The PS-24H photoelectric smoke detector utilizes two bicolored LEDs for indication of status. In a normal standby condition, the LEDs flash green every 3 seconds. When the detector senses that its sensitivity has drifted outside its ULlisted sensitivity window, the LEDs will flash Red every 3 seconds. When the detector senses smoke and goes into alarm, the status LED will latch on Red.
The detector utilizes an infrared LED light source and silicon photo diode receiving element in the smoke chamber. During a normal stand by condition, the receiving element receives no light from the pulsing LED light source. In the event of a fire, smoke enters the detector smoke chamber and light is reflected from the smoke particles to the receiving element. The light received is converted into an electronic signal.