resettable PTC fuse to replace a normal fuse

Thread Starter

Seaadhotm

Joined Jan 20, 2019
1
I am designing an SMPS power supply board and i want it to be long-life.

Most of the boards use a fuse in and a MOV varistor to protect against over-voltage and over-current and also inrush current . I am looking for a resettable fuse to prevent the overhead of replacing the fuse in case of blowing up.

Can i use a PTC resistor like this one in the AC side of the power supply ? instead of the normal fuse. the right side connects to a flyback converter.
i also want to add an NTC resistor for inrush current protection.
snapshot.JPG
I have also came across a resettable wire-wound resistor , what is the difference ?
 

ian field

Joined Oct 27, 2012
6,539
I am designing an SMPS power supply board and i want it to be long-life.

Most of the boards use a fuse in and a MOV varistor to protect against over-voltage and over-current and also inrush current . I am looking for a resettable fuse to prevent the overhead of replacing the fuse in case of blowing up.

Can i use a PTC resistor like this one in the AC side of the power supply ? instead of the normal fuse. the right side connects to a flyback converter.
i also want to add an NTC resistor for inrush current protection.
View attachment 168256
I have also came across a resettable wire-wound resistor , what is the difference ?

Every once in a while I see an SMPSU that sacrificed itself to save the fuse - a Polyfuse also needs fault current stuffed into it for a finite time period.

The sort of failure you're trying to avoid usually makes a mess whether the fuse blows or not - either way; someone's going to have to open the case.
 
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