Fuse question

[K]

I have MQ3 fuse. The datasheet says that it has maximum
power dissipation of 0.48 Watts, ampere rating of 3 amps and
maximum voltage drop of 0.2 volts. My question is that if it
dissipates 0.48 watts when the current is almost 3 amps, then how
much power does it dissipate when the current is for example only
0.1 amps? How can I find equal resistance for the fuse?

Here is a link to the datasheet:
http://www.belfuse.com/Data/DBObject/MQ.pdf


Thanks

 

[Dave Platt]

I have MQ3 fuse. The datasheet says that it has maximum
power dissipation of 0.48 Watts, ampere rating of 3 amps and
maximum voltage drop of 0.2 volts. My question is that if it
dissipates 0.48 watts when the current is almost 3 amps, then how
much power does it dissipate when the current is for example only
0.1 amps? How can I find equal resistance for the fuse?

You'll probably have to actually measure it, under different levels of
current loading, to determine its actual characteristics. Fuses are
not simple fixed-value resistors... they're almost always nonlinear,
especially at the high-current end of their range.

To a first approximation, the dissipation is going to decrease as the
square of the current decrease. I suspect that the actual power
dissipation at 0.1 amps is going to be less than that, as the fuse's
temperature will have decreased somewhat and its resistance will thus
have fallen a bit.

--
Dave Platt <dplatt@radagast.org> AE6EO
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