①Nominal resistance Rc: generally refers to the actual resistance value of the thermistor when the ambient temperature is 25 degree . ②Actual resistance value RT: the resistance value measured under certain temperature conditions.
③Material constant: It is a parameter describing the physical properties of the thermistor material, and it is also an index of thermal sensitivity. The larger the B value, the higher the sensitivity of the thermistor. It should be noted that in actual operation, the B value is not a constant, but increases slightly with the increase of temperature.
④Temperature coefficient of resistance T: It represents the change rate of resistance value when the temperature changes by 1 degree , and the unit is percent / degree .
⑤Time constant τ: The thermistor has thermal inertia, and the time constant is a parameter describing the thermal inertia of the thermistor. It is defined as the time required for the temperature of the thermistor body to change by 63.2 percent of the difference between the two specific temperatures when the ambient temperature suddenly changes from one specific temperature to another specific temperature in a state of no power consumption . A smaller τ indicates a smaller thermal inertia of the thermistor.
⑥ Rated power PM: Under the specified technical conditions, the dissipated power allowed by the thermistor for long-term continuous load. The rated power shall not be exceeded in actual use. If the ambient temperature in which the thermistor operates exceeds 25 degree , its load must be reduced accordingly.
⑦ Rated working current IM: the nominal current value specified by the thermistor in working state.
⑧Measurement power Pc: under the specified ambient temperature, the electric power consumed when the resistance value change caused by the heating of the thermistor body by the test current does not exceed 0.1 percent .
Thermistor
Thermistor
⑨ Maximum voltage: For NTC thermistors, it refers to the maximum DC voltage that is allowed to be continuously applied under the specified ambient temperature without causing the thermistor to cause thermal runaway; for PTC thermistors, it refers to the specified voltage. At ambient temperature and in still air, the maximum DC voltage that is allowed to be continuously applied to the thermistor and ensures that the thermistor works normally in the PTC characteristic part. ⑩Maximum working temperature Tmax: Under the specified technical conditions, the maximum temperature allowed by the thermistor for long-term continuous operation.
⑾Switching temperature tb: The temperature at which the resistance value of the PTC thermistor begins to jump.
⑿ Dissipation coefficient H: The power dissipated by the thermistor when the temperature increases by 1 degree , the unit is mW/ degree .
