Reply
Thu 30 Jul, 2015 11:08 am
Fuses are installed in a circuit to prevent current flowing through them when the amperage exceeds the fuse rating. However, on one of my electronic test equipment, not only has the AC fuse blown (at the AC input) but the internal power supply (inside the equipment) is also damaged due to the voltage surge. If fuses are inserted to protect equipment, how did the current pass through a blown fuse (open circuit) and damage my power supply ? For reference , my AC Fuse rating is 3.15A/ 250V and this equipment was used in China, although manufactured here in USA.
@parakeet,
There was no current through the blown fuse. That would be impossible unless it arced over the gap in the fuse.
However, what is likely is the fuse wasn't quick enough to respond to the surge.
The speed of the power surge generated enough of a quick hit to bypass the blowing of the fuse in such a time as to NOT protect the supply. The supply took the hit before the fuse could protect it.
When I buy effective power strips with decent surge protection...I look at the specs of the power spike protection....and they indicate something in the order of nanoseconds of response time. Of course, they industry for power surge protections power strips... also show specs (measured in joules) as to how much of a power hit they take as well - valuable in lighrning prone areas.
https://en.wikipedia.org/wiki/Surge_protector
Stumble It!
Tweet This
Bookmark on Delicious
Share on Facebook
Share on MySpace