Siemens Aktiengesellschaft

Otto W Moser

Peer Thilo

Romuald Von Tomkewitsch

A method and apparatus for inspecting a danger alarm system, such as a fire alarm system, having a plurality of discrete alarm units which are connected to a central station having a means for cyclically sampling and connecting the alarm units to a like plurality of evaluators permits the alarm units to be connected individually or in groups to an inspection display without suppressing the display of an actual alarm signal which may be received during the inspection. A first report of an alarm unit to be inspected is evaluated as an inspection report and an actual alarm report from the same alarm unit arriving after the inspection report is evaluated and displayed as an alarm report. Given alarm units which emit multi-level or analog signals, the alarm unit signals are evaluated in the central station with two threshold circuits, the evaluator at the central station being switched during an inspection to a less sensitive state and the inspection signals being evaluated by a lower threshold stage and a true alarm signal which may occur during an inspection being evaluated as such by an upper threshold stage.

Method and apparatus for inspecting a danger alarm system

In a danger alarm system, such as a fire alarm system, the availability of the system is increased by decentralization of the system intelligence. For this purpose, the entire system is subdivided into small system modules which are fully functional in and of themselves. Each system module has connection installations for one or more alarm circuits or one or more subordinate system modules, a programmed control for interrogation and evaluation of alarm signals, as well as connections for display operation and registration elements. One of the system modules serves as the central station, as the remaining system modules are subordinate to the central station in one or more hierarchical levels.

Danger alarm system

A danger alarm system, for example, fire alarm system, utilizing a plurality of detectors which are connected to a central exchange over respective call circuits, the central exchange is provided with a memory in which characteristic data for each connectable detector can be stored. Data is cyclically sampled from the respective individual detectors and simultaneously therewith rated values for the corresponding detector are formed from the stored data and compared with the sampled data and, if necessary, alarm or trouble signals are derived from the comparison results.

A fire alarm system comprises a plurality of alarms which may be operated via an alarm loop and which, being subject to selective interrogation, each alarm transmits an analog value of a particular characteristic of a fire to a central control, the analog value being tapped from a detector for that characteristic. Each alarm comprises an alarm circuit which has a load resistor which can be connected in parallel to the alarm loop by means of a timing element and which amplifies the current which characterizes the alarm at the instant of interrogation.

Fire alarm system comprising a plurality of alarms which may be operated

A fire alarm system has a central control connected to an alarm loop composed of a plurality of fire alarm circuits. Prior to an interrogation of the alarm circuits, the same are disconnected from a supply voltage and supplied by respective capacitors which are charged during connection of a full supply voltage. The individual alarms are subsequently reconnected in the alarm loop in a given sequence by a new voltage change, at a reduced voltage, and each alarm circuit is operable to connect the following alarm circuit to the loop and thus to the line voltage at a time delay corresponding to a measured value of a fire characteristic being monitored by that alarm circuit. In a central analysis device, the relevant alarm circuit address can be derived from the number of preceding increases in line current, and the associated measured value can be derived from the length of the switching delay of the corresponding alarm circuit. Different sequences of applying line voltage may be used such that three line voltage states of 'rest interval--interrogation--capacitor charge' and 'rest interval--capacitor charge--interrogation' and also the different durations of these states in that the line voltage state 'rest interval' is approximately one hundred times greater than is common to the other line states.

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Munich, Germany

Otto W Moser