The Godrej Fi-Warn D-H55 heat detector has a low air flow resistance case made of
self-extinguishing white polycarbonate. The device monitors heat by using a single
thermistor which provides a voltage output proportional to the external air temperature.
The detector is designed to be connected to a two wire loop circuit carrying both
data and a 17V to 28V dc supply. The detector is connected to the incoming and outgoing
supply via terminals L1 and L2 in the mounting base. A remote LED indicator requiring
not more than 4mA at 5V may be connected between +R and -R terminals. An earth connection
terminal is also provided.When the device is energized, the inbuilt micro-controller
regulates the flow of power, and controls the data processing. The thermistor provides
an output over a normal operating range that is proportional to the external air
temperature. This voltage output is processed in the A/D converter and is transmitted
to control equipment when the device is polled.