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Why use fuse when using current sensing

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xmen_xwk

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I have seen in many appliances and circuits, that there is already a fuse and current sensing circuit for same connection/trace ? I mean whats the point of having 2 things. I believe it is used for protecting from short circuit. But why have both ? Is there any advantage of that ?

Also which one is better for as protection from short circuit, fuse or current sensing ? The problem with fuse is that, it has to be changed.
 

Hi,

Current sensing means "measuring the current". It does not necessarily mean that it detects an overcurrent situation, and it does not mean that something switches OFF.

Klaus
 

KlausST said:
Hi,

Current sensing means "measuring the current". It does not necessarily mean that it detects an overcurrent situation, and it does not mean that something switches OFF.

Klaus
Click to expand...

ah that was my mistake in explaining the question, but the circuit is measuring the current and switches off the output if it exceeds the certain limit. Same thing what a fuse does.

And question is why use both ? also which is better ?
 

A fuse is ALWAYS the protection scheme of last resort.
If the electronic current limit fails for any reason, then you still have something which will prevent a fire.

As a matter of fact............Depending on where you live and the particular circuit in question, many safety agencies require the use of a fuse regardless of whether you have other current protection methods.
 
Sometimes current limit circuits fail to work, and "something" is going to burn up.

Much better that it is an easily replaceable fuse rather than something more serious.
 

Okay I understand now but why not just use fuse?
 

Because a blown fuse is a customer service headache whereas an event which causes an over-current may be temporary and recoverable.
 

What happens if the current sensing circuit fails, either induction or via a shunt? The fuse is the last line in protection.. try a polly fuse if you don't want it tripping, but even pollys come with issues
 

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