Electrical equipment such as motors, transformers, switching power supplies, electric heaters, and incandescent lamps will generate a surge current that is many times higher than the normal operating current at the moment of starting. Use the relatively large zero-power resistance of the power NTC thermistor to suppress the surge current at the moment of starting, so that the surge current at the moment of starting is not excessive. Therefore, the components in the electrical appliance are protected, and the working life of the electrical equipment can be greatly extended.

After the power NTC thermistor completes the function of suppressing the surge current. Due to the continuous action of its current, as the temperature of the thermistor body increases, its resistance value will drop to a very small extent, and the power consumption can be neglected and will not affect the normal operating current. This not only suppresses the surge current but also ensures that the working efficiency of the electrical equipment is not affected. The above workflow can be briefly summarized as:

The following is a comparison chart of surge current between used and unused power NTC thermistors.

It is a low-cost, simple and reliable method to use power NTC thermistor to suppress the surge current when the electrical appliance is turned on. Because of its good use effect, it has been widely used.


The power NTC thermistor has the characteristic that the resistance value changes significantly with the temperature change, and the resistance value decreases as the temperature rises. It is made of transition metal oxides such as manganese (Mn), cobalt (Co), nickel (Ni), iron (Fe), copper (Cu), and aluminum (Al) as the main materials and using ceramic technology. Its composition structure is: NTC heat-sensitive chip, welding layer, protective layer, lead and other components.

Power type NTC thermistor structure diagram.

The power NTC chip produced by YAXUN Electronics adopts special materials and technology, the chip ceramic matrix is dense, and the grain growth is uniform;
The welding contact area between the ceramic substrate and the lead is large;
Silicone resin encapsulation, good heat resistance and heat dissipation performance. It can withstand large steady-state currents, has a strong ability to withstand surge currents, and has high product reliability.
        Main parameters of power NTC thermistor.

1. Rated zero power resistance (R25):
It is also called the nominal resistance value. Unless otherwise specified, it refers to the resistance value of a power NTC thermistor measured at an ambient temperature of 25°C. Commonly used resistance values are 2.5Ω, 5Ω, 10Ω, etc., and the commonly used resistance value errors are: ±15%, ±20%, ±30%, etc.

2. Maximum steady-state current (A):
The maximum current that can be continuously applied to the power NTC thermistor at the nominal ambient temperature.

3. Maximum allowable capacitance (Joule energy) (UF): Under load, the maximum allowable capacitance of a capacitor connected to a power NTC thermistor.
4. Operating temperature range (℃):
The ambient temperature range in which the power NTC thermistor can work continuously in the zero power state. It is determined by the upper limit category temperature and the lower limit category temperature.


         The main parameter range of YAXUN Electronics' power NTC thermistor is:
         R25 resistance range: 0.2Ω——400Ω;
         Working temperature range: -40℃——200℃;
         The largest steady-state current range: 0.1A-90A;
         The largest impact capacitance range: (AC240V) 47UF-12000UF.
         Diameter range of the chip: D3mm——D50mm;

R25-Widerstandsbereich: 0,2Ω——400Ω;
          Arbeitstemperaturbereich: -40℃——200℃;
          Der größte Dauerstrombereich: 0,1A-90A;
          Der größte Stoßkapazitätsbereich: (AC240V) 47UF-12000UF.
          Durchmesserbereich des Chips: D3mm——D50mm;