electronic fuse

An electonic fuse is essentially a mixture of a match and a fuse, along with some wires. An electronic fuse is not a fuse as such, but more of an ignitor.

An electronic fuse consists of:

• Wires (2)
• Some smokeless gunpowder (or equivalent)
• a small heating coil

                     ,-----------------.
                    /                    \
wire----------------------o               |
                          §               |
wire----------------------o               |
                    \                    /
                     '-----------------'

The little § sign is the heating coil, the big thing is the gunpowder, and the wires are the wires :) I was never a renowned ASCII artist, nor will I ever be.

In any case: when there is electric current passing through the wires, the heating coil gets hot and ignites the gunpowder, which then burns long enough the ignite whatever the igniter was ment to ignite (such as pyrotechnic effects). This process happens very very quickly (a few hundreths of a seconds at the most), which takes the guesswork out of pyrotechnics.

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Back to the node on pyrotechnics
Please read the disclaimer. Also, make sure you have read the Pyrotechnics safety tips. SAFETY FIRST

 

This term also applies to a polymeric positive temperature coefficient (PPTC) device, or as it is more commonly known, a self-resetting fuse. The fuse can take any shape, as it is made from a polymer compound. This compound is impregnated with conductive particles.

In operation, a PPTC fuse conducts electricity through the conductive particles in contact with one another in the polymer matrix. When the current rises to a preset level, the heated polymer expands to the point where the conductive particles are no longer touching one another, cutting off the flow of electricity. When the fuse cools, the circuit is restored.

This is most suitable for devices that often experience excessive heating under extreme usage conditions, such as motor-driven devices, control and monitoring circuits, or in test equipment (where where one must protect against faults in the circuit being tested.) In each case, the device itself does not have an internal fault, but must be kept off until the conditions behind the power surge or high-heat state are removed.