Patent GB-280919-A (GB)
IPC: G08B25/00
Filed: 1927-11-15
Abstract: 280,919. Siemens & Halske Akt.-Ges. Nov. 16, 1926, [Convention date]. Fire-alarm systems.-In a signalling system, more particularly for fire alarm purposes, signals indicating the number of a calling point are received by two or more selectors which each control lamp indicators. The arrangement is such that with a single signal only one selector is effective while signals made simultaneously or in rapid succession are transmitted independently to separate selectors. Fig. 1 shows a closed loop with alarms M1, M2, and normally energized line relays A, B. In the event of a single call slow release relays G, H are energized and impulse relays N, 0, transmit the signal to selectors WI, WII. A prolonged terminating impulse operates a slow to attract relay V1, which energizes relays S, Q and thus the heavy current relay ST which connects the selector WI and the indicator selected to the power supply. Meanwhile the operation of relay S energizes a return relay RII for selector WII which interacting with the auxiliary return relay RWII is returned to normal thereby de-energizing relays RII, RWII. The system is returned to normal by a return key U, which energizes a return relay which with its auxiliary relay effects the return of the selector WI to normal. A further call before the operation of key U causes impulse relays N, O, Fig. 2, to control selectors WIII, WII, the operation of relay Q opening the circuit of selector WI and connecting selector WIII, in its place through the contact y2. The terminating impulse operates relay V1 which energizes relays S, QY. Relay Q operates the indicator selected by selector WIII and effects the return to normal of selector WII while relay Y on the release of relay S at the conclusion of the signal operates a locking relay P. A similar relay Z associated with selector WI is operated and these relays remain energized until the restoration of the system to normal by the return key U is effected and prevent the operation of relay VI by the terminating impulse of a later signal from returning the operated selectors to normal. A third call will affect selector WII only through impulse relays N, O in parallel, which through relay X also controls the indicators. In the event of the simultaneous operation of two calls, M1, M2, as illustrated in Fig. 3, both selectors WI, WII will be operated while the impulses coincide. If M1 is the first to terminate its long terminating impulse will hold relay A energized so that differential relay FI and relay K are energized so that the further impulses from call M2 to relav O will further advance selector WII. During these further impulses through relay B relays A, N are energized so that differential relay FII and locking relay L and the slow to operate relay V1 are energized but the operation of relay L causes relay T to operate and lock itself and de-energize relay VI and thus relays FII, L are de-energized. The terminating impulse of the call M2 will again operate relay V1 which connects the indicator as with the single call operation. A second call M2 in rapid succession as illustrated in Fig. 4 causes relay A or relay B to be de-energized and through contacts a2, g3 relay VII is energized and operates the return relay RII so that selector WII is returned before the impulses of the second drum are received.