The 52051E and 52051HTE are fixed temperature analogue addressable sensors employing low mass thermistors and microprocessor technology for fast response and linear temperature sensing. Their linear response allows these sensors to be used to signal temperatures over the range of 58°C (Class A1S) to 78°C (Class BS). The 52051RE uses the same thermistor and microprocessor technology to provide an alarm when the rate of rise in temperature exceeds 10°C/minute (typical) or if the temperature exceeds a threshold of 58°C (Response Class A1R). With the implementation of the Series 200 Advanced Protocol, any model can be software configured to be either a fixed 58°, a fixed 78° unit or a 58° with rate of rise device. For backwards compatibility and approval continuity, three separate versions continue to be available as separate part numbers.