Types of thermistor:
According to the heating method classification-direct heating thermistor, side heating thermistor.
According to temperature change (temperature change) characteristics classification-positive temperature coefficient (PTC), negative positive temperature coefficient (NTC) thermistor.
Classified according to structure and shape-wafer-shaped (sheet-shaped), cylindrical (pillar-shaped), circle-shaped (washer-shaped) and other thermistors.
According to the sensitivity classification of temperature change-high sensitivity type (abrupt change type), low sensitivity type (gradual change type) thermistor.
The main parameters of the thermistor:
Nominal voltage: refers to the voltage value of the thermistor for voltage regulation corresponding to the nominal operating current at a specified temperature.
Working current: refers to the specified current value of the thermistor for voltage stabilization under normal working conditions.
Voltage stabilization range: refers to the range value of voltage stabilization thermistor to stabilize voltage within the specified ambient temperature range.
Maximum voltage: refers to the highest voltage value that the thermistor is allowed to apply continuously when the thermistor is working normally at the specified ambient temperature.
Insulation resistance: refers to the resistance value between the resistor body of the thermistor and the insulating case under the specified environmental conditions.
In addition to the basic indicators such as nominal resistance, rated power and allowable deviation, there are the following indicators:
Measurement power: refers to the power consumed when the resistance body is heated by the measurement power supply and the resistance change does not exceed 0.1% at the specified ambient temperature.
Material constant: an indicator of the thermal sensitivity of the thermistor. Generally, the larger the value, the higher the thermistor's sensitivity and resistivity.
Temperature coefficient of resistance: It indicates the relative change of the resistance value caused by the temperature change of the thermistor under zero power condition for every 1 ℃ change.
Thermal time constant: refers to the thermal inertia of the thermistor. That is, in the state of reactive power, when the ambient temperature changes suddenly, the time required for the temperature of the resistor to change from the initial value to 63.2% of the difference in the final temperature.
Dissipation coefficient: refers to the power dissipated for every 1 ° C increase in the temperature of the thermistor.
Switching temperature: refers to the temperature when the zero-power resistance value of the thermistor is twice the lowest resistance value.
Maximum working temperature: refers to the maximum temperature that the thermistor is allowed to withstand when working continuously for a long time under the specified standard conditions.