Heat detector MD9908

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MD9908 140°C HEAT DETECTOR MD9908 is an automatic addressable heat detector with alarm threshold of 140°C. Self diagnostics function generates fault condition in case of sensor failure or degradation. The detector address is programmed by the central unit or by software tools. The detector is supplied with its address unit for the loop/branch interface. The detector is composed of two parts: ■the sensor to be installed in the room to monitor ■the Loop Interface Box, mounted outside the room monitored by the sensor. The two objects are connected with a cable whose maximum length can be 30 m. The température alarm is generated by a thermistor installed on the sensor, with a very low time constant which allows for a very fast answer on ambient air température variations. Its position at the detector center offers a uniform détection over 360 degrees. The thermistor is protected against shocks through a dedicated cover fixed on the detector frame. The measured signal is handled by a conditioning circuit and sent to the sensor microcontroller that generates the alarm if the value is above a predefined threshold. The detector continuously monitors the thermistor component and is able to provide a fault signalization in case of sensor failure. The communication through the loop with Central Unit is performed by control cards, which provide to the detectors the 24Vdc power supply on which a serial transmission signal using MD2 protocol is modulated. Loop Interface Box with built in short circuit isolator. The detector address is programmed by software from the Central Unit. If an alarm is detected, an optical signalization (red Led) on the Loop Interface Box flashes.