Description

Conventional panels have been around ever since electronics became small enough to make them viable. Conventional panels are used less frequently in large buildings than in the past, but are not uncommon on smaller projects such as small schools, stores, restaurants, and apartments.

A conventional fire alarm control panel employs one or more circuits, connected to initiating devices (usually smoke detectors, heat detectors, duct detectors, manual pull stations, and sometimes flame detectors) wired in parallel. These sensors are devised to dramatically decrease the circuit resistance when the environmental influence on any sensor exceeds a predetermined threshold. In a conventional fire alarm system, the information density is limited to the number of such circuits used.

To facilitate location and control of fire within a building, the structure is subdivided into definite areas or zones. Floors of a multistory building are one type of zone boundary.

An Initiating Device Circuit (known as a Signaling Line Circuit (SLC) in addressable systems) connected to multiple devices within the same “zone” of protection, effectively provides 3 bits of information about the zone to the panel; normal, trouble, and alarm. The state of each initiating device circuit within a zone displays at the fire alarm control panel using visible indications, such as a flashing LED/light or an LCD display.

The panel may employ a graphical representation of the zone boundaries on a floor plan (zone map) using textual descriptions, illuminated icons, illuminated sections, or illuminated points on the map corresponding to initiating circuits connected to the fire alarm control panel. Annunciators that do this are called graphic annunciators.