22 Mar
2016
22 Mar
'16
8:20 a.m.
From: drlegendre: Monday, March 21, 2016 6:50 PM
I don't quite get what makes this DigiKey part
suitable for the role of a
fused resistor. I do see that it has specs for 'fusing behavior' but that
aside, I don't see that this series is marketed / sold as a "fusible
resistor".
I take "UL1412 recognised fusing" (sic) on the first line of the data sheet
to mean that they do market them that way.
One reason I question it, is the fact that the fusing
ratings are only
plotted for like 40X or 50X expected current. Can the circuit under
protection be relied upon to produce those levels of current, even under
hard-fault conditions?
I read a little over 1000 seconds to fuse at 10W, which is only a
few times the 2W rating. Admittedly, 20 minutes at 5X load
amounts to a pretty slow fuse. I can only assume their concern
is fire prevention, rather than circuitry protection.
With regard to the suggestion of a fuse and a resistor, you'd
need more room (likely not a problem), and a flameproof
version of the resistor. I don't know anything about UL
ratings, so I don't know if that could be made OK there or
not.
Vince