Resistor/Fuse replacement (DEC H7104-D)

[Vincent Slyngstad]

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