How do fas fire alarm systems operate ?

The fas fire alarm systems operates in one of three (or more) states: normal, alarm, and trouble. The state is reported at all times on the alphanumeric display.

If the fas fire alarm systems goes into alarm, the indicating appliances throughout the building go off. These could be very loud horns for some occupancies, or softer chimes in others, such as a nursing home.

The fas fire alarm systems monitors the initiating device circuits at all times for shorts and open wiring by means of the applied DC voltage. The initiating devices are normally open. In the event of a fire they become conductive at close to zero ohms.

So, how is it possible for the fas fire alarm systems to differentiate between a non-alarm state and an open wiring fault? This is accomplished by means of an end-of-line resistor.The fas fire alarm systems also monitors the functionality of its own wiring and zone cards, and trouble is reported in the display.