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 degrees (class A1S) to 78 degrees (Class BS).
 
The 52051RE uses the same thermistor and microprocessor technology to provide an alarm when the rate of rise in temperature exceeds 10 degree/minute (typical) or if the temperature exceeds a threshold of 58 degrees. With the implementation of the Series 200 Advanced Protocol, any model can be software configures to be wither a fixed 58 degree, a fixed 78 degree unit or a 58 degree with rate of rise device. For backwards compatibility and approval continuity, three separate versions continue to be available as separate part numbers.
 
The sensing elements of all three heat sensors are panel controllable through the Series 200 Advanced Protocol so the sensitivity threshold of each element can be changed by the panel offering the ability to customise the device for the changing use of the area it is protecting.