| 摘要 |
1,164,978. Selective signalling. ROBERTSHAW CONTROLS CO. 9 Aug., 1968 [10 Aug., 1967], No. 38122/68. Heading G4H. In an alarm system a plurality of alarm contacts A1, A2 . . . B1, B2 . . . C1, C2 . . . are located at each of a plurality of alarm zones A, B, C ., each alarm zone is connected to a central station by an associated lead 7A, 7B, 7C . . . and corresponding contacts A1, B1 C1 . . . A2, B2, C2 . . . A3, B3, C3 . . . from the alarm zones are connected to the central station by associated leads P1, P2, P3 . . . In operation activation of an alarm contact causes at the central station flashing of a lamp LA, LB, LC . . . from a multivibrator MV, indicating the zone in which the alarm event lies, and also energization of an audible alarm 53 and additional visual indications 65. An operator may then acknowledge the alarm by closing contacts 36, turning off the audible alarm and steadying the zone indicator lamp by firing an associated SCR, and finally he may close an appropriate one of a plurality of zone switches SA, SB, SC . . . (determined by the visual indication of the zone in which the alarm lies) whereupon one of a plurality of lamps PL1 . . . indicating the particular alarm within the zone, will be energized. |
