Patent GB-349434-A (GB)
Title: Circuit arrangement for alarm installations
IPC: H04M11/04
Filed: 1929-12-14
Abstract: 349,434. Automatic exchange systems. SIEMENS & HALSKE AKT.- GES., Siemensstadt, Berlin. Dec. 14, 1929, No. 38388. Convention date, Dec. 15, 1928. [Class 40 (iv).] In an alarm system which is described as combined with a telephone system, in which an a arm line leading from an alarm-giving station to a substation is connected with a junction line leading from the substation to the alarm-receiving station by means of a selector in hunting operation, the selector, after an alarm has taken place, may be adjusted from the receiving station by current impulses for the purpose of controlling apparatus at the alarm-giving station. In the arrangement shown, an alarm-giving station T is adapted to be connected for telephone communication to an exchange through lines a, b, a pre-selector VW and a group selector GW. Alarms are transmitted by means of contacts which bring into circuit a rapid interrupter SU or a slow interrupter LU depending upon which contact 5fa, or 4pa, is closed, establishing a circuit through winding I of a differential relay K and contact HU. This circuit may be utilized to drive an auxiliary clock at the alarmgiving station from a main clock at the substation VSt, in which case the contact HU is actuated by the main clock and connects alternatively positive and negative poles of a battery in circuit, the line 8 at the alarm-giving station being connected to the auxiliary clock. If the relay K is unbalanced, either by the interrupter SU or LU being switched in, or by a break or earthing of the line b, the relay operates to complete a circuit through winding I of relay A. Contact 11a then closes, completing a circuit through contact 12t, winding I of relay O, contacts 13r2, 14u, line b1, keys NS, AS, and windings of relays A1, A2 at the alarm-receiving station. The relay O energizes and locks up through its winding II and contact 16o. Relays Al, A2 are also in a circuit from earth through battery and a resistance W, but this resistance is short-circuited through the operation of contacts 18o, 11a. The current through the relays A1, A2 is therefore sufficiently strong to operate relay A1, normally inoperative. Relay A2 is normally operative, but when a break in the alarm line occurs, it is de-energized and causes, through the contact 19a2, the alarm lamp AL to light up. When relay A1 operates it closes contact 20a1 whereby the buzzer W is caused to sound. Contact 21a1 closes to complete a circuit through an impulse sender consisting of a relay I and a retarding relay II. Relay I when energized closes contact 22I to cause the energization of relay II. This relay at contact 23II short-circuits relay I which releases and causes the release of relay II after a short interval. The operation of the relays I, II is repeated while contact 21a1 is closed, so that contact 25II intermittently closes and opens an impulsing circuit through contact 27h1, key AT2, winding I of relay J1, line a1, contacts 29o, 30r2, 31p, and winding I of relay J. Relays J, J1 cause the operation of relays V, V1 which lock up, and operate stepping magnets D, D<1>, whereby the selector W1 at the substation and the selector W1 at the alarm-receiving station are caused to step round synchronously. When the selector W1 reaches the line of the subscriber giving the alarm, relays, P T are energized in a circuit which includes contact 54a, winding I of relay T, contact 55t, switch arm a of selector W1, contact 58u, windings I, II of relay P, and contact 59v. Relay T, which locks up, connects at contact 62t the alarm line to the contact bank of switch arm b. Relay P, which also locks up, opens contact 31p to cause winding I of relay R2 to be energized in the circuit of relays J, J1. These relays J, J1 are inoperative when in series with winding I of relay R2 and therefore release, causing the stepping of selectors W1, W2 to cease. Relays V, VI also release, the relay VI at contact 41v1 closing a circuit to light the lamp StL corresponding to the calling subscriber. Relay VI also acts to energize relay P1, and owing to the energization of relays T, R2, P1 a circuit is completed for the transmission of impulses from the interrupter LU or SU to a winding I of relay R1. This winding operates contact 47r1 in accordance with the impulses of the interrupter, and through contact 47r1, winding II of relay R1 is energized and de-energized accordingly, causing a corresponding actuation of contact 78r1, whereby lamp FL flashes to indicate the nature of the alarm. To restore the system to normal, the operator at the alarm-receiving station actuates the release key having contacts AT1, AT2, AT3. Contact AT3 completes a circuit for relay H1 which locks up at contact 81h1, and at contact 82h1 completes a circuit for winding II of relay J1. This winding is short-circuited by means of contact 63d1 when the rotary magnet D1 has operated, so that the relay J1 and consequently the magnet D1 release. The operation of the relay J1 and the magnet D1 causes the selector W2 to step to normal position. In a somewhat similar manner selector W1 is stepped round, consequent upon the energization of relay U which is deenergized when the selector reaches the normal position. In order to release the relays allocated to the alarm-giving station the operator at the receiving station actuates a release switch AS and by means of a number dial, through which contact 36h is actuated, sends to the substation a number of current impulses which cause the impulsing of relay J and the stepping of selector W1 on to the line which had given the alarm. A circuit is then complete through relay U which at contact 90u connects the line b1 to the alarm-giving station. If now the operator at the receiving station wishes to adjust apparatus at the alarm-giving station, for example, a clock to which the line 8 leads, he actuates switch NS to place potential on the line b1. When the adjustment is finished, the operator presses the release key, contact AT1 of which completes a circuit through winding II of relay R2. This relay operates contact 88r2 to complete a circuit through winding II of relay A. As this winding is wound oppositely to that of winding I of relay A, the relay de-energizes, causing also the de-energization of relay T. Since contact 89r2 is closed, winding III of relay P is energized closing a holding circuit for itself through contact 90p. Contact 105p completes a circuit for winding II of relay J which acts to step the selector Wl to normal position. In the meantime relay V at contact 49v opens the circuit of relay U which at contact 86u opens the circuit of relay R2. The locking circuit for winding III of relay P is opened when the switch arm d of the selector W1 reaches normal position.