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Why does the electric heater wire have a large resistance?

Update:29-11-2019
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The resistance of the electric heater heating wire is s […]

The resistance of the electric heater heating wire is selected according to the set power. The larger the power, the smaller the total resistance.
There is a proper range of the resistivity of the heating wire. If the resistivity is too large or too small, a short or long, thin or thick heating wire is needed. This makes it difficult to manufacture and use electric heaters of large and small power. .
An important parameter of the heating wire is the surface power. The resistivity is too large. After a certain current is passed, the surface power is also large. Therefore, small-power appliances use small diameter and small current, but the size of the current depends on the size of the resistor, and the length and diameter of the heating wire are calculated.
Large industrial electric furnaces use electric heating belts to increase the surface area and ensure that the surface power does not exceed the standard. At the same time, in order to ensure high power, there must be a sufficient current, so that the length and cross-sectional area and shape of each electric heating belt are comprehensively considered.
Therefore, the electric heating wire (belt) used in the electric heater, when designing an electric heater, there are many factors of power.
Power required by this heater
The allowable surface power of this material, the cross-sectional area of ​​the heating wire (belt), the length of the heating wire, the shape of the heating wire (straight, spiral, broken line, winding, etc.), etc.
Some special electric heaters, such as electric blankets, require a large heat dissipation area and low unit power. If you use ordinary nickel-chromium and iron-chromium-aluminum heating wires, you need a positively thin heating wire, which cannot be made at all. . Therefore, the electric blanket is made of manganese copper wire. The resistivity of manganese copper wire is much smaller than iron chromium aluminum, so that it has sufficient length.
In fact, the resistance required by this type of heater and the thickness of the heating wire can be seen at a glance when comparing the size of electric bulbs.

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