Forklift Fuse - A fuse consists of a wire fuse element or a metal
strip of small cross-section compared to the circuit conductors,
and is usually mounted between a pair of electrical terminals.
Normally, the fuse is enclosed by a non-conducting and
non-combustible housing. The fuse is arranged in series capable of
carrying all the current passing throughout the protected circuit.
The resistance of the element produces heat because of the current
flow. The construction and the size of the element is empirically
determined to be certain that the heat produced for a normal
current does not cause the element to attain a high temperature. In
cases where too high of a current flows, the element either melts
directly or it rises to a higher temperature and melts a soldered
joint in the fuse which opens the circuit.
If the metal conductor parts, an electric arc is formed between
un-melted ends of the fuse. The arc starts to grow until the
required voltage to be able to sustain the arc is in fact greater
as opposed to the circuits available voltage. This is what really
leads to the current flow to become terminated. When it comes to
alternating current circuits, the current naturally reverses course
on each and every cycle. This particular process really improves
the speed of fuse interruption. When it comes to current-limiting
fuses, the voltage required to sustain the arc builds up fast
enough to be able to really stop the fault current previous to the
first peak of the AC waveform. This particular effect greatly
limits damage to downstream protected devices.
The fuse is normally made from zinc, copper, alloys, silver or
aluminum in view of the fact that these allow for stable and
predictable characteristics. The fuse ideally, would carry its
current for an indefinite period and melt rapidly on a small
excess. It is essential that the element should not become damaged
by minor harmless surges of current, and should not change or
oxidize its behavior following possible years of service.
So as to increase heating effect, the fuse elements may be shaped.
In big fuses, currents can be separated between multiple metal
strips. A dual-element fuse may have a metal strip which melts
instantly on a short circuit. This kind of fuse could also have a
low-melting solder joint that responds to long-term overload of low
values compared to a short circuit. Fuse elements could be
supported by nichrome or steel wires. This would make sure that no
strain is placed on the element however a spring may be included to
increase the speed of parting the element fragments.
It is normal for the fuse element to be surrounded by materials
that are intended to speed the quenching of the arc. Air,
non-conducting liquids and silica sand are some examples.
Click to Download the pdf