>>What is the typical reliable opening current and opening
>>TIME of a fuse compared to the safe holding current? Have
>>you ever looked at it?
>A typical fast blow type will open in a few seconds with 2x
>overload
>and the opening time decreases exponentially with higher
>overloads.
I suppose it depends on the definition of a few seconds.
Littlefuse says the opening time of a low current 3AB fast
acting fuse fuse is 15 seconds maximum at 200% overload, and
it will eventually fail if operated near ratings for long
accumulated periods of time.
On the other hand an electronic overload circuit will
disconnect in 15mS or less at 110% overload, and never
fatigue and open falsely.
>>What is the reliable opening point (where it goes
>>near-infinite resistance) of a 1/4 watt resistor compared
>>to
>>safe working current? Have you ever looked at that?
>I have no idea. I would not use a 1/4 watt resistor as a
>fuse.
>>Under what conditions would the resistor open?
>Properly sized, it will do the job.
How do you know that if you said you have no idea what the
opening time is?
I have tested resistors and they are very poor and very
unpredictable compared to a fuse, which by itself is nearly
useless for protecting a grid.
73 Tom
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