CE Lead Free PPTC Thermistor Multipurpose For Motor Overload

Strong Reliability Smaller Size Polymer PPTC Thermistor Applied To Motor Overload

PPTC thermistors ((Polymer Positive Temperature Coefficient)) are made of polymer material filled with carbon black particles. This material has a certain ability to conduct electricity, so it can pass the rated current. If the current through the thermistor is too high, its heating power is greater than the cooling power, at this time the temperature of the thermistor will start to rise continuously, and at the same time the polymer matrix in the thermistor starts to expand, which makes the carbon black particles separate, and causes the resistance to rise, which very effectively reduces the current in the circuit. At this time, there is still a small current flowing in the circuit, and this current keeps the thermistor at a high enough temperature to maintain a high resistance state. When the fault is eliminated, the PPTC thermistor will cool down quickly and will return to the original low resistance state, so that it can work again like a new thermistor.
 

The resistance-temperature characteristics of the thermistor can be approximately expressed by the following formula: R=R0exp{B(1/T-1/T0)}: R: resistance value at temperature T(K), Ro: temperature T0, ( K) resistance value, B:B value, *T(K)=t(ºC)+273.15. In fact, the B value of the thermistor is not constant, and its variation varies depending on the material composition, and the maximum can even reach 5K/°C. Therefore, when formula 1 is applied in a larger temperature range, there will be a certain error between the measured value and the actual value. Here, if the value of B in Equation 1 is calculated as a function of temperature shown in Equation 2, the error between the measured value and the actual value can be reduced, and it can be considered to be approximately equal.

Features
 

1 Easy to set up with safety and stability.

2 Smaller size that saves board space and cost.

3 Resettable circuit protection.

4 Fast time-to-trip.

5 Low resistance.

6 Lead-free and compliant with the European Union RoHS Directive.

APPLICATION: