Many people often encounter confusion when reading the parameter information of self recovery fuses, as they do not understand the meaning of the symbols used, which causes reading difficulties. Here is an explanation from the symbol of self recovery fuse parameters, hoping to help everyone:
The maximum operating current of the IH self-healing fuse element at an ambient temperature of 25 ℃
The minimum current for it self recovery fuse element to activate protection at an ambient temperature of 25 ℃
Imax self-healing fuse element can withstand maximum current
The maximum operating voltage of the Vmax self recovery fuse element
The maximum voltage that the Vmaxi self-healing fuse element can withstand in a blocked state
The initial minimum resistance value of the Rmin self recovery fuse element before operation
The initial maximum resistance value of the Rmaxi self recovery fuse element before its final operation
The holding current Ih is the maximum current that can be passed through the polymer PTC thermistor of the self resetting fuse series when it is not in operation. Under limited environmental conditions, the device can maintain an infinite amount of time without transitioning from a low resistance state to a high resistance state.
The minimum steady-state current at which the self resetting fuse series polymer thermistor operates within a limited time under limited environmental conditions.
The maximum current Imax (withstand current value) is the maximum operating current of the self resetting fuse series polymer PTC thermistor for safe operation under a limited state, which is the withstand current value of the thermistor. Beyond this value, the thermistor may be damaged and cannot be restored.
The consumption efficiency of Pdmax polymer self recovery fuse in the circuit under normal working conditions
The maximum working resistance Vmax is the voltage that a polymer self recovery fuse can withstand. If the voltage is too high, the self recovery fuse device may fail to protect the circuit or provide false protection
The maximum withstand voltage Vmaxi is the maximum voltage that polymer self recovery fuse components can withstand. If the voltage exceeds this value, the self recovery fuse components may be damaged and fail, and cannot effectively protect the circuit
The initial resistance Rmin is tested at an ambient temperature of 25 ℃ before being installed in the circuit, and the resistance value of the polymer PTC thermistor of the self resetting fuse series is determined.
The initial maximum resistance value Rmax is the maximum resistance value measured one hour after the self resetting fuse series polymer PTC thermistor is activated or refluxed and installed in the circuit board at room temperature.
What is the relationship between IH and IT? Why is there a difference? Most of our products have a 2:1 relationship between IT and IH. Some products may be as low as 1.7:1, while others may be as high as 3:1. The different materials, processing methods, and welding forms of thermistors determine the ratio of IT to IH. The actual ratio of most of our products is 2:1.
What is the difference between Rmin, Rmax, and Rl? Under specified conditions (such as 20 ℃), the resistance value of a specific model of self recovery fuse before use is within a specified range, that is, between the minimum value (Rmin) and the maximum value (Rmax). The maximum resistance value of a polymer PTC thermistor after 1 hour of operation at room temperature or one hour after soldering to the circuit board is Rl.
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