Patent GB-302678-A (GB)
IPC: H04M11/04
Filed: 1928-07-04
Abstract: 302,678. Siemens & Halske Akt.- Ges. Dec. 20, 1927, [Convention date]. Fire, police, and like alarm systems.-In an automatic telephone system in which the occurrence of a fire or burglary at a sub-station causes a distinctive signal, fast or slow impulses, to be transmitted over the subscriber's telephone line, the signal causes the line, to be extended over tandem no-normal call-finders to the fire or police station to which the subscriber's number is then automatically transmitted to operate a lamp indicator. The number is re-transmitted from the indicator position to a distant point or a recording apparatus. First call finder. A clock connected to 8 at the substation normally receives control impulses from 7uk over winding I of a differential relay K the other winding of which receives the impulses in a local circuit. Burglar and fire contacts connect up slow and fast interrupters LU, SU respectively in place of the clock, unbalancing K which energizes A which locks over its lower winding and energizes the group starting relay An1, to energize R1 in the first idle call finder. R1 energizes the stepping magnet D1 which short-circuits R1 and the finder steps automatically until wiper b1 finds the calling substation, whereupon P1 pulls up in series with Y (upper) and extends the start-wire to the next finder. Y cuts T into its circuit and T inserts Y releases An1, and leaves A locked over an enquiry key contact 28 AbT. Discrimination between two kinds of alarm. 2nd finder. The impulses from LU or SU now operate J which repeats them to V1 which is short-circuited between impulses to cause it to follow the slow burglar impulses, but to remain steadily energized by the quick fire impulses. On the first relapse of J, X pulls up and locks itself. If VI falls back, U pulls up, locks itself, starts a second call finder of the group (not shown) leading to the police station and marks the first finder calling by connecting relay T1 to the corresponding test terminal. If V1 remains energized, F pulls up on the relapse of Y1 (which was energized by PI and falls sluggishly when short-circuited by X), marks the finder calling to the fire-station group of second finders and starts one of them by energizing An2. B being normally energized, R2 pulls up and interacts with the magnet D3. When the calling finder is found, switching relay P3 pulls up in series with T1, cuts off B to stop the finder and extend the starting circuit, and short-circuits its lower winding. The circuits may be modified to extend a connection to a police and fire station simultaneously, in case of a fire alarm. Transmitting calling number. T1 on pulling up in series with P3, cuts off X and energizes R1 which interacts with D2 to drive the impulsesending switch ZG, and at the same time sends impulses over 75p2, to relay J2 which repeats them over the wire 108. V2 remains up during impulses and disconnects the incoming a-wire. When the wiper 12 reaches the terminal permanently marked in accordance with the first digit, P2 pulls up, opens the circuit to J2 and locks itself. The sender then moves idly until wiper 12 reaches a terminal connected to X(I) whereupon X short-circuits Y1 which releases X and unlocks P2 to cause impulse transmission to be resumed. The second and third digits are terminated by temporary marking over the wipers c1, d1 of the first finder. When the sender reaches the end of its bank, X is energized in series with Z(III). Z locks up in series with P1 and cuts off Y which with Z extends a speech circuit from the subscriber through the call fnders. A, K and T remain energized. Receiving number. J3 at the fire &c. station repeats the number to digit registers W1, W2, W3. A dialling relay V3 in the pause following the digits energizes H3. Z3 to connect up the next register and after the final digit energizes E3 which energizes U3 which lights a calling lamp Al3 and energizes a thermal relay Th3 which. after an interval, gives an alarm. The attendant then throws key Ab which extends the talking to a supervisor's desk and energizes A3 to cause a lamp indicator to display the number on the registers. Re-transmitting number to a substation or recorder. A3 also energizes ZA3 to start the sender ZG4 and mark the number in its bank. ZA3 locks up, short-circuiting its lower winding. The sender operates in the same way as that described above, R3 interacting with the stepping magnet D4 and sending impulses over 61, P3 stopping each digit when wiper 41 reaches the marked terminals, and X3 starting the next one by short-circuiting Y3 to release P3. At the end of the number, ZG4 proceeds to, and remains on, its last terminals, Z4 locks up and energizes 0. If it is necessary to send the number a second time, 97T is pressed to cause the sender to step to its first terminals. Relays O and Z4 fall back and Q energizes and locks since 0 is slow to release, but AR remains inert since, the heavy armature 102q does not pull up until O has released. Restoring apparatus to normal. When the sender arrives at its last contacts a second time, Z4 and O operate again, but AR now pulls up, holds over 60b3, and cuts off B3 whereupon ZA3, Q and AR fall back. The sender steps, to normal and 0, Z fall back. If this number is not sent a second time, AT is pressed to operate AR. Assuming the key Ab has been restored, the relapse of ZA3 energizes L3 which unlocks A3, grounds the wire 107 to energize the reverse winding II of Z and cause its relapse, shortcircuits U3 which removes the ground connection, and energizes Dh, Dg, De, which interact with the stepping magnets to restore the registers. On the relapse of Z, the circuits of the first finder are normalized by the relapse of J, X, Y1, F, U, V1, P2, and T1. When the registers are all home, N3 pulls up and connects battery to the wire 107 to re-energize B and make the 2nd finder selectable again. The individual relays A, K, T remain energized until released by the subscriber or an attendant. Line faults. A disconnection or ground fault on the b-wire unbalances K as in the case of a burglary &c., but when the first finder switches through, J remains back or is permanently energized and one of the lamps L1, L2 glows steadily. Apparatus faults. Thermal relays Th1, Th2 in the finder starting, circuits energize alarm relays Al1, Al2 if the finders fail to operate correctly.