A conventional fire alarm serves the same purpose as any other normal fire alarm that you are more likely to find in large corporate buildings. Although their usage in large buildings is significantly lesser than their usage in smaller residential complexes, the conventional fire alarm system has not quite died out completely.
Conventional Fire Alarm
This system uses a set of circuits connected to both the sensors and the initiating device. A parallel connection is employed to assure that any detection of a fire in any part of the building is instantly noticed. When the smoke or temperature reading rises beyond a particular value, the sensor detects the anomaly and sends a signal to the hooter and the control panel through the internal circuitry.
Let us now find out more about the initiating device circuit in a conventional fire alarm system. When the resistance of the circuit is lowered due to the detection of a fire, the Signalling Line Circuit kicks in. In a conventional circuit, the density of the information is vastly lesser than a modern system. This is because there is a limit to the number of operating circuits that can be used in a single building.
The IDC (Initiating Device Circuit) is part of a massive interconnection of devices in the same area of fire-security. It sends three bits of data about this area to the main control panel: trouble, alarm, and normal. The alarm might use an LED or LCD display as a flashing indicator in case the signal sent is ‘trouble’ or ‘alarm’.
Multiple zones, each with its own set of circuits, can be connected to a single control panel in a conventional system. The tabular nature of major commercial establishments consisting of numerous floors allows these zones to be arranged in a matrix format. The linear intersection of a particular floor and a device will provide the corresponding information for that node. The information density, however, is always directly dependent on the sheer number of circuits. Conventional fire alarms also use graphical representations to represent boundaries for different zones in a building.