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　　Technical standard for PPTC self recovery fuse

　　1. Rated zero power resistor

　　PPTC thermistors should be packaged as zero power resistors, and the resistance range should be indicated on the outer packaging. After withstand voltage and withstand current tests, the range of resistance change rate of each group of samples before themselves is δ | Ri before Ri/Ri before - (Rj before Rj)/Rj before | ≤ 100%

　　2. PTC effect

　　Saying that a material has a PTC (positive temperature coefficient) effect means that the material's resistance increases with increasing temperature. For example, most metal materials have PTC effect. In these materials, the PTC effect is manifested as a linear increase in resistance with increasing temperature, which is commonly referred to as the linear PTC effect.

　　3. Nonlinear PTC effect

　　Materials undergoing phase transition will exhibit a phenomenon of rapid increase in resistance within a narrow temperature range of several to ten orders of magnitude, known as the nonlinear PTC effect. Many types of conductive polymers exhibit this effect, such as polymer PTC thermistors. These conductive polymers are very useful for manufacturing overcurrent protection devices.

　　4. Minimum resistance (Rmin)/maximum resistance (Rmax)

　　At a specified ambient temperature, such as 25 ° C, the resistance value of a specific type of polymer thermistor in the circuit will be within the specified range, i.e. between Rmin and Rmax, before installing self recovery. This value is listed in the standard resistance column.

　　5. Maintain current

　　The holding current is the maximum current that can pass through a polymer PTC resettable fuse when it remains inactive. Under limited environmental conditions, the device can remain indefinitely without changing from a low resistance state to a high resistance state.

　　6. Action current

　　It is the minimum steady-state current that enables the resettable fuse series polymer thermistor to operate within a limited time under limited environmental conditions.

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