The power of the electric heater is determined by the resistance of the heating wire. The higher the power, the smaller the total resistance.
In a proper range, the electric heating wire has a specific resistance. If the electrical resistivity is too small or too small, a short or very long, very thin or very thick electric heating wire is required, so that the electric heater of the size and power is There are difficulties in manufacturing and use. An important parameter of the heating wire is the surface power. The resistivity is too large, and the surface power is large after a certain current is applied. Therefore, for small power appliances, small diameter and small current are used, but the magnitude of the current is determined by the size of the resistor. The length and diameter of the heating wire are calculated.
When a large industrial electric furnace uses the electric heating belt, the surface area must be increased to ensure that the surface power does not exceed the standard. At the same time, in order to ensure high power, there must be a large enough 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 requires a lot of power factors when designing an electric heater. The allowable surface power of such a 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.).
For example, electric blankets are some special electric heaters. When using electric blankets, the heat dissipation area is required to be large, and the unit power is low. If the usual nickel-chromium and iron-chromium-aluminum electric heating wires are used, the cross-section is required to be thin. The electric heating wire cannot be made at all. Therefore, the electric blanket is made of manganese copper wire, and the resistivity of the manganese copper wire is much smaller than that of the iron chromium aluminum, so that there is sufficient length.