Fire alarm system - with parallel detectors of different sensitivity connected via DC lines to central control

摘要

The fire alarm system has a number of detectors, of differing sensitivity, connected in parallel via DC lines to a central control. The detector with the lightest sensitivity and that with the least sensitivity are connected via respective rectifiers with opposing directions of conduction, to the DC lines. The central control is provided with a switching device for responding to the voltage polarity of the DC lines corresponding to the detector with the highest sensitivity, and a further switch unit, operated via the detector with the least sensitivity, with an acoustic or visual alarm operated via the two switch means. The second switch unit may be used to operate a sprinkler system etc.