Rui Longyuan Electronics
Rui Longyuan Electronics
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Selection rules for resettable fuses

time:2019-11-27 visit:222



1. Determine the following parameters of the circuit:

a Maximum operating ambient temperature b Standard operating current c Maximum operating voltage (Umax) d Maximum fault current (Imax)

2.Select a self-resetting fuse element that can adapt to the maximum ambient temperature of the circuit and the standard working current

Use the temperature reduction {ambient temperature (° C) operating current (A)} table and select the temperature that best matches the maximum ambient temperature of the circuit. Browse this column to see the value of the circuit's standard operating current.

3. Compare the maximum electrical rating of the selected component with the maximum operating voltage and fault current of the circuit

Use the electrical characteristics table to verify that the component you selected in step 2 will use the circuit's maximum operating voltage and fault current. Check the device's maximum operating voltage and maximum fault current. Ensure that Umax and Imax are greater than or equal to the maximum operating voltage and maximum fault current of the circuit.

4. Determine the action time

The operating time is the amount of time it takes to switch this element to a high resistance state when a fault current appears on the entire device. To provide the desired protection, it is important to know the operating time of the resettable fuse element. If you select a component that moves too fast, abnormal or harmful action may occur. If the component moves too slowly, the protected component may be damaged before the component switches to a high resistance state.

Use a typical operating time curve at 25 ° C to determine if the operating time of a resettable fuse element is too fast or too slow for the circuit. If yes, go back to step 2 and reselect spare parts.

5.Verify ambient operating temperature

Reduction rate table of ambient temperature and current value for resettable fuse

Ensure that the minimum and maximum ambient temperature of the application is within the operating temperature range of the resettable fuse element. Most resettable fuse components have an operating temperature range of -40 ° C to 85 ° C.

6.Verify the dimensions of the resettable fuse element

Use the form factor chart to compare the form factor of your selected resettable fuse with the space conditions of your application.