Patent GB-191513619-A (GB)
Title: Improvements in Fire Alarm Signaling Means.
Inventor: MCFELL JUDSON
IPC: G08B27/00
Filed: 1915-09-24
Abstract: 13,619. McFell, J. Sept. 24. .Fire - alarm systems, specially adapted for use in factories &c., are arranged with several separate loops A, B, C all fed from the same battery 10 and leads 11, 12, and each loop having its own central station, at which is placed a normally-energized high - resistance test magnet 27. The normally-closed test circuit also passes through alarm bells and twice through each manual transmitter 22, the arrangement being such that the remaining transmitters of a section are rendered inoperative when one transmitter is sending its code signal. Each loop A, B, C comprises a circuit from the main 11 through magnet 15, main switch 17, and magnet 18, to the transmitters 22, lead 24, test magnet 27, through the transmitters 22 again, leads 33, 34, bells 38, and back to the main 12, through wire 41, switch 17, and recorder 13<a>. The magnets 15, 18 are not sufficiently energized to attract their armatures owing to the high resistance of the test magnet 27. Upon the occurrence of a fault, say at the point x or y, the test-magnet armature 43 drops and closes the circuit of a bell 60 at the central station. Emergency test and signalling circuits may then be established by the attendant closing one or other of the switches 56<x>, 57 which connect the wires 19, 41 respectively to opposite sides of the test magnet. The position of the fault may be ascertained .by testing which of the switches 56<x>, 57 re-energizes the test magnet 27. At each transmitter 22, one pair of wires is connected to switch arms 55, 56, which are themselves normally coupled through a switch 51. The other pair of wires is connected to a bifurcated arm 54 resting on the code-wheel 52 and adapted, on rotation of the wheel, to make contact with each arm 55, 56. When an alarm transmitter is operated, the switch 51 is first opened, and the armature of the test magnet drops and, in doing so, cuts itself out at the switch 29. As the code-wheel 52 rotates, impulses are sent through a low-resistance circuit passing from the main 11 through magnets 15, 18 to the double switch arms 54 of the transmitters on the right-hand si'de of that operating, the double switch arm 54 and switch arm 55 of the operating transmitter, gongs 38, and register 13<a>, to the main 12. If two or more transmitters 22 of section A are operated simultaneously, only the left-hand transmitter sends its signal, the other transmitters being cut out at the switch 51 of the operating transmitter. The magnet 15, by intermittently closing the contacts 70, causes the gongs of sections B, C to be rung, their circuits being closed through the switches 51 of the transmitters 22b, 22<c>. This arrangement ensures that, if a transmitter in section B is operated at the same time as one in section A, each set of gongs will give the signal corresponding to the local transmitter. The magnet 18 attracts its armature at the first current impulse, short-circuits itself through a switch 65, and also raises a latch 64 from engagement with a clock-work train. An arm 62 carried by a spindle of the clock-work rotates slowly and, after an interval long enough to allow the code signal to be transmitted, engages and resets the armature 43 of the test magnet 27. The latch 64 may also be operated by a lost-motion link from the switch arm 29. The circuit of the test bell 60 is opened after a short ring, by an extension of the latch 64. The alarms in each section are registered by instruments 13<a>, 13<b>, 13<c> local to each section, and also by a master register 13 situated in one of the main leads 11, 12. To enable drill signals to be given, a transmitter 80 having interchangeable code-wheels is provided. The wheel controls two pairs of contactarms, one pair being adapted to close the circuit of the gongs 38, and the other pair to close the circuit of the magnet 15 and thereby operate the gongs 38b, 38<c>.