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The fuse rating is expressed in terms of
current
voltage
VAR
kVA
current
A fuse is a protective device whose primary function is to break the circuit when the current exceeds a predetermined threshold. Therefore, its rating is specified as the maximum current (in Amperes) that the fuse can carry continuously without melting.
A fuse is a protective device whose primary function is to break the circuit when the current exceeds a predetermined threshold. Therefore, its rating is specified as the maximum current (in Amperes) that the fuse can carry continuously without melting.
H=I2Rt тАФ Heat energy generated in the fuse element
IfuseтАЛтЙИ1.25├ЧIloadтАЛ тАФ Typical sizing guideline for continuous loads
The operation relies on the thermal effect of current, governed by H=I2Rt. When current I exceeds the rated value, the heat generated in the fuse element increases rapidly, causing the element to reach its melting point and interrupt the electrical path, thereby protecting downstream equipment.
Fuses are series devices installed in the phase line.
The 'fusing factor' is defined as the ratio of minimum fusing current to the current rating of the fuse.
A lower fusing factor indicates a more sensitive fuse.
Cost-effective protection
Provides reliable short-circuit protection
Requires manual replacement after operation
Cannot be used as a switch (non-reusable)
Domestic wiring protection
Industrial motor protection
Semiconductor protection (fast-acting fuses)
Voltage rating is also mentioned on a fuse, but it denotes the maximum voltage at which the fuse can safely interrupt the arc.
The current rating is the primary operational parameter.
A is correct тАФ The fuse rating represents the maximum continuous current value the fuse can safely conduct without blowing.
Always remember: A fuse is a series protective device, while a voltmeter is a parallel measuring device; never confuse their ratings!