How to Realize the Protection Function of PTC Self Recovery Fuses.mini blade fuse vs standard

　　How does PTC self recovery fuse achieve protection function? The actual process of PTC overcurrent circuit protection is not yet clear, and its superiority needs further exploration. So far, it is believed that PTC is a polymer based self recovery fuse that can limit current.

　　The principle of PTC self recovery fuse is to limit potentially harmful overload currents within a safe range. Specifically, excessive current flowing through the device can lead to an increase in internal heat (I2R), resulting in a temperature rise in PTC and an increase in its resistance. Before overheating occurs, PTC resistance usually only accounts for a small portion of the total impedance of the circuit. The increase in resistance of polymer PTC self-healing fuses has a non-linear characteristic, and such relatively large resistance will reduce or limit the current in the circuit to a safe range. The transition point from low resistance to high resistance is called the "jump point".

　　The heat generated by the limited current with higher resistance will maintain the temperature of the PTC self recovery fuse at a high level, resulting in high resistance. The thermal balance condition will always be maintained until the circuit loses power, the PTC gradually cools down, and the resistance value decreases. The basic principle of PTC self recovery fuse with self recovery function is that an increase in temperature will lead to an increase in resistance, and vice versa. PTC self recovery fuses achieve self recovery or return to a low resistance state by removing power from the circuit, thereby reducing the temperature of the device. Afterwards, the component can respond to future overloads at any time. If the root cause of the overcurrent problem is eliminated, the resistance will remain low; But when overcurrent occurs again, the device will switch back to a high resistance state.

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