Patent GB-281173-A (GB)
Title: Improvements relating to repeaters for electric signalling circuits
IPC: G08B25/00
Filed: 1926-05-28
Abstract: 281,173. Imray, O. Y., (Gamewell Co.). May 28, 1926. Fire and like alarm systems.-Relates to electric signalling systems, particularly for fire alarm purposes, of the kind in which a number of extended signal-initiating and/or alarm lines enter a central station, and comprises improve,- ments in the repeating or relaying apparatus by which signals formulated in one of the lines are repeated over the whole, or selected portions, of the signalling system. The repeating apparatus is built up of a number of panels, one for each line. The panels being interconnected by busbar connections are capable of extension as new 'lines are added and of easy replacement when faulty. Different types of panels are used according as the corresponding line is of the normallyclosed or normaly-open type. The repeater may also comprise a spring-driven rotary contact drum tripped at the beginning of a signal impulse and making one complete revolution for each impulse. A retarded contact device associated with the rotary drum is arranged to hold its contacts open until the completion of the train of impulses constituting a signal. The repeating system is designel to prevent interference between signals concurrently initiated in different lines as effectively as the known non-interference transmitters function when connected in the same line. The repeater remains under the control of the line that first begins to transmit its signal, any second signal formulated in another line during the transmission of the first signal being localized to that other line. Moreover the repeater does not respond to any overlapping residue of the second signal. The system shown in Fig. 1 comprises three panel units 101 - - 103 associated with three signal-initiating and alarm circuits A, B, C of which A and B are of the normally-closed type, and C of the normally-open or weak test current type. Two other lines D, E are alarm circuits only, one of each type. Each unit panel comprises four relays A1 - - A4, B1 - - B4, &c. The relays A1, B1 &c. are for the purpose of locking the circuits, so as to render the mechanism unresponsive to all but the initiating circuit at the moment in control. Relays A2, B2, &c. are operated by signals coming in from the lines amd serve to set in motion the rotary contact device F. Relays A3, H3, &c. are circuit-relays for rendering the repeater responsive to other initiating circuits during abnormal conditioning of the originating mechanism of any circuit. Relays A4, B4, &c. are make and break relays for formulating signals in their associated circuits. Fig. 7 shows in detail the circuits of the A panel 101, and the rotary device F, and Fig. 8 shows the circuits of a C panel 103. Signal initiated on a normally-closed circuit. Assuming that a signal originates in the circuit A, the first current interruption at the transmitter A5 sounds the bells A6 and releases the relay A2, causig its armature 131 to engage contact 133 and so complete a circuit for the battery F7 through a magnet 164. This releases a detent 167 and allows the drum 168 to make a clockwise revolution, during which its contacts engage brushes 170 - - 178 in a predetermined order; also a cam 184 engages a lever 185, thus allowing spring contacts 195, 196 to close. The lever 185, is slowly returned by a spring 194, being retarded by the ratchet-driven escapement 192. The brushes 174 - - 178 serve to repeat the signal in the alarm circuits D and E. The brushes 170, 171 on engaging contact 179 energize the relays A4, B4, C4 in series from the local battery F7, lifting the armatures to contacts 163. For the B circuit this results in a short-circuit of the contacts 119, 120 of the locking-relay B1, so that a subsequent energization of the relay B1 does not affect the alarm bells B6 nor the relay B2. The engagement of contacts 195, 196 then energizes the locking-relays B1 and C1 but not A1. The locking-relays B1, C1 when once energized close holding-circuits at contacts 113, 114 and remain energized so long as contacts 195, 196 are in engagement. The relay B1 opens the contacts 119, 120 as referred to above, whilst the relay C1 closes contacts 123, 125 and establishes a current path from the line circuit C through the relay C2 and the bells C6. Also the "fault " bell 204 will be sounded. Towards the end of the rotation of the drum 168 the brushes 172, 173 are bridged by the contact 180, causing energization of the restoring-relay A3, but not energizing the relays B3, C3. The restoring-relay armature 150 engages a contact 151 and closes a holding-circuit, which includes contacts 116, 117 of the unenergized locking- relay A1, and contacts 136, 137 of the de-energized line-circuit, relay A2, so that relay A3 remains energized when contact plate 180 moves away from the brushes 172, 173. The lifting of the armature 150 opens contact 152, thereby deenergizing the magnet 164 and releasing the detent 166 from the arm 169 on the drum 168. During the small subsequent movement of the drum, the circuit of the make-and-break relays A4, B4, C4 is opened at the brushes 170, 171, thus interrupting the current flow in the circuits B, C de-energizing bell magnets B6, C6 and ring- ing the bells B6. At the termination of the first signal impulse (when circuit A is again closed by the transmitter) relay A2 is energized, opening contacts 136, 137 and releasing the restoring- relay A3. Succeeding signal impulses from the transmitter in the line circuit A develop a similar cycle of operations and operate the bell signals in all the circuits A - - E. Throughout the complete signal, the holding-current path for relays B1, C1 is maintained by the engagement of contacts 195, 196, as the retarding-device 192 does not allow these contacts to open before the next signal impulse arrives. Interference by transmitters in the lines B, C is thus prevented. Upon completion of the signal, the contacts 195, 196 open, and the locking-relays B1, 01 are released, and the normal current paths for the circuits B, C are re-established. Should signal transmitters A5, B5 in the circuits A, B be operated simultaneously, the operation proceeds as above-described so long as the impulses synchronize. If, however, in the sequence of impulses, circuit B is broken whilst circuit A remains closed, the control of the circuit A is surrendered to the repeater A4, and all the alarms will respond to the transmitter B5. If transmitter A5 is equipped with " succession " mechanism, its signal will be formulated at the conclusion of the B5 signal. Signal initiated in normally-open line (or line carrying weak test current). When the circuit is closed at a transmitter C5, the resistance and fault relay are cut out, causing the alarm bells C6, and the fault bell to ring, and energizing the relay C2 through the contacts 123, 124 of the locking-relay C1. By closing contacts 131, 132 the magnet 164 is energized and releases the drum 168, which in its rotation energizes the make-and-break relays A4, B4, C4 and the locking relays A1, B1. When the brushes 172, 173 are bridged by the plate 180, the restoring-relay C3 is energized from battery F7 through a circuit including contacts 143, 144 of relay C2 and contacts 126, 127 of the unenergized locking- relay C1. A holding-circuit for the coil 148 of the relay C3 is then established by the closure of the armature 119 with its stop 151, this holding-circuit including contacts 116, 117 of the relay C1 and contacts 141, 142 of relay C2. Subsequent impulses from the line circuit C will ring the bells A6 - - E6, in the manner previously described, and at the conclusion of the signal the parts are restored to normal position. Response to faults in line circuits. Should the circuit A be broken, the operation will proceed as for a signal interruption, the drum F makes one revolution, and the bells A6 - - E6, 200, 204 sound. The contacts 195, 196 however after a certain delay are opened by the spring 194, and the circuits B, C restored to normal condition. A similar action takes place if accidental connection establishes between the conductors 265, 267 of the circuit C. An interruption in the circuit C operates the fault bell 204, but does not affect the repeater. The system shown in Figs. 1, 7 and 8 is particularly suited for the use of closed-type break-wheels as transmitters in the A and B lines, that is break-wheels giving uniform gaps between varying circuit closures. For the lines C the break wheels should preferably be of the open type. in which the circuit closures are uniform and the gaps varying. The complete formulation of a signal should occupy a substantially uniform period for all the transmitters. Figs. 0 and 10 show panels modified for preventing fragmentary transmission of overlapping concurrent signals. These differ from the panels of Figs. 1, 7, and 8 with regard to the rotary drum f<1> and the retarded contact device f<11>, and also in the provision of additional contacts on the line-circuit relays A2<1>, C2<1>. Flexible contacts 274, 276 attached to the armatures 131 cooperate with fixed contacts 275, 277, and are connected to additional bus-bans 278. The retarded-contact device f<11> comprises an arm 193 controlled by a spring 194, and a magnet 285. When a signal from line circuit A releases armature 131, the magnet 164 for releasing the drum 168 is energized, and also the magnet 285 by closure of contact 274, 275. The subsequent closure of contacts 287, 288 energizes a magnet 297. The action proceeds as in Fig. 1, until the plate 281 of the drum 168 opens the brushes 282, 283, and opens the circuit of the magnet 297. If the armature 131 of relay A21 or B2<1> is still in retracted or abnormal position after the brushes 282, 283 are again bridged by the plate 281, the magnet 297 is energized and its armature 298 establishes a holding circuit for magnet 297 whilst releasing magnet 285. Thereupon the lever 193 is