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Fusing Current Equation:
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The fusing current equation calculates the current at which an electrical wire will melt or "fuse" based on its diameter and material properties. This is important for electrical safety and circuit protection design.
The calculator uses the fusing current equation:
Where:
Explanation: The equation shows that fusing current increases with the 1.5 power of wire diameter, and different materials have different fusing characteristics represented by the k constant.
Details: Accurate fusing current calculation is crucial for designing proper circuit protection, preventing electrical fires, and ensuring electrical system safety. It helps determine the appropriate fuse or circuit breaker ratings for different wire sizes.
Tips: Enter the material constant (k) and wire diameter in inches. Common k values: 10244 for copper, 7585 for aluminum, and 1456 for tin. All values must be positive numbers.
Q1: What are typical k values for different materials?
A: Copper typically has k ≈ 10244, aluminum ≈ 7585, and tin ≈ 1456. These values can vary based on specific alloy composition and purity.
Q2: Why is the exponent 3/2 used in the equation?
A: The 3/2 exponent comes from empirical observations that the fusing current increases with the cross-sectional area to the 3/4 power, which relates to the diameter as d^(3/2).
Q3: Is this equation applicable to all wire types?
A: The equation works well for simple round wires but may need modification for stranded wires, different shapes, or special alloys with unusual thermal properties.
Q4: How does insulation affect fusing current?
A: Insulation can significantly affect fusing current by retaining heat. The equation typically assumes bare wire, so derating may be necessary for insulated wires.
Q5: What safety factors should be applied?
A: For safety-critical applications, it's common to use a safety factor of 0.75-0.9 on the calculated fusing current to ensure protection before actual fusing occurs.