Xiamen SET Electronics Co., Ltd.
Inrush Current Limiting NTC Thermistor is a temperature sensitive resistor made of special semiconductor ceramic material with Negative Temperature Coefficient characteristics. They have a higher resistance value at room temperature. When they are energized, the temperature of the resistor body increases due to self-heating, and the resistance value decreases. Using this feature, they are used as Inrush current limiting/protection components for electrical and electronic equipment. These devices can easily and effectively limit abnormal currents, including surge currents when energized. Inrush Current Limiting NTC Thermistors used as current protection devices are also called power thermistors.
R25
Nominal Zero-power Resistance at 25 °C
Nominal value of zero-power resistance at the standard reference temperature of 25 °C, unless otherwise specified.
— (IEC 60539)
Imax25
Maximum Current at Ambient Temperature of 25 °C
Maximum value of current (d.c. or r.m.s. values for Sine wave shaped a.c.) which can be continuously applied to the thermistor at an ambient temperature of 25 °C.
— (IEC 60539)
B
B value
Index of thermal sensitivity expressed by the formula
Ra is the zero-power resistance (Ω) at temperature Ta (k)
Rb is the zero-power resistance (Ω) at temperature Tb (k)
Ta =298.15 K, Tb=358.15 K
— (IEC 60539)
δ
Dissipation Factor
Power dissipation required for a thermistor to raise its temperature by 1 K and which is generally the ratio of the power dissipation change to the resulting thermistor body temperature change at a specified ambient temperature.
— (IEC 60539)
τa
Thermal Time Constant by Ambient Temperature Change
Time required for a thermistor to respond to 63.2 % of an external step change in ambient temperature in a defined medium.
— (IEC 60539)
Rmin@Imax25
Residual Resistance
Inrush Current-limiting Thermistors value of the d.c. resistance of a thermistor when its thermal stability is reached with the maximum current passing.
— (IEC 60539)
Cmax
Maximum Permissible Capacitance
Maximum permissible capacitance value of a capacitor which can be connected to a thermistor under loading.
— (IEC 60539)
Pmax
Maximum Power Dissipation
Maximum value of the power dissipation which can be continuously applied to the thermistor at 25 °C .
— (IEC 60539)
● Switch-mode Power Supplies
● Transformers
● Inverters
● Soft-start Motors
● LED Driver Circuit
● Halogen Lamp
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Usage
1. Thermistor must be operated within the specified ambient temperature.
2. Do not clean the thermistor with strong polar solvent such as ketone, esters, benzene, halogenated hydrocarbon, to avoid damaging the
encapsulating layer.
1. Please do not apply severe vibration, shock or pressure to thermistor, to avoid surface resin or element cracking.
2. Please fix lead wires when bending or cutting. the distance between the bending point and the sealing of thermistor shall be greater than 2 mm.
Replacement
1. If thermistor is visually damaged, please replace it.
2. Thermistor is a non-repairable product. for safety sake, please use equivalent thermistor for replacement
Storage
1. Storage thermistor only in original packaging. do not open the package before storage.
2. Storage temperature range: -25 to 45 °C.
3. Relative humidity : ≤75% RH.
4. Keep away from corrosive gas and direct sunlight.
5. Period of storage: ≤1 Year.
Installation
Do not take violent action such as knocking when assembling to avoid mechanical damage.
Inrush Current Limiting NTC Thermistor (NTC) Catalog
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Over Temperature Protection（85）
Over Voltage Protection（232）
Over Current Protection（58）
Active Protection（18）
Accessories（3）
