Today, all fire alarm systems can be broadly classified into three main categories: threshold (conventional), addressable, and addressable-analogue fire alarm systems. Each of these system types has its own set of advantages and limitations.
Threshold Fire Alarm Systems
A threshold fire alarm system is based on non-addressable detectors of various types. Each detector has a predefined activation threshold – when this threshold is reached, the detector sends an alarm signal to the control panel. The system is designed using zone circuits, with a chain of non-addressable detectors connected to each zone. When any detector in a zone is triggered, the system reports an incident within that specific zone, although the exact detector location remains unknown.
The main advantage of a threshold system is its low equipment cost. Key disadvantages include delayed detection, lack of detector condition monitoring, and poor event localization.
Addressable Fire Alarm Systems
An addressable fire alarm system offers a more advanced level of fire protection. In such systems, detectors of various types have individual identifiers and are periodically polled by the control panel. In response to polling, detectors can transmit information about their current status as well as the presence or absence of abnormal conditions within their monitored area.
The advantages of an addressable system include an optimal balance between cost and performance, along with continuous monitoring of detector health. Its primary drawback is slower reaction time compared to more advanced systems.
Addressable-Analogue Fire Alarm Systems
Addressable-analogue fire alarm systems represent the most advanced class of fire protection solutions. It is important to clarify that the term “analogue” does not refer to the method of data transmission or processing, but rather to the fact that detectors are polled continuously.
The fundamental difference is that all data interpretation occurs at the control panel, not within the detectors themselves. Detectors transmit detailed readings – temperature levels, presence of smoke, gas concentrations, and other sensor data – while the control panel’s processing unit analyses this information and determines whether an alarm condition exists.
The key advantages of addressable-analogue systems include high information accuracy, rapid response, and continuous equipment status monitoring. Their only significant drawback is the higher equipment cost inherent to this technology.