The detector indicates fire hazards using the built-in LED indicator and alarm outputs ALARM and TAMPER. These outputs must be connected to control panels complying with EN 50131-3. The SD-282 ST consists of two independent detectors – an optical smoke detector and a heat detector. The optical smoke detector works on the principle of scattered light and is very sensitive to dust particles which are present in smoke. There is also a built-in heat detector for detecting fire which generates heat quickly with a small amount of smoke. The microprocessor performs digital analysis for a high false-alarm immunity.