US2426085A

US2426085A - Alarm system

Info

Publication number: US2426085A
Application number: US665930A
Authority: US
Inventors: Felix F Denzler
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-04-30
Filing date: 1946-04-30
Publication date: 1947-08-19
Anticipated expiration: 1964-08-19

Description

Aug. 19, 1947. F. F. DENZLER ALARM SYSTEM Filed April so, 1946 2 Sheets-Sheet 1 INVENTOR.

Fsux ,F. Denna:

F. F. DENZLER Aug. 19, 1 947.

ALARM SYSTEM 2 Sheets-Sheet 2 Filed April 50, 1946 THIS 5mm Ar Odd NUMBERED I I I I I l I I I I l E I I Main Loop I l I l I I l l l I I J INVENTOR. FELIX F. DENZLEI2.

fizzorney .IIIIIIIII Patented Aug. 19, 1947 ALARM SYSTEM Felix F. Denzler, Pomona, Calif.

Application April 30, 1946, Serial No. 665,930

17 Claims.

This invention relates to electrical safety devices, such as burglar and fire alarm systems, and has to do more particularly with systems of the type shown in my prior Patent 2,300,409 in which a plurality of sub-stations at difierent locations are connected in series in a common line circuit emanating from a central station.

A broad object of the present invention is to increase the efliciency and utility of an alarm system of the type disclosed in my prior Patent 2,300,409.

A more specific object is to provide an alarm system of the type referred to in which the location of a temporary trouble condition can be determined by tests from the central station even after the trouble condition has corrected itself.

.Another specific object is to provide an alarm system of the type referred to which is extremely difficult, if not impossible, to circumvent and which will indicate the location of an abnormal condition in any part of the system.

Other specific objects and features of the invention will appear from the description to follow with reference to the drawing, in which:

Fig. 1 is a schematic diagram showing the general layout of a system in accordance with the invention, the circuit at the central station being shown in full;

Fig. 2 is a schematic diagram showing the apparatus and circuit at one of the sub-stations;

Fig. 3 is a schematic diagram showing the condition of a portion of the apparatus at a substation under normal conditions when current is flowing in one direction in the line;

Fig. 4 is a schematic diagram similar to Fig. 3 but showing the circuits through the apparatus when no line current is flowing;

Fig. 5 is a schematic diagram similar to Figs. 3 and 4 but showing the circuit condition when current is flowing in direction opposite to the current fiow in Fig. 3; and

Fig. 6 is a detail diagram showing the lock switch of Fig. 2 in day position.

As previously indicated, this system is a further development of the system shown in my Patent 2,300,409, and to simplify comparison of the two systems and an understanding of the improvements introduced in accordance with the present invention, elements of the present system corresponding in general to elements of the system of the prior patent bear the same reference characters.

The complete circuit shown in Fig. 1 shows a system incorporating a central station, which is enclosed within the dotted line 50, and four substations which are identified as ST#1, ST#2,

ST#3 and ST#4. The number of sub-stations may be either less or greater than four, this numher being chosen merely for purpose of illustration. It will be observed that two lines emanate from the central station. One of them, identified as LI, extends to the sub-station ST#1; a second line L2 interconnects sub-station ST#1 and ST#2; a third line L3 interconnects sub-stations ST#2 and ST#3; and a fourth line L4 interconnects sub-stations ST#3 and ST#4. The circuit is completed from sub-station ST#4 back to the central station over a fifth line L5. The details of the apparatus and circuits at the substations will be described later with reference to Figs. 2 through 5.

Central station apparatus The apparatus at the central station includes five relays identified, respectively, as V, LRI, T, LE5 and C. In addition, the central station includes six keys or switches G, R, P, Q, F and E, respectively, resistors 80, 82, BI and 83, a main battery 5!, an auxiliary battery 52, a push button U, an alarm bell 51, a red signal lamp Irrd and an annunciator 54 having a pair of actuating magnets 55 and 56 and a pair of hands 62 and 12.

One terminal of the battery 51 is permanently connected to ground and the other terminal will be hereinafter referred to as battery in accordance with common practice in the signalling art. Normally, battery is connected to .the line LI, and the circuit is shown in heavy lines in Fig. 1. Thus current flows from battery through resistor 82. through resistor 80, through relay LR! thence through relay T and through rela V to line Ll.

The circuit from ground may be traced over contacts l and B of switch F, a test jack 84, thence through

contacts

8 and 9 of switch F through relay LR5 and through contacts 3 and 4 of switch Q to line L5.

Normally a circuit is completed from line Ll to line L5 through the sub-stations, and a current flows to maintain the relays V, LRI and LE5 energized. The line current also flows through relay T, but this is a marginal relay and does not pull on normal line current.

so long as there is no interruption in the current flowing through relays LRI and LRB and the magnitude of the current is insufficient to pull relay T, the alarm relay C remains energized, under which condition the alarm bell 51 and the alarm light Lrd are deenergized. As will appear from the description to follow, any abnormal condition in the system releases the relay C which then completes energizing circuits to the hell 5? and the lamp Lrd from the auxiliary bat- 3 tery 52. By employing the auxiliary battery, actuation of the alarm bell and lamp is assured even though the release of relay C should result from failure of the main battery It Will be observed that the alarm relay C i normally energized from the battery 5|. The circuit may be traced from battery over the contacts I and 2 and through the winding of relay C, thence through the normally closed contacts of relay T, thence through contacts 3 and 4 of relay LRI, thence through contacts 6 and 5 of switch P, thence through contacts 3 and 4 of relay LR5 to ground. Since the circuit includes front contacts of relays LRI and LR5 and back contacts of relay T, relay C must drop in the event of release of either relay LRI or relay LR5 or pulling of relay T.

After having been released, relay C remains down since its circuit is opened at its contacts I and 2. However, if the rest of the circuit is completed up to the relay C, the latter can be operated by pressing the push button U, after which the relay will hold up.

The relay V is permanently connected in series with line LI and functions to indicate flow of current from line LI into the central station under certain test conditions to be described later.

As previously indicated, relay T is a marginal relay which responds to excess current flow to the line to give an alarm by opening its contacts which are in the alarm circuit previously traced.

Relay LRI functions to open the alarm circuit in response to reduction of the current flow to line LI below a predetermined value. It also functions, during a testing operation, to energize the magnet 55 of the indicator 54 over its contacts I and 2 to count sub-stations.

Relay LR5 ftmctions to open the alarm circuit in case of failure of current flow from line L5 into the sub-station. It also functions, during a testing operation, to energize the magnet 56 of the annunciator 54 and count stations.

The resistor 82 is provided for the purpose of adjusting the normal line current to a value such that it will hold relay LRI but Will not pull relay T.

The function of resistor 83 is to adjust the current flowing through relay LR5 under emergency operating conditions, to be described later, to compensate for reduction in line resistance and produce normal current through relay LR5.

Resistors 89 and 8| are provided for the purpose of increasing the current to lines LI and L5, respectively, during operations for resetting the sub-station apparatus which will be described later.

The switch P is provided for the purpose of grounding the circuit between the line relay LRI and the marginal relay T to hold the relay LRI and provide a path from ground from line LI while applying current from the central station to line L5 during testing operations. The switch P when actuated also disables (at its contacts 5 and 6) the alarm circuit previously traced through contacts 3 and 4 of relay LRI and completes an alarm circuit over contacts I and 2 of relay LR5, contacts I and 2 of relay V and over contacts 3 and 2 of switch P to ground.

Switch Q functions. to open the line L5 at its contacts 3 and 4 and to complete an alarm circuit to ground over its contacts 2 and I to contact 5 of relay LRI,

Switch R is provided for the purpose of resetting the sub-stations by the application of current over line LI after the sub-stations have gone down (been de-energized) for any reason. Normally all the contacts are open. When actuated to close its contacts, they perform the following functions:

Contacts I and 2 of switch R complete a circuit from battery over contacts I and 2 of switch G to the contact 2 of relay LRI to permit magnet 55 of the annunciator to be energized in response to operation of relay LRI. Contacts 3 and 4 of switch R complete a shunt circuit through

contacts

4 and 5 of switch G to short out the resistor and increase the current delivered to line LI.

Contacts

5 and 8 shunt out the relay T to prevent its operation in response to the excess current delivered to the line when resistor 80 is shunted out.

Switch G is provided for the purpose of creating an emergency setting to be described in detail later. Th contacts I and 2 are normally closed but when the switch is actuated, they open the circuit to the counting contacts 2 and I of relay LRI to prevent operation of the counting magnet 55. Contacts 3 and 4 are normally closed to permit shorting of the resistor 88 by actuation of the switch R previously described. When switch G is actuated while switch R is also actuated, these contacts 3 and 4 cut the resistor 80 back into the circuit to reduce the line current to its normal value. Contacts 5 and B are normally open but when the switch is actuated they shunt the alarm contacts I and 2 of relay V since the latter relay is used as an alarm relay during emergency set- D.

Switch F is. provided for the purpose of resetting and counting sub-stations over line L5. The different contacts of this switch have the following functions:

Normally open contacts I and 2 are provided to complete a circuit from battery over the normally closed contacts 3 and 4 of switch E to the counting contact 5 of relay LR5 to permit the latter to energize the counting magnet 56. Normally closed contacts 3 and 4 are provided to shunt out the relay T and prevent its operation in response to the excess current applied to line L5 during the counting operation. Normally

open contacts

5 and 5 are for the purpose of applying battery through the contacts I and 2 of switch E, through the test jack 84, through the resistor 83 and through the relay LR5 and the contacts 3 and 4 of switch Q to line L5. Normally closed contacts 6 and I are for the purpose of disconnecting ground from the circuit last traced from contact '1 to line L5. Normally closed

contacts

8 and 9 are for the purpose of removing the shunt from resistor 83 during the counting operation,

Switch E is for the purpose of setting up an emergency circuit over line L5. Its contacts are normally closed. When the switch is actuated, contacts I and 2 are opened to remove the shunt from the resistor BI and reduce the current applied to line L5 to normal value. Contacts 3 and 4 open the circuit from battery (over contacts I and 2 of switch F when the latter is operated) from the counting contact 5 of relay LR5 during emergency setting.

Sub-station apparatus With one exception, which will be noted later, the apparatus at all of the sub-stations is identical. Referring to Fig, 2, each sub-station has a pair of

line terminals

24 and 25, respectively, so arranged in the line circuit that when battery is applied to line LI at the central station, it flows into each sub-station at terminal 24. On the other hand, when battery is applied to line L5 at the central station, it flows into terminal 25 and out of terminal 24 at each sub-station.

The essential elements at each sub-station may be broken down for convenience into a unit A, a unit B, a lock switch N, a day loop DL and a night loop NL, and a ground loop GRL. The loops DL and NL may contain various protective devices, such as door and window switches which are opened in response to abnormal conditions for which the system is intended to give an alarm. The day loop contains switches which are desired for protection twenty-four hours of the day. The night loop contains switches which are desired to protect only at times when the premises are closed. Thus the night loop may contain door switches on doors which are always closed when the premises are not occupied but may be either opened or closed at other times. The ground may simply consist of a wire that is interlaced with the wires constituting the day and night loops to make it more difficult for one to tamper with the day and night loops without introducing ground thereon.

The lock switch N is used to cut the night loop into and out of the alarm circuit, and its operation will be described in detail later.

Each sub-station contains eight relays I, H, M, X, Y, Z, S and K, respectively. Relays I and H are shown in a separate unit A only for convenience of description. These relays have the function of connecting the sub-station circuit to the

line terminals

24 and 25 in one or the other of three different ways, depending upon how current is entering the station. The three possible conditions of the apparatus shown in unit A are illustrated in Figs. 3, 4 and 5.

Fig. 3 shows the condition of unit A under normal line conditions when current is entering the sub-station through terminal 24. It will be observed that a circuit is completed from terminal 24 through a resistor 32, through the relay H directly to a conductor 22; that a second conductor 29 is connected to the conductor 22 within unit A through a resistor 38; and that terminal 25 is connected directly to a conductor 2!. The particular circuit condition shown in Fig. 3 is created by virtue of the fact that current is flowing through relay H and it is pulled, whereas relay I is short circuited by the closed contacts I and 2 of relay H.

The circuit condition shown in Fig. 4 obtains when no current is flowing into the sub-station through either terminal 24 or 25 because under these conditions both the relays H and I are released. It will be observed that conductor 29 is connected directly through relay I to terminal 25 and directly through relay H and resistor 32 to terminal 24, but the conductor 2! is isolated within the unit A. Conductor 22 is always connected to the conductor 28 within the unit by the resistor 39.

Fig. 5 depicts the condition within unit A when current is entering the sub-station through terminal 25. Under this condition relay I is pulled, but relay H is short circuited. Terminal 25 is connected through relay I directly to conductor 22 and through resistor 31] to conductor 22, while conductor 2| is connected through resistor 32 to terminal 24. It will be observed that regardless of the condition of relays I and H, a pair of conductors 26 and 2'! are always connected to opposite ends of the resistor 32.

Unit B contains relays M, X, Y, Z, S and K.

Relay M is a slow release relay that is normally down, but is pulled and released during a reset- 6 ting operation to produce a current interruption that actuates the annunciator 54 at the central station.

Relay X is a slow to operate relay and cooperates with relay M to insure that the latter will be fully saturated before it releases.

Relays Y and Z are slow-release relays and are brought into operation only under certain conditions to be described later. Their function is to introduce a time lag between the resetting of successive sub-stations.

Relay S is a slow release relay that is normally operated but falls down in response to interruption of its operating current for a predetermined interval of time. It cooperates with relay M to produce a counting impulse in the line when the station is reset.

Relay K is a fast action relay which is normally pulled, but falls down in response to any current interruption on the line, to complete a path to ground through resistor 3|, and to out the resistor 32 into the line circuit.

Resistor 30 is provided for the purpose of holding relay H or relay I over a circuit including c0nductor 26 and back contacts of relays S and M to ground when the loop is opened.

Resistor Si is provided to permit relay K to pull if a path for current is provided to the next station over conductor 2!. If the resistor 3| were omitted and contact 4 of relay K were connected directly to ground, no potential would be applied to the winding of relay K, and it would not pull even though there were a path through the relay to ground at the next station.

Resistor 32 is provided in series with the line terminal 24 and is cut into the circuit whenever relay K is down to provide a safety factor against relay M pulling except when the line current is increased by actuating switch R at the central station.

The shunt 33 which is provided at odd numbered stations only is for the purpose of disabling the relays Y and Z only at the odd stations when testing over line L5 from the central station to thereby distinguish between odd and even numbered stations. The operations involving the shunts 33 will be fully described hereinafter.

Operation in response to temporary trouble at sub-station ST#3 As has been previously indicated, current normally flows from battery at the central station out over line Ll. through all the sub-stations and back over line L5 into the central station. The circuit at the central station is indicated in heavy lines.

The normal circuit at a sub-station when the latter is adjusted for night operation is also illustrated in heavy lines in Fig. 2. It will be observed that unit A is in the condition shown in Fig. 5 so that the line current flowing in through terminal 24 is shunted around the resistor 32, over conductors 26 and 2'! through the contacts I and 2 of relay K, through relay H, through

contacts

1 and 8 of relay I, through contacts 3 and 5 of relay H, through conductor 22, through contacts Sand 5 and contacts 2 and I of the lock switch N, through the night loop NL and through the day loop DL and over a conductor 23 into the unit B; thence through contacts I and 2 of relay Y, over contacts 6 and 4 of relay over contacts 8 and l of relay M, through relay S, through relay K, through the contacts I and 2 of relay Z to conductor 2!, and thence 7 through unit A to terminal 25. Hence, relays H. S and K are pulled at all of the sub-stations.

Now assume that a temporary open occurs in one of the loops DL or NL at the sub-station ST#3.

At the central station this interrupts the line current, causin relays LRI and LR to drop, opening the alarm circuit to relay C and causing the latter to release and ring the bell 51 and light the lamp Lrd.

At sub-station ST#1 relay K drops due to the interruption of current, but after dropping, relay K completes a path to ground through relay S over contacts 3 and 4 of relay K and through resistor 3|. This provides a path to ground for relay H. Current is also reapplied through relay S so that it holds. The path is, therefore, still completed through relay K and out through terminal 25 to the next sub-station SK#2. As will be described next, the same operation takes place at sub-station ST#2 so that current is restored through relay K, causing it to pull. Hence, all that happens at sub-station ST#1 is a momentary release and re-pulling of relay K.

At sub-station ST#2, relay K dropped simultaneously with relay K at sub-station ST#1, but when relay K at sub-station ST#2 fell, it provided a path to ground for the re-energization of relay K at sub-station ST#1 and when the latter relay pulled, it took the ground on the line at sub-station ST#1 and applied full current to sub-station ST#2. Relay S held. This left sub-station ST#2 with relays H and S pulled, but with relay K down, because the loop was still open at sub-station ST#3 and there was no path for current to flow to ground at sub-station ST#3.

At sub-station ST#4 all current was cut off b the Opening of the loop at sub-station ST#3 so that relays H and K release at that station.

Because of their slow release characteristics, none of the relays S drop until after the foregoing operations have been completed. However, after an interval, relays S at sub-stations ST#3 and ST#4 do drop.

At sub-station ST#3 the release of relay S completes a direct path to ground from conductor 20 over contacts 2 and I of relay S and contacts 9 and ID of relay M,

contacts

1 and 8 of relay S, and ground loop GRL. At this time, unit A is in the condition shown in Fig. 4, so that there is a path to ground from relay H over conductor 20.

This leaves sub-stations ST#1 and ST#2 in normal condition completing the circuit to ground at sub-station ST#3, and with all the relays down at sub-station ST#4.

Let it be assumed that the temporary opening in the loop at sub-station ST#3 was caused by a burglar opening a door but that the door was closed again immediately after the foregoing operations have occurred,

The reclosing of the loop circuit at sub-station S'I'#3 completes a circuit from conductor 22 through the loop circuit to conductor 23 and through the contacts I and 2 of relay Y, contacts 6 and 5 of relay S, through contacts 1 and 6 of the lock switch N and contacts 9 and ID of relay I, through relay M,

contacts

5 and 4 of relay M, and contacts I and 8 of relay S to ground, but the normal line current is insufficient to pull relay M,

Therefore, the restoration of the loop circuit does not change the positions of any of the relays in the system.

It will be recalled that immediately upon the initial opening of the loop at sub-station ST#3, the line relays LRI and LE5 at the central station released to give an alarm signal. Let it be assumed that after the loop has been restored as described, the operator at the central station responds to the alarm and tests to determine where the trouble condition was. To do this he performs the following operations:

First, the operator at the central station actuates the switch R, which shunts out the resistor 89 and increases the current in the line. This increased current flows through sub-stations ST#1 and ST#2 (which had already automatically restored to normal condition), and through'relay M at sub-station ST#3 to ground, pulling relay M. The pulling of relay M cuts the slow to operate relay X into the circuit. Thus, the current after leaving relay M flows over contacts 5 and 3 of that relay, through relay X and contacts I and, 2 thereof. After a delay, relay X pulls, and this completes a circuit from contact I of relay X to contact 3 thereof and thence over contacts 5 and I of relay M, through relay S and over contacts I and 2 of relay M to ground. Relay S thereupon pulls and shunts relays X and M out by completing a circuit over contacts 6 and 4 of relay S through contacts 6 and I of relay M and through relay S to ground over contacts I and 2 of relay M. After an interval of time, relay M releases, and in releasing, it momentarily opens the circuit while the movable contact 1 is swinging from contact 6 to contact 8. This interrupts the main line circuit through line relay LRI, to actuate the indicator thereat in a manner to be described. When relay M has fully released and its contact 1 is closed on contact 8, the circuit is restored through relay S and through relay K to conductor 2| and thence to sub-station ST#4.

At this time unit A at sub-station ST#4 is in the condition shown in Fig. 4, in which there is a path to ground from terminal 24 through relay H over line .20 and the back contacts of relays S and M to ground so that relay H operates, restoring the condition of unit A to normal, as shown in Fig. 3. Thereupon the apparatus at sub-station ST#4 operates exactly the same as last described in connection with sub-station ST#3 to first pull relay M, then pull relay X, then pull relay S and release relay M to again momentarily interrupt the line current over line LI and leave the relays at the station restored to normal condition.

As has been previously described, up to the time when the operator at the central station actuated the switch R, normal current was flowing from the battery 5| through the resistors 82 and 88 and the relays LRI, T and V out over line Ll to ground through relay M at sub-station ST#3, but the normal line current was insufficient to operate relay M.

When the operator actuated the switch R, it shunted out the resistor and the relay T, increasing the line current to a value sufiicient to pull relay M at sub-station ST#3. At the same time switch R applied battery to the counting contact 2 of the relay LR] and over contact I of the relay to the counting magnet 55 of the annunciator 54 which pulled the latter to step the hand 12 counter-clockwise one space (leaving the hand still one space ahead of the numeral 1 on the annunciator).

When the relay M at sub-station ST#3 pulled, it did not interrupt the line current because at that time relay S was not pulled and the contact I of relay M was not in the line circuit. However, after relay S pulled and released relay M, the contact I of relay M was in the path from the line to ground so that while the contact 1 was moving from contact 6 to contact 8, the line current was momentarily interrupted long enough to let relay LRI at the centnal station fall back momentarily, thereby stepping the hand 12 another space leaving it in front of the numeral 1.

As has already been described, the release of relay M at sub-station ST#3 took the ground off the line at sub-station ST#3 and applied the line current over the line 4 to sub-station ST#4 where it operated the relays in the sequence previously described in connection with substation ST#3 to first pull relay M, then pull relay S and then release relay M to again momentarily interrupt the line current, take the ground off of station ST#4 and complete the circuit through line L5 back into the central station. The interruption of the line current by relay M at substation ST#4 again actuated the counting magnet 55 to step the hand 12 another space into position midway between the

numerals

1 and 2. This indicates to the operator that two stations have been counted and he knows that they represent the number of stations beyond the point where the temporary open occurred. In other words, he know-s that he has counted the number of stations between the point where the open occurred and line L5. Hence, he knows that the temporary open Was on the loop at station ST#3.

It will be noted that if the loop at sub-station ST#3 had been permanently opened instead of temporarily opened, then the circuit would not have been completed through relay M at substation ST#3, and there would have been no current interruption following the closure of switch R at the central station. Hence, the hand 12 would have moved up only one space and stopped. This would have apprised the operator that a trouble condition still existed on the circuit and he would proceed to make a routine test to locate the trouble as follows:

First, he restores switch R. and then actuates switch P. This grounds the heavy line circuit at the central station between relays LRI and T, to hold relay LR! and provide a path to ground from line LI while testing over line L5. It also disables the subsidiary alarm circuit over contaots 3 and 4 of relay LR5 and completes an auxiliary alarm circuit over contacts I and 2 of relay LE5 and the contacts of relay V. Of course, the grounding of the line between relays LR! and V interrupts the flow of current out over line Ll.

The operator then again actuates switch R, again applying battery to the counting contact 2 of relay LRI and stepping the hand 12 another space, leaving it standing to the right of the numeral 1.

The operator then restores switch P, which puts current out on line LI through relay V again and causes the sub-stations to successively interrupt the line current and complete the circuit on to the next station up to the point where the loop is open. All of the stations up to the open are counted at this time because all the relays at the stations were previously released by actuation of switch P. In the present instance, it has been assumed that the loop is open at sub-station ST#3, so only sub-stations ST#1 and ST#2 will interrupt the line current, thereby causing the hand 12 to stop in position midway between the numerals 2 and 3.

The operator next restores switch R and again operates switch P.

The operator then actuates the switch F. This applies battery over' contacts I and 2 of switch E and contacts 5 and 6 of switch F, through the resistor 83 and through the line relay LR5 to line L5. It also applies battery over contacts I and 2 of switch F and contacts 3 and 4 of switch E to the counting magnet 5 of relay LE5, so that when the latter relay pulls, the counting magnet 53 is energized to step the left hand 62 one space into position just to the left of the numeral 4. Thereafter, the sub-stations are successively reset over line L5 up to the point where the open occurred, each station as it resets producing a momentary interruption that drops the line relay LR5 and actuates the magnet 55 to step the hand 62 another space. Since, in the present instance, the open is at sub-station ST#3, the hand 62 steps only one space and is left midway between the numerals 4 land 3. Therefore, the numeral 3 is boxed by the hands 12 and 62, which tells the operator that the trouble condition is at substation ST#3.

It may be noted at this point that if the trouble, instead of being in sub-station ST#3, were in the line between two stations, say between substations ST#2 and ST#3, both of the hands 82 and 12 would have stepped into the same position which, under the conditions described, would be midway between the numerals 2 and 3, because the hand 52 would have been moved twice in response to the interruptions produced by substations ST#4 and ST#3, respectively, and the hand 12 would likewise have been moved two spaces by the two interruptions produced by substations ST#1 and ST#2, respectively. The system, therefore, distinguishes between a trouble condition within a station and a trouble condition on the line between stations.

Emergency setting It is possible with the present system after a trouble condition has developed at one substation to place the system in an emergency setting and cause it to respond to a new trouble condition that may develop at one of the other stations.

At the end of the last operation described, current was feeding into line L5. Then the operator actuates switch R. and restores switch P, after which he switches G and E. This takes battery 01f the counting contact 2 of relay LRI and the counting contact 5 of relay LE5, de-energizing the counting magnets 55 and 56. The actuation of switches G and E also cuts in the resistors and BI, thereby reducing the line current going into both lines LI and L5 to normal value. The oper ator then manually restores the hands 62 and 12 of the annunciator 54 to their normal positions and restores the relay C by pressing the push button U. The system is now in emergency condition and is capable of responding to an alarm condition at any one of the sub-stations ST#1, ST#2 or ST#4, despite the fact that an alarm condition is already eXisting at sub-station ST#3.

If a second open occurs on line Ll, it will release the line relay LR! and release the trouble relay C. Likewise, new open condition on line L5 releases the line relay LRB and releases the trouble relay C.

To locate the new trouble condition the operator restores switches R, G, F and E to their normal positions, thereby causing line relay LE5 to drop, but the line relay LRl holds. The operator then actuates switch P which holds the relay 11 R. b dr s the relairY an the re ays at the sub-statiorisd'n line'Ll. The operator then actuates switch 3. which, as previously described, mo h hand one s ace i The ne o he restores the switch? which causes" the system to] count. the stations in line Ll up to the point of the'new trouble condi on if it is in line Ll. If the new trouble condition is not in line Ll, the"hand 112' is again stepped up into position midway between the numerals 2 and 3 on the annunciator 5Q, advising the operator that the second alarm condition was not created at substation ST#1 or; The operator then actuates switch 'Rcaus hg the system to count the stations on line' L5 up to the second alarm condition thereon. After the location of the second alarm has been determined, the operator again} actuates switches G and El and manually restores. the annunci'ator hands 62 and 12 and presses the push button Ute reset the trouble relay C, thereby. again restoring the system to emergency settinglin which it will respond to a third: trouble condition that may occur on the portions of the lines LI and L5 that are still intact. ltql ttt'ne supewisz'nn ofsystem The p at r at h Qfl lilf l i @3 m a routine checlganddefinitely determine whether or not all 'of'th "sub- 'stations are operative and all of the line sections are intact, including the line sections Ll" n'd Llifwhich are adjacent the central station. This routine check is performed asfollowsz The operator first actuates the switch P to place current on the line between the relays LRI and v: to hold'ife'lay whi e cutting n the current to 'thesub stations (dropping all relays atthesub-stationsl'and'dropping relays V and LR5. The operatonrie'xt "actuatesswitch R to shunt out the relay' T andapply battery to the counting contact 2, of. relay LRI, which causes the hand 12 to step one space. This operation also shunts the resistor -80 to increase the line ur ent The operator than, restores switch P. to. reconnect theline'relayLRl, to the lineLl and apply the heavy or super normal current to the line. aswa ne that an, of the sub-stations are'intact and; that thelines Ll, L2, L3. and L4. are intact, the sub-stations reset in, sequence, moving the hand I? into positioniiust to the right of or head; of, the numeral 4 on the annunciator, thereby. accounting for. all stations. However, this doesnpt establish. that 1ine,L5 isintact from substatiphfi'fik into the central station. The operator then restores switch R. to normal posi- 'tion to out in the resistor, take the shunt ofi relay T and; lie-energize the magnet 55, afterv which he presses the push button U. If the line L5 from substation S'IT#4; is intact, relay LE5 will be pulled and the trouble relay, C will pull over the contacts 3 and 4 of relay LR5 and the contacts {and 4-01, relay LRL Having pulled, the trouble relayc will holdover, its contacts I: and 2, thereby indicating that the entire system is in norma c nd ion.

'lhe ore o n test will detect. any abnormal on iti n n th line.

Supervising switch-over from day to nightf whichtheloc lgv switch N, at. each. sub-station was- 'ihl t 3% ac oss a ofa relay Y. TAt't lieevenInumbered stations, the

shunt 31 m abut' tsff wise -P ?P. m.$d by a pair of contacts {land ill on the relay I, which contacts are closedwhen relay I is de-energized. Relay I is always tie-energized except when the sub-stations areenergized by current transmitted over line' L5 from the central station. During normal operation current flows out from the central station over line Ll to the substations and hence normally the

condutcors

28 and 29 are connected directly to the contacts fi andl of the lock switch at'all stations, either by the contacts 9 and [ll of relay I or bythe shunt 33.

Whenever the

conductors

28 and 29 are shorted, the. relay Y is disabled so that this relay and relay Z remain inactive and play no part in the operation of the circuit.

However, it will be observed that whenever conductors Z8 and 29 are opened exterior of the unit B, the relayY is connected in series with the relay M and the loop circuit. Thus the cir-. cuit can be traced from th loop through QQll-w ductor 23-, through the contacts l and-2 of relay Y, through the contacts 6 and 5 of relay S, thence through relay Y to relay M. When relay Y pulls, it opens itscontacts I and 2, thereby cutting rela Z into the circuit ahead of relay Y. When relay Z pulls, it opens, the contacts I and 2 which are interposed in the conductor 2| leading to the next sub-station. Hence, the circuit cannot be completed to the, next substation (following the energization of relay S and the consequent release of relay M to, give the counting interruption) until relays Y .and Z are released. The circuit over which relays Y and Z are ener-. gized is openedat contacts 5 and fi of relay S when the latter operates, but both Y and Z are slow release relayssothat an appreciable interval of time is introduced between the pulling. ofrelays and the release of relay Z to complet the circuit ontothe neXtsub-station. following the resetting of the instant sub-station.

Ifhe overall effectof the. relaysY and-Z, and the contacts. 5, and 1. of the lock. switch N, is that during a routine supervisory test from the central. station oven lineLLl thehand. 12 of the annunciator 54, moves in rapid steps from a position to the right of the numeral 1 into position, to the right of numeral 4,i-f. thelookswitchesN at all of the sub-stations are in night position. On the other hand, if: all of the lock switches N arein day position, the handf'll at the central station will pause a readily perceptible in.-. terval (which may be inthe neighborhood of two seconds) between each stepping operation. On the other hand, if some of the sub-stations are in i i and thsr-s lbfit ti nsare in petit on h operator a h entral station is apprised by theresultant slow or fast operation of thehand J? at dii ferentportions of; its..travel just whichstationshave been switchedl t- P 3 19; e dawhi h- Sta ion h v not been switched.

khe p w dutaa a tat oa switching from a t g t os t on ma e. a -followsz he operator; at the sub station, inserts a key in the c 5 t e oq be nemthe positiomshown in Fig. 6 during day. operation) and;turnsthe,lock clockwise. The lock is always free to rotate clockwise a distance sufficient to cause contacts I and to ride onto the low portions of cams N4 and N3, but further movement may be limited by engagement of a magnet actuated pawl N6 with a shoulder N59 on the cam N8. The initial movement transfers contact 3 from contact IE to contact 5, opens contacts i and 2 and closes contacts 6 and E. This connects the conductor 22 over contacts 3 and 5 and through the magnet N to the night loop and if the loop is intact, the magnet N28 is energized to release the dog N6 from the shoulder Nii! on cam N9 and permit the operator to rotate the lock through 180 and remove his key. The final rotation of the cam N4 again closes contacts l and 2 to shunt out the magnet N20.

The operation described is usually performed before the operator leaves the premises. Let it be assumed that to leave the premises he has to open a door that is protected by the night loop so that in leaving the premises he sends in an alarm. The operator at the central station then makes his routine test over line Li as previously described. Let it be assumed that the alarm was produced by the operator at substation STt Z leaving the premises so that sub-station ST#2 is in the night position, whereas stations ST#1, ST#3 and ST#4 are still in the day position. The operator at the central station will be apprised of this fact by the action of the annunciator hand 72. Thus this hand, after stepping into position ahead of the numeral 1 in response to the interruption of current produced by relay M at sub-station STitl, will pause before stepping across the numeral 1 because the relays Y and Z 1 at sub-station S'Iail will introduce an additional time delay before the circuit is completed from sub-station ST#l to sub-station ST#2. This tells the operator at the central station that substation ST#1 is still in the day position. However, after stepping across the numeral 1 in response to the current interruption produced by relay M at sub-station ST#2, the hand 12 will step rapidly across the numeral 2, thereby telling the operator at the central station that sub-station ST#2 is in the night position.

Following the operation at sub-station ST#3, there is a pause before the hand 72 steps across the numeral 3 indicating that sub-station ST#3 is still in day position. Since the hand moved into position between the numerals 3 and 4 in response to the interruption produced by the resetting of station STit l, it will remain in that position. However, the operator is apprised as to whether or not sub-station ST#4 is in day or night position by the time required for relay LE5 in the central station to pull following the movement of the hand I2 into position between the numerals 3 and 4. He obtains an indication of the time when relay LE5 pulls by holding the push button U down so that the lamp Lrd goes out in response to the pulling of relay LE5.

As each sub-station is switched from day to night position, the circuit will be interrupted as described and the operator at the central station will perform his routine test so that he can keep a record of the time at which each sub-station was switched into night position.

To switch the sub-stations from night position into day position, it is simply necessary for the operator at the sub-station to insert his key in the lock N5 and rotate it counter-clockwise 180 back into the position shown in Fig. 6. The lock dog N6 does not function during this operation because the night loop is being cut out of 14 the circuit and there is no occasion for testing to see that the loop is intact.

Location of sub-station completely removed from circuit The provision of the shunts 33 at alternate stations (the odd numbered stations in this instance) enables the operator at the central station to determine the location of a sub-station that might be completely removed from the line, as by shunting. Thus let it be assumed that the present invention is incorporated in a burglar alarm system and that a clever burglar, prior to burglarizing the premises at sub-station ST#3, placed a shunt between lines L3 and L5 and cut sub-station ST#3 completely out of the circuit.

A routine test made over line L! would apprise the operator at the central station that one of the sub-stations had been cut out of the line because impulses to actuate the hand 72 of the annunciator would be received from only the three remaining stations. However, this routine test would not inform the operator which station had been removed from the circuit. The operator can determine the location of the missing station by making his routine test over line L5 in the manner previously described.

Thus, whereas when testing over line Ll the relays H at the sub-stations are energized, the relays I remain de-energized and therefore the contacts 9 and lo on the relays I remain closed and the relays Y are shunted out at all stations. On the other hand, when the test is made by applying current to line L5, the relays I are energized instead of the relays H, and the energization of the relays I at the even numbered substations opens the shunt around the relays Y at those stations, permitting them to operate and introduce a time delay.

Hence, when testing over line L5, sub-station STit, after delivering its impulse to actuate the hand 62 into position to the right of the numeral 4, does not complete the circuit rapidly to line L4 because relay I opened the shunt and out in relay Y, which, in turn, out in relay Z, which opened the contacts I and 2. This held the circuit at station ST#4 for a predetermined interval.

The operator at the central station, therefore, gets a normal movement of the hand 52 in response to the impulse from sub-station ST#4. However, since sub-station ST#3 is cut out of the circuit, the resetting of station ST#4= completes the circuit onto sub-station ST#2, and the transmission of the impulse from sub-station ST#2 is delayed by virtue of the fact that the open contacts 9 and H] of relay I at sub-station ST#4 caused the operation of the relays Y and Z at that station. Following the transmission of the impulse from sub-station ST#2, the connection to sub-station ST#1 is also delayed because there is no shunt 33 at station ST#2. Hence, the operator gets a delayed movement of the hand 52 in response to the current interruption at substation ST#1.

If sub-station ST#3 had not been cut out of the circuit, the operator at the central station would have obtained a normal movement of the hand 52 in response to the current interruption from sub-station ST#4; a delayed movement of the hand from the current interruption at substation ST#3; a normal movement of the hand from the interruption at sub-station ST#2; and a delayed movement of the hand from the interruption at sub-station ST#1. The fact that both the second and third movements of the hand were delayed, tells him that it is sub-station ST#3 that has been removed from the circuit.

As another example, let it be assumed that station ST#2 is cut out of the circuit. The operator at the central station when testing over line L will then get a'normalmovement of hand 62 from station ST#4; he will get a delayed movement of the hand from station ST#3; and he will get a normal movement of the hand from station ST#1. Thisoperation is sufiicient to apprise him of the fact that station S'I-#2 is the one that has been removed from the circuit.

As a further example, let it be assumed that station ST#1 is removed from the circuit. In response to a test over line L5 the operator at the central station will obtain: normal movement of the hand in response to the current interruption from station ST#4; a delayed movement of the hand in response to the interruption from station ST#3; and a normal movement of the hand in response to the interruption from station ST#2. It will be observed that this indication is the same as that that was obtained when station ST#2 was the one that was removed from the circuit. To distinguish between the two situations, the operator observes the further action of the system after the last station still in the circuit has been reset. Thus following the resetting of the last station, the current enters the central station on line LI and flows through relay V to ground at contact I on switch P. Relay V thereupon pulls, closing a circuit to ground from the switch P over the contacts I and 2 of relay LR2 and contacts I and 2 of relay T through relay C and push button U (which the operator is holding closed) to battery, thereby pulling relay C to extinguish the red light Lrd.

If station ST#2 was the one that was removed from the circuit, the red light is extinguished quickly followin the last movement of the hand 62. On the other hand, if station ST#1 was the one that was removed from the circuit, a time delay occurs before the red light Lrd is extinguished.

Miscellaneous details It will be observed that contacts 2 and 3 of relay S at eachsub-station short circuit the resistor 30 when relay S is pulled. The purpose of this is to stabilize the line current during the interval that the sub-stations are impulsing.

Various values of potential and resistances may be employed in the system, depending upon various' factors, including the number of sub-stations to be actuated. However, in a typical system employing four sub-stations, elements having the following values may be employed, where the potential of source 5| is 60 volts and the nominal normal line current is 15 milliamperes.

As has been previously indicated, the resistors 32 at the sub-stations are cut in only when the relays K are down and are to keep the current fairly constant during the resetting operation only. These resistors 32 preferably have difierent values at different stations. Thus, at station S'I-#l, resistor 32 may have a value of 800 ohms; at station ST#2 it may have a value of 400 ohms; at station S'I#3 it may have a value of 200 ohms; and at station ST#4 it may be entirely omitted or have a value of zero ohms.

Various departures may be made from the exact construction shown and described without departing from the invention which is to be limited only to the extent set forth in the appended claims.

I claim:

1. A signaling system comprising a central station, a line circuit, a plurality of sub-stations connected in series in said line circuit, and a common current path between all said stations, in which said central station includes means for selectively supplying either a normal current or a super-normal current to one end of said line, and counting means for counting interruptions in current flow to said line, and in which at least one of said sub-stations includes: a normally closed protective loop; first means responsive to flow of current through said loop into said line circuit for maintaining said sub-station in a normal condition in which said loop is connected in series in said line, and responsive to interruption of current through said loop for connecting the loop between said one end of the line and said common path; and second means responsive to prolonged interruption of current from said loop followed by flow of super-normal current from said loop for momentarily interrupting current flow from the central station to that substation and then restoring said sub-station to normal condition.

2. A system as described in claim 1 in which said second means comprises first and second slow release relays, said first relay being in series with said loop and normally energized over its own holding contacts and when de-energized connecting said second relay between said loop and said common path, said second relay being responsive only to super-normal current and when energized connecting said first relay between said loop and said common path to energize said first relay and thereby de-energize said second relay, and contact means on said second relay formomentarily interrupting current flow into said substation during release of said second relay.

3. A system as described in claim 1 in which said second means comprises first and second slow release relays and a third slow-to-operate relay; said first relay being normally in series with said loop andenergized over its own holding contacts and when de-energized connecting said second relay between said loop and said common path; said second relay being responsive only to super-normal current and when energized con- 4. A system as described in claim 1 including adjustable resistor means at said central station in series with said current supply means and said one end of said line.

5. A system as described in claim 1 in which at least one of said sub-stations includes a resistance element in the circuit between said one end of said line and said second means, and the said first means includes means for shunting said resistance element only while said one sub-station is maintained in said normal condition.

6. A signaling system comprising a central station, a line circuit, a plurality of sub-stations connected in series in said line circuit, and a common current path between all said stations, in which said central station includes means for selectively supplying either a normal current or a super-normal current to one end of said line, and counting means for counting interruptions in current flow to said line, and in which at least one of said sub-stations includes: relay means responsive to current flow from the substation into the line for normally maintaining the sub-station connected in series in the line, said relay means being responsive to current interruption to establish connection to said common path at that sub-station, and including means responsive only to fiow of said super-normal current through that sub-station to said common path for momentarily interrupting said super-normal flow and restoring that sub-station to normal condition.

'7. A signaling system comprising a central station, a line circuit having two ends entering said central station, a plurality of sub-stations connected in series in said line circuit and a common current path between all said stations in which said sub-stations each include: switching means operable in response to current flow through that sub-station from either adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section; said central station including a source of current having one terminal connected to said common path, first and second line relays, and a resistor, switching means for selectively either connecting said first line relay between the other terminal of said source and one end of said line and connecting the second line relay between said one terminal of said source and the other end of said line, or connecting said second line relay and said resistor in series between said other terminal of said source and said other end of said line.

8. A signaling system comprising a central stasection to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section, at least one of said substations including means for introducin a time delay between current interruptions produced by a pair of successive sub-stations.

9. A signaling system comprising a central station, a line circuit, a plurality of sub-stations connected in series in said line circuit and a common current path between all said stations, in which said central station includes means for applying potential between said common path and one end of said line, and means for counting interruptions in current fiow to said line, and in Which said sub-stations each include: switching means operable in response to current flow through said sub-station from one adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section, at least one of said sub-stations including means for introducing a time delay between the momentary interruption of current flow and the switching of said current from said common path into the other adjacent line section.

10. A signaling system comprising a central station, a line circuit, a plurality of sub-stations connected in series in said line circuit and a common current path between all said stations, in which said central station includes means for applying potential between said common path and one end of said line, and means for counting interruptions in current flow to said line, and in which said sub-stations each include: switching means operable in response to current flow through said sub-station from one adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section, at least one of said sub-stations including slow action relay means having contacts in the circuit to the said other adjacent line section and actuated under control of said switching means for delaying application of current to said other adjacent line section following said momentary interruption.

11. A signaling system comprising a central station, a line circuit, a plurality of sub-stations connected in series in said line circuit, and a common current path between all said stations, in which said central station includes means for applying potential between said common current path and one end of said line, and means for counting interruptions in current flow to said line, and in which said sub-stations each include switching means operable in response to current flow through said sub-station from on adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section; at least one of said sub-stations also including a pair of normally closed protective loops and loop switching means operable into two positions for selectively either connecting one loop only or connecting both loops in series with said one adjacent line section, said one sub-station also including means for introducing a time delay between the interruption produced at that sub-station and the interruption produced at a next adjacent sub-station, and

means for rendering said time delay means operative in one position of said loop switching means and inoperative in the other position thereof.

12. A signaling system comprising a central station, a line circuit, a plurality of sub-stations connected in series in said line circuit, and a common current path between all said stations, in which said central station includes means for applying potentia1 between said common path and one end of said line, and means for counting interruptions in current flow to said line, and in which said sub-stations each include: switching means operable in response to current flow through that sub-station from one adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section, one set of alternate substations each including means for introducing a time delay adjacent the momentary interruption produced at that sub-station.

13. A signaling system comprising a central station, a line circuit having two ends entering said central station, a plurality of sub-stations connected in series in said line circuit, and a common current path between all said stations, in which said central station includes means for selectively applying potential between said common path and ither end of said line, and means for counting interruptions in current flow to said line; and in which said sub-stations each include switching means operable in response to current flow through that sub-station from either adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section; at least one of said sub-stations including means for introducing a time delay between successive current interruptions; and time delay control mean at said one sub-station selectively responsive to the entry of current from opposite ends of said line, whereby said time delay means functions in response to current from one end of said line but not in response to current from the other end of the line.

14. A signaling system comprising a central station, a line circuit having two ends entering said central station, a plurality of sub-stations connected in series in said line circuit and a common current path between all said stations, in which said central station includes means for selectively applying potential between said common path and either end of said line, and means for counting interruptions in current flow to said line; said sub-stations each including switching means operable in response to current flow through that sub-station from either adjacent line section to said common path for momentarily interrupting said current flow and switching said current from said common path into the other adjacent line section; at least one of said sub-stations including a pair of normally closed protective loops and loop switching means operabl into two positions for selectively either connecting one loop only or connecting both loops in series with an adjacent line section, said one substation also including means for introducing a time delay between the interruption produced at that sub-station and the switching of said current from said common path into the other adjacent line section; and means for rendering said time delay means operative in response to positioning of said loop switching means in one only of said two positions and entry of line current into 20 that sub-station from one only of the two adjacent line sections.

15. A system as described in claim 12 including means at said central station for indicating current flow from the other end of said line into said central station.

16. A signaling system comprising a central station, a line circuit having two ends entering said central station, a plurality of sub-stations connected in series in said line circuit, and a com mon current path between all said stations, in which said central station includes means for selectively applying potential between said common path and either end of said line, and means for counting interruptions in current flow t said line; and in which said sub-stations each include switching means operable in response to current flow through that sub-station from either adjacen-t line section to said common path for momentarily interrupting said current flow and switchin said current from said common path into the other adjacent line section; means for introducing a time delay between successive current interruptions; and time delay control means at one set of alternate sub-stations for selective rendering said time delay means inoperative in response to entry of current from one end of said line and operative in response to entry of current from the other end of said line.

17. A signaling system comprising a central station, a line circuit having two ends entering said central station, a plurality of sub-stations connected in series in said line circuit, and a common current path between all said stations, in which said central station includes means for selectively applying potential between said common path and either end of said line, and means for counting interruptions in current flow to said line; and in which said sub-stations each include switching means operable in response to current flow through that sub-station from either adjacent line section to said common path for m0- mentarily interrupting said current fiow and switching said current from said common path into the other adjacent line section; means for introducing a time delay between successive current interruptions; time delay control means at one set of alternate sub-stations for selectively rendering the time delay means at those sub-stations either operative or inoperative independently of the end of the line from which current enters those sub-stations; and time delay control means at the other set of alternate sub-stations for selectivel rendering the time delay means at those sub-stations either operative or inoperative in response to current entering from one end of said line, and rendering the time delay means inoperative in response to current entering from the other end of the line.

FELIX F. DENZLER.

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

UNITED STATES PATENTS Number Name Date 967,633 Goldstein Aug, 16, 1910 2,220,371 Hopkins Nov. 5, 1940 2,234,940 Hopkins Mar, 11, 1941 2,157,864 Phinney 1- May 9, 1939