Why do electric heating wires in electric heaters have high resistance

Why do electric heating wires in electric heaters have high resistance

The resistivity of electric heating wires has an appropriate range. If the resistivity is too large or too small, short or long, thin or thick electric heating wires are needed, which poses difficulties in manufacturing and using electric heaters of different powers. An important parameter of electric heating wire is surface power. If the resistivity is too high, the surface power will also increase when a certain current is applied. So for low-power appliances, small diameter small current is chosen, but the size of the current depends on the size of the resistance, and the length and diameter of the heating wire are calculated.

The use of electric heating strips in large industrial electric furnaces requires increasing the surface area to ensure that the surface power does not exceed the standard. At the same time, in order to ensure high power, there must be sufficient current, so that the length, cross-sectional area, and shape of each heating strip are comprehensively considered. So when designing an electric heater, the power of the electric heating wire (strip) used in the electric heater needs to be influenced by various factors.

The allowable surface power of this material, the cross-sectional area of the heating wire (strip), the length of the heating wire, and the shape of the heating wire (straight, spiral, folded, winding, etc.).

Some special electric heaters, such as electric blankets, require a large heat dissipation area and low unit power. If ordinary nickel chromium and iron chromium aluminum electric heating wires are used, extremely thin cross-sectional area electric heating wires are required, which cannot be made at all. So the electric blanket is made of manganese copper wire, which has a much lower electrical resistivity than iron chromium aluminum, in order to have sufficient length.

The resistance of the electric heating wire in an electric heater is selected based on the set power, and the higher the power, the lower the total resistance.

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