Successor to electromechanical vane types, the 2SE is designed to sense and protect against the loss of airflow in power supplies, data processing units, or any other commercial or military electronic equipment where it is necessary to recognize the loss or reduction of airflow. PTC sensors remain at a low, relatively constant level of resistance over a wide temperature range then abruptly increase resistance logarithmically at an elevated temperature known as an anomaly temperature. As the transition is approached, a slight temperature rise causes a dramatic increase in resistance. Power supplied to the PTC sensor will cause it to self-heat to a high resistance condition. Sufficient airflow will cool the sensor to its low resistance level.
Insufficient airflow allows the sensor to self-heat and reach a high resistance state.
100,000 cycles Operating Temp. The gray region is the deadband, in which sensor could be in either the fault or the no fault condition. Configuration Below is the typical 2SE configuration, but others are available. Drawing is for reference purposes only. Texas Instruments Incorporated.