● Basic principles
The full name of polymer PTC is "polymer positive temperature coefficient thermistor", which has excellent overcurrent protection function due to the special properties of its material. Polymer PTC is connected in series in the circuit (as shown in Figure 1), and under normal circumstances, it is in a low resistance state, and the working current can pass smoothly; When an abnormally high current occurs in the circuit, its impedance rapidly increases (in a high resistance state), effectively limiting the passage of high current and protecting the circuit from damage (as shown in Figure 2). After the fault current is eliminated, the resistance of the polymer PTC rapidly decreases and returns to a low resistance state.

Figure 1	Figure 2

　

● Selection Guide
The use of polymer PTC is both safe and convenient, and is a win-win strategy. When selecting, the first consideration should be that the operating voltage should be less than or equal to the maximum voltage that the polymer PTC can accommodate; Next is to match the size of the working current. The working current (IH) listed in the specification refers to the current value at a working environment temperature of 25 ℃. If the actual working environment temperature is different from it, temperature current reduction factors should also be considered, as shown in Figure 3. Finally, the installation method should also be considered, such as plug-in and optical chip insertion. Other technical indicators refer to the specification sheet. If there are any special circumstances, please contact our company directly to inquire about special processing.

● Application scope:
The SVRF240 series products are suitable for low operating currents (less than 50mA) and high rated voltages (rated current 0.005A to 2.0A, rated voltage up to 240Vac, up to 265Vac). All products comply with ROHS standards, reducing board space occupation, lower maintenance and replacement costs, and fast action time, which helps to reduce the temperature caused by current in motor windings and vulnerable electronic components, reducing interference and disconnection phenomena. Can be used in fields such as continuous operation motors, intermittent operation motors, transformers, power supplies, fans, blowers, electronic controls, etc