; and an auxiliary switch in said circuit system and operable from the exterior of the premises to maintain said iirst relay means energized when in closed position for preventing actuation of said alarm system upon proper entry and leaving of the premises and to cle-energize said rst relay for actuating the alarm system when the auxiliary switch is opened upon leaving the kpremises while the protective system is irnproperly set up.

8. In an electrical protective-wiring alarm arrangement for premises to be protected having a signal controlling protective-wiring circuit system: a signal device and a battery in said circuit system; a source of uni-directional power current having circuit connections forming part of said system; alarm relay means in said circuit system and arranged to be connected to said battery and said source and be maintained energized through said circuit system for holding said signal device inoperative in absence of alarm conditions and to eirect operation of said signal device upon occurrence of an alarm condition on said system; said circuit connections including limit means operative in absence of alarm conditions to limit to a predetermined level the ow of current from said power source and to cause said alarm relay means and said device to be energized by said battery in the absence or presence ofalarm conditions if current fails to flow from said source; additional relay means in said circuit system operative upon occurrence of an alarm condition for establishing a locking circuit maintaining said device connected to said battery and said circuit connections irrespective of the operating conditions of said alarm relay means; said additional relay means having switch contacts in said circuit connections and operative during an alarm condition of said system to pass substantially more current to said device from said source than from said battery; and an auxiliary switch in said circuit system and operable from the exterior of the premises to maintain said rst relay means energized when in closed position for preventing actuation of said alarm system upon proper entry and leaving of the premises and to de-energize said Viirst relay for actuating the alarm system when the auxiliary switch is opened upon leaving the premises While the protective system is improperly set up.

HERBERT M. LAFORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,009,285 Crowley Nov. 21, 1911 1,377,939 Sundel May 10, 1921 1,562,574 Maud Nov. 24, 1924 1,114,565 Williams Oct. 20, 1914 1,365,693 Hess Jan. 18, 1921 1,881,832 Miranda Oct. 11, 1932 819,873 Fawcett May 8, 1906 1,181,419 Williams May 2, 1916 1,238,823 Roeder Sept. 4, 1917 p 1,709,097 Roe Apr. 16, 1929 492,478 Sturts Feb. 28, 1893 1,732,276 Morrison Oct. 22, 1929 2,250,834 Howton July 29, 1941

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